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Zealut-Dena

Zealut-Dena®

FOR BETTER VISION AND EYE HEALTH SUPPORT

  • 1 Capsule a day provides the required daily norm of zeaxanthin and lutein.
  • Helps protect eyes from negative effects of any device screen and bright light.
  • Supports the vision of people aged 50+, patients with diabetes, cataracts, and age-related macular degeneration (AMD).
  • Consists of 100% natural organic active ingredients.
  • Made in the USA in accordance with GMP standards.

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 WHO NEEDS ZEALUT-DENA?

Anyone who has a low quantity of lutein and zeaxanthin in their daily diet, especially if:

  • You don't eat enough fresh greens and vegetables
  • You are an everyday user of a computer or any mobile device

  • You are exposed to bright light for more than 3-4 hours a day

  • You are aged 50+

  • You have diabetes

  • You have cataracts
  • You have age-related macular degeneration (AMD)

 

WHY ZEALUT-DENA?

  • Zealut-Dena contains scientifically and clinically proven natural ingredients.
  • At birth, the human eye has the necessary levels of lutein and zeaxanthin. However, with time, due to environmental factors and an unbalanced diet, the level of lutein and zeaxanthin in the human body decreases. The human body has a limited ability to synthesize these molecules; therefore, their supply from external sources is helpful.
  • Zealut-Dena contains lutein and zeaxanthin, the only carotenoids that are able to cross the hemato-ophthalmic barrier and protect the eyes.
  • Zealut-Dena supports eye health by helping the body respond to the effects of oxidative stress.
  • 1 Capsule of Zealut-Dena contains 10 mg of lutein. The American Optometric Association recommends intake of at least 7-10 mg/day of lutein, while the average dietary consumption of lutein in the USA is 1.7 mg/day.
  • Zealut-Dena is manufactured in the USA according to GMP standards from carefully selected natural plant sources.

SERVING SIZE: 1 Capsule

SERVINGS PER CONTAINER: 30

Ingredients

Amount Per Serving

% Daily Value

Lutein

10 mg

*

Zeaxanthin

1 mg

*

* Daily Value not established

Other ingredients: microcrystalline cellulose, gelatin, magnesium stearate, silica, dioxide, titanium dioxide, FD&C Yellow No 6, FD&C Green No 3

PROPERTIES OF INGREDIENTS

A healthy antioxidant defense system of the retina is important for protection from photo or light damage (also called photodamage), and the main components of this system are carotenoids. Among more than 1,000 known carotenoids, only lutein and zeaxanthin can penetrate ocular tissue. Because the human body cannot synthesize lutein and zeaxanthin, they must be introduced through diet or supplements. Lutein and zeaxanthin are the main pigments in the macula, which is located in the center of the retina and is responsible for visual acuity. It is a paradox of nature that light is the carrier of visual information, but at the same time it is a risk factor for photoreceptor cells and pigment epithelium. Epidemiological data suggest a correlation between the intensity and spectral composition of light and the development of a number of ocular diseases, in particular the condition known as age-related macular degeneration. Prolonged lutein and zeaxanthin deficiency leads to irreversible deterioration of vision.

RECOMMENDED USE

As an additional source of lutein and zeaxanthin for improvement of visual function in people with the following conditions:

  • myopia
  • symptoms of asthenopia (eye strain)
  • ocular discomfort caused by long hours working at a computer, reading, and other contributors to visual overload
  • disturbances in mesopic vision (vision in low light)
  • congenital retinal dystrophies
  • eye diseases in patients with cardiovascular disease, rheumatoid arthritis, and diabetes

 And for the following purposes:

  • To slow down age-related changes in eye structures such as cataracts, myodesopsia (floaters), and iris atrophy
  • To accelerate healing after eye surgery

DIRECTIONS FOR USE

For adults and children: 1 capsule once or twice a day, immediately following a meal

CONTRAINDICATIONS

Hypersensitivity to one of the components of Zealut-Dena

WARNINGS

  • If pregnant or nursing, consult your healthcare practitioner before taking this product.
  • The color of the product can vary depending on the color changes of natural components.

STORAGE AND PACKAGING

Store in a cool, dry place. Keep out of reach of children.

A bottle contains 30 capsules.

WHAT IS ZEALUT-DENA MADE OF? 

Zealut-Dena contains zeaxanthin and lutein. Healthy nutrition is vital for maintaining eye health. Lutein and zeaxanthin are the two most important eye nutrients that help protect the retina of the eye and reduce the risk of macular degeneration and cataract. Our bodies are unable to produce lutein and zeaxanthin, so we have to receive them from food or through supplements such as Zealut-Dena.

 

WHAT IS LUTEIN AND ZEAXANTHIN? 

Lutein and zeaxanthin belong to xanthophylls (meaning “yellow leaf”) natural pigments from the group of carotenoids, which include 600 natural species. Xanthophylls are mainly found in yellow-orange fruits and dark-green vegetables.

At birth, everyone has the necessary levels of lutein and zeaxanthin. However, exposure to adverse environmental factors, the destructive action of blue light and malnutrition result in a decrease in the levels of lutein and zeaxanthin with age. The human body has a very limited ability to synthesize these molecules; therefore, their supply from external sources is vital.

Lutein and zeaxanthin are the compounds that are largely responsible for the preservation of our vision. They are provided by nature to protect our eyes. Therefore, the intake of these compounds in important for maintaining our eye health. Zealut-Dena provides a balanced source of lutein and zeaxanthin for the human body.

 

HOW MUCH LUTEIN SHOULD I TAKE DAILY? 

According to an estimate by the American Optometric Association, average dietary consumption of lutein and zeaxanthin in the USA is only 1.7 mg/day, whereas the recommended intake is at least 7-10 mg/day of lutein and zeaxanthin.  An easy way to compensate this deficit is to take supplements that contain lutein and zeaxanthin, such as Zealut-Dena. One capsule of  Zealut-Dena contains 10 mg of lutein and 1 mg of zeaxanthin, assuring the daily-recommended quantities of these nutrients.

 

WHAT ARE SOME FOOD SOURCES OF LUTEIN AND ZEAXANTHIN? 

The highest concentrations of lutein and zeaxanthin are found in green vegetables, since plants also use them to protect their photosynthetic apparatus from excessive light. The most lutein and zeaxanthin rich vegetables are spinach, broccoli, kale, green peas and collard greens.

Lutein and zeaxanthin have particularly important qualities: lutein preserves its beneficial properties upon thermal treatment of food products, whereas small amounts of zeaxanthin can be synthesized from lutein directly in the retina when needed.

However, most people do not get enough lutein and zeaxanthin from their diets. According to an estimate by the American Optometric Association, average dietary consumption of lutein and zeaxanthin in the USA is only 1.7 mg/day, whereas the recommended intake is at least 7-10 mg/day. An easy way to compensate for this deficit is to take supplements that contain these compounds, such as Zealut-Dena.

  

WHAT IS COMPUTER VISION SYNDROME (CVS)? HOW CAN ZEALUT-DENA BE BENEFICIAL FOR PEOPLE WITH CVS? 

In many people, prolonged use of electronic screens results in various visual symptoms, such as eyestrain, headaches, ocular discomfort, dry eye, diplopia (double vision), and blurred vision. Taken together, these symptoms are referred to as Computer Vision Syndrome (CVS). Although computer screens do not emit particularly damaging UV light, they do emit blue light, which is also damaging to the retina and might be one of the factors in CVS development. In particular, light emitted by light-emitting diodes (LED), which are used in recent models of computer monitors (as well as energy-saving light bulbs), have been found to be damaging to the retina, presumably because of oxidative stress from reactive oxygen species this light generates. Reactive oxygen species are active radicals that indiscriminately oxidize proteins, lipids and other components of living cells. By focusing light on the retina, the lens further increases retinal damage. Nature has designed an efficient defense mechanism against light damage -- two related compounds from the class of carotenoids: lutein and zeaxanthin. Nevertheless, our bodies are unable to produce lutein and zeaxanthin, and we have to receive them from food. Most people do not get enough lutein and zeaxanthin from their diets. Therefore, supplements such as Zealut-Dena can help compensate for the deficit of lutein and zeaxanthin. Taking at least one capsule of Zealut-Dena daily is expected to be sufficient to alleviate the CVS symptoms, and would be particularly efficient for people with low dietary intake of these carotenoids, i.e. those who do not eat enough green vegetables. It should be also noted that the safety of long-term lutein and zeaxanthin supplementation has been confirmed by clinical studies.

 

IS IT SAFE TO TAKE ZEALUT-DENA IF I HAVE DIABETES? 

People with diabetes are in the risk group of diabetic retinopathy. This eye disease affects >8,000 people in the USA each year and accounts for 12% of new cases of blindness. Oxidative stress is one of the major factors in the development of diabetic retinopathy. It results in an increase in the production of a number of pro-inflammatory molecules in the retina, some of which promote cell death. To protect our eyes from oxidative stress we need to accumulate enough zeaxanthin and lutein in the retina of the eye. Our bodies are unable to produce lutein and zeaxanthin naturally, and we have to receive them from food. Concentration of these carotenoids in the blood depends on their intake. From the blood, they are transported into the eye tissues; their content in the retina follows their intake with food with a delay of 2 weeks.

Concentration of lutein and zeaxanthin in the blood and macula is 2–3 times lower in diabetic retinopathy patients than in healthy people. An independent study reported that taking lutein and zeaxanthin at a proportion similar to that of Zealut-Dena for 3 months significantly improved visual acuity, contrast sensitivity, and macular edema in patients with nonproliferative diabetic retinopathy. Thus, Zealut-Dena can be recommended to patients with this disease.

 

IS IT SAFE TO TAKE ZEALUT-DENA IF I HAVE CATARACT?

Cataract, along with age-related macular degeneration, is a major cause of blindness in elderly people. Cataract is an opacity of the lens that develops gradually over many years and eventually prevents light from reaching the retina.   Oxidative stress, particularly that caused by UV light, plays an important role in cataract development by promoting oxidation of lens proteins. An efficient natural defense mechanism against light- and oxidative stress–induced damage in the eye is provided by two related compounds: lutein and zeaxanthin.

Three large-scale studies conducted in the USA in the last quarter of the 20th century concluded that lutein and zeaxanthin are the only carotenoids associated with the reduced risk of nuclear cataract development: their intake reduced the risk by as much as half. Most people do not get enough lutein and zeaxanthin from their diets, which is why supplements such as Zealut-Dena help compensate the deficit of those compounds and protect our eyes. The intake of lutein and zeaxanthin (6–7 mg/day, i.e. less than the content of 1 Zealut-Dena capsule) was found to significantly reduce the number of required cataract surgeries. 

 

WHAT IS AGE-RELATED MACULAR DEGENERATION (AMD)? HOW CAN ZEALUT-DENA BE BENEFICIAL FOR PEOPLE WITH AMD? 

Age-related macular degeneration (AMD) is the most common cause of blindness, especially in the elderly. AMD affects the macula, the central area of the retina that provides high-acuity vision. The macula contains a high density of light-sensitive (photoreceptor) cells. The photoreceptor cells of the macula have relatively low sensitivity and need bright light to function. Yet, the flip side is that the macula is most vulnerable to the harmful effects of light, which causes the formation of so-called reactive oxygen species, active radicals that indiscriminately oxidize proteins, lipids and other components of living cells. In patients with AMD, light is particularly damaging because it synergistically accelerates the death of photoreceptor cells.  Fortunately, nature has designed an efficient defense mechanism against light damage.

Carotenoids lutein and zeaxanthin protect the retina against light damage. They filter out the most damaging short-wavelength irradiation (blue light and UV) and neutralize the reactive oxygen species. Nevertheless, our bodies are unable to produce lutein and zeaxanthin, so we have to receive them from food or through supplements such as Zealut-Dena.

Some scientists reported that in AMD patients, longer supplementation (for up to a year) improves contrast sensitivity and visual acuity.

 

HOW SOON SHOULD I EXPECT THE RESULT OF TAKING ZEALUT-DENA? 

The effect of daily supplementation with lutein and zeaxanthin for 8 weeks has been found to significantly increase the content of macular pigment as soon as after 2 weeks of daily intake.  

 

HOW LONG CAN I TAKE ZEALUT-DENA? 

The absence of side effects and safety of long-term intake of lutein and zeaxanthin supplements have been confirmed by clinical studies. Zealut-Dena contains only zeaxanthin and lutein as active ingredients. Therefore, there are no time restrictions on regular intake of Zealut-Dena if consumed at approved daily dosage (1-2 capsules a day).

 

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BENEFITS OF LUTEIN AND ZEAXANTHIN SUPPLEMENTATION IN PATIENTS WITH DIABETIC RETINOPATHY

Retinopathies are characterized by inflammation and vascular remodeling and may be caused by systemic disorders. One such disorder is diabetes, which may result in the development of diabetic retinopathy, which affects >8,000 individuals in the USA each year and accounts for 12% of new cases of blindness [1].

[endshort]

BENEFITS OF LUTEIN AND ZEAXANTHIN SUPPLEMENTATION IN PATIENTS WITH DIABETIC RETINOPATHY

Retinopathies are characterized by inflammation and vascular remodeling and may be caused by systemic disorders. One such disorder is diabetes, which may result in the development of diabetic retinopathy, which affects >8,000 individuals in the USA each year and accounts for 12% of new cases of blindness [1].

 

 Although multiple carotenoid species are present in blood plasma, only lutein and zeaxanthin are able to cross the hemato-ophthalmic barrier and accumulate in the eye tissues, including the retina, where their concentration is four orders of magnitude higher than in the blood [2,3,4]. Within the retina, lutein and zeaxanthin are concentrated in the macula, where they form macular pigment. As much as 25% of their total retinal content is found in the outer segments of the rod photoreceptor neurons [5], where the light receptor rhodopsin and enzymes of its downstream signaling cascade are located.

 

Macular pigment (i.e., lutein and zeaxanthin) is thought to play a dual protective role by filtering out the most damaging short-wavelength irradiation (blue light and UV) and by scavenging reactive oxygen species [6, 7].  Thus, a reduction in macular pigment content would increase oxidative stress in the retina. Oxidative stress is one of the major factors in the pathogenesis of diabetic retinopathy [8]. In particular, it results in an increase in the production or activation of pro-inflammatory molecules, such as nuclear transcriptional factor-κB (NF-κB), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) [9, 10]. Activation of NF-kB promotes cell death (apoptosis) in the retina [11], which may be a major factor in the development of this disease [12].

 

The content of macular pigment depends on the dietary intake of lutein and zeaxanthin and follows changes in the uptake of these carotenoids with a delay of two to three weeks [13]. Thus, an increased intake of lutein and zeaxanthin could be expected to be beneficial for patients with diabetic retinopathy.

 

A relationship between plasma concentrations of various carotenoids and diabetic retinopathy was investigated in 111 individuals with type 2 diabetes using analysis of blood and urine and a lifestyle questionnaire [14]. This study found that the concentration of lutein, zeaxanthin, and lycopene combined, but not the concentration of α-carotene, β-carotene, and β-cryptoxanthin combined, was significantly lower in the subjects with retinopathy than in the non-retinopathy group. A higher ratio of the former group of carotenoids to the latter group was also associated with a lower risk of diabetic retinopathy, whereas a higher concentration of the latter groups was associated with a greater risk of the disease [14]. Whereas Brazionis and coworkers [14] measured concentrations of lutein and zeaxanthin together with that of lycopene, which might potentially be a confounding factor, a later study [15] reported that serum levels of both lutein and zeaxanthin (measured separately) in healthy subjects were approximately three times those in patients with nonproliferative diabetic retinopathy. An earlier study assessed the association between serum levels of two other antioxidants, ascorbic acid (vitamin C) and α-tocopherol (vitamin E), with the development of diabetic retinopathy, and found no evidence of such association [16]. Taken together, the results of these studies indicate a specific association of lutein and zeaxanthin, but not of several other antioxidants, with diabetic retinopathy.

 

In line with the well-documented dependence of the content of macular pigment on the plasma levels of lutein and zeaxanthin [13], two studies reported a dramatic reduction (approximately 2–2.5 fold) in the macular pigment content (measured as optical density) in patients with diabetic retinopathy in comparison with healthy subjects [17, 18].

 

However, correlation between the plasma levels of lutein and zeaxanthin or macular pigment content and the risk of diabetic retinopathy suggests but does not prove the causal link between these carotenoids and the disease, and by itself is insufficient to determine whether lutein and zeaxanthin supplements may delay the onset or progression of diabetic retinopathy. Yet, some studies have also reported direct beneficial effects of lutein and zeaxanthin supplementation in patients with diabetic retinopathy.

 

A study that involved 30 relatively young (20–30 years of age) type 1 diabetes patients examined the effect of supplementation with lutein in combination with docosahexaenoic acid (an omega-3 polyunsaturated fatty acid) for three months; the participants were subjected to a computerized perimetry test at three and six months after the onset of treatment [19]. The authors reported a significant increase in mean sensitivity and a significant decrease in short-term fluctuation in patients who received the supplement in comparison with the placebo group; the relative contributions of lutein and docosahexaenoic acid have not been assessed.

 

Hu and coworkers [15] found that supplementation with lutein (6 mg/day) and zeaxanthin (0.5 mg/day) for three months significantly improved visual acuity, contrast sensitivity and macular edema in patients with nonproliferative diabetic retinopathy. These data provide direct evidence that lutein and zeaxanthin supplementation at a proportion similar to that used in Zealut-Dena (12:1 vs. 10:1, respectively) and at a dosage lower than that in one Zealut-Dena capsule alleviates at least some symptoms of diabetic retinopathy.

 

Overall, although the details of the role lutein and zeaxanthin in protection of patients with diabetes against diabetic retinopathy remain to be investigated, the data available to date indicate that [1] both the plasma levels of these carotenoids and macular pigment content are reduced in individuals with diabetic retinopathy; and [2] lutein and zeaxanthin supplementation for several months, which is known to increase the content of macular pigment, alleviates the symptoms. This provides a clear rationale for recommending lutein and zeaxanthin supplementation in patients with diabetic retinopathy.

 

References

  1. Aiello, L.P. Implications for novel growth factor therapies in diabetic retinopathy. Curr Op Endocrinol Diabetes Obesity 3, 307-314 (1996).
  2. Stringham, J.M. & Hammond, B.R., Jr. Dietary lutein and zeaxanthin: possible effects on visual function. Nutr Rev 63, 59-64 (2005).
  3. Whitehead, A.J., Mares, J.A. & Danis, R.P. Macular pigment: a review of current knowledge. Arch Ophthalmol 124, 1038-1045 (2006).
  4. Widomska, J. & Subczynski, W.K. Why has Nature Chosen Lutein and Zeaxanthin to Protect the Retina? J Clin Exp Ophthalmol 5, 326 (2014).
  5. Sommerburg, O.G. et al. Lutein and zeaxanthin are associated with photoreceptors in the human retina. Curr Eye Res 19, 491-495 (1999).
  6. Krinsky, N.I., Landrum, J.T. & Bone, R.A. Biologic mechanisms of the protective role of lutein and zeaxanthin in the eye. Annu Rev Nutr 23, 171-201 (2003).
  7. Loane, E., Kelliher, C., Beatty, S. & Nolan, J.M. The rationale and evidence base for a protective role of macular pigment in age-related maculopathy. Br J Ophthalmol 92, 1163-1168 (2008).
  8. Madsen-Bouterse, S.A. & Kowluru, R.A. Oxidative stress and diabetic retinopathy: pathophysiological mechanisms and treatment perspectives. Rev Endocr Metab Disord 9, 315-327 (2008).
  9. Chan, P.S., Kanwar, M. & Kowluru, R.A. Resistance of retinal inflammatory mediators to suppress after reinstitution of good glycemic control: novel mechanism for metabolic memory. J Diabetes Complications 24, 55-63 (2010).
  10. Joussen, A.M. et al. A central role for inflammation in the pathogenesis of diabetic retinopathy. FASEB J 18, 1450-1452 (2004).
  11. Romeo, G., Liu, W.H., Asnaghi, V., Kern, T.S. & Lorenzi, M. Activation of nuclear factor-kappaB induced by diabetes and high glucose regulates a proapoptotic program in retinal pericytes. Diabetes 51, 2241-2248 (2002).
  12. Barber, A.J., Gardner, T.W. & Abcouwer, S.F. The significance of vascular and neural apoptosis to the pathology of diabetic retinopathy. Invest Ophthalmol Vis Sci 52, 1156-1163 (2011).
  13. Loughman, J., Nolan, J.M. & Beatty, S. Impact of dietary carotenoid deprivation on macular pigment and serum concentrations of lutein and zeaxanthin. Br J Nutr 108, 2102-2103 (2012).
  14. Brazionis, L., Rowley, K., Itsiopoulos, C. & O'Dea, K. Plasma carotenoids and diabetic retinopathy. Br J Nutr 101, 270-277 (2009).
  15. Hu, B.J., Hu, Y.N., Lin, S., Ma, W.J. & Li, X.R. Application of Lutein and Zeaxanthin in nonproliferative diabetic retinopathy. Int J Ophthalmol 4, 303-306 (2011).
  16. Millen, A.E. et al. Relations of serum ascorbic acid and alpha-tocopherol to diabetic retinopathy in the Third National Health and Nutrition Examination Survey. Am J Epidemiol 158, 225-233 (2003).
  17. Davies, N.P. & Morland, A.B. Color matching in diabetes: optical density of the crystalline lens and macular pigments. Invest Ophthalmol Vis Sci 43, 281-289 (2002).
  18. Lima, V.C. et al. Macular pigment optical density measured by dual-wavelength autofluorescence imaging in diabetic and nondiabetic patients: a comparative study. Invest Ophthalmol Vis Sci 51, 5840-5845 (2010).
  19. Domanico, D. et al. Retinal Effects of Lutein and DHA on Diabetic Retinopathy. Invest Ophthalmol Vis Sci 47, E-Abstract 975 (2006).

[endmore]

[more]

 

BENEFITS OF LUTEIN AND ZEAXANTHIN INTAKE IN PATIENTS WITH AGE-RELATED MACULAR DEGENERATION, RETINITIS PIGMENTOSA AND CATARACTS

Oxidative stress is well known to contribute to the onset and progression of a number of eye diseases, including at least some forms of retinal degeneration, particularly age-related macular degeneration (AMD) [1], which is the most common cause of blindness in developed countries.

[endshort]

BENEFITS OF LUTEIN AND ZEAXANTHIN INTAKE IN PATIENTS WITH AGE-RELATED MACULAR DEGENERATION, RETINITIS PIGMENTOSA AND CATARACTS

Oxidative stress is well known to contribute to the onset and progression of a number of eye diseases, including at least some forms of retinal degeneration, particularly age-related macular degeneration (AMD) [1], which is the most common cause of blindness in developed countries.

 

Oxidative stress, especially that caused by UV light, also plays an important role in cataract development promoting oxidation of lens proteins [2,  3]. Therefore, a number of studies have assessed the effects of supplementation with several antioxidant nutrients, including lutein and zeaxanthin, on the risks of onset and progression of these diseases.

 

Although multiple carotenoid species are present in blood plasma, only lutein and zeaxanthin are able to cross the hemato-ophthalmic barrier and accumulate in the eye tissues, including the retina, where their concentration is 4 orders of magnitude higher than in the blood [2, 4].  These carotenoids are thought to protect the retina in a dual way: by filtering out the most damaging short-wavelength irradiation (blue light and UV) and by scavenging reactive oxygen species.

 

Within the retina, lutein and zeaxanthin are concentrated in the macula, with as much as 25% of their total retinal content found in the outer segments of the rod photoreceptor neurons [5], where the light receptor rhodopsin and enzymes of its downstream signaling cascade are located. Since rods are much more sensitive to light and therefore to photodamage than cone photoreceptors, accumulation of carotenoids in rod outer segments suggests a direct function of lutein and zeaxanthin in rod protection from photodamage.

 

Age-related macular degeneration

The effects of taking lutein and zeaxanthin supplementation on the content and spatial distribution of the macular pigment have been extensively studied. Although the results of studies conducted during the first years of this century appeared  to be inconclusive [6], most studies of the last decade have reported at least some benefits of lutein and zeaxanthin supplementation. Examples of such studies are summarized below.

Taking a daily supplement of lutein, zeaxanthin and meso-zeaxanthin (a carotenoid that is formed from lutein directly in the retina and is a component of macular pigment along with lutein and zeaxanthin [7]) for eight weeks has been found to significantly increase the content of macular pigment (measured as optical density), as soon as after two weeks of supplementation, both in healthy people and those with AMD [8]. The authors also found that the spatial profile of macular pigment was atypical in some subjects, mainly those with AMD, and that supplementation restored the normal profile.

 

A more recent study investigated the effects of lutein and zeaxanthin on macular pigment and visual function in patients with early AMD [9]. Daily intake of either 20 mg lutein alone or 10 mg lutein and 10 mg zeaxanthin was found to significantly increase the macular pigment content in comparison with the placebo group; the authors also reported a significant improvement in contrast sensitivity and a trend toward improvement in best-corrected visual acuity after 48 weeks of carotenoid supplementation. Furthermore, they found a significant correlation between these two parameters of visual function and the macular pigment content, suggesting that the increase in the latter underlies the improvement of visual function.

 

Similar results for the macular pigment content and contrast sensitivity have been reported by an independent study [10]. Intriguingly, differential effects of lutein and zeaxanthin in patients with mild-to-moderate AMD have been reported: supplementation with either of the two carotenoids increased the macular pigment content, but lutein was more beneficial for rod-based monochromatic high-sensitivity vision, whereas zeaxanthin was more beneficial for cone-based color vision [11]. Another important finding of the latter study was that equally dosed (i.e., atypical dietary ratio) lutein and zeaxanthin performed worse than each carotenoid individually, which emphasizes the importance of an optimal ratio between the two carotenoids (as implemented in Zealut-Dena).

 

Whereas the above studies provided evidence for the efficacy of lutein and zeaxanthin in restoring the content and spatial profile of macular pigment and improving at least some parameters of visual function in AMD patients, they have not addressed a separate question of whether lutein and zeaxanthin supplements may affect AMD onset or progression.

 

AREDS2, a large multicenter study conducted in 2006–2012, revealed that the protective effect of lutein and zeaxanthin supplementation was significant only in subjects whose dietary intake of these carotenoids was within the lowest quintile [12, 13] (which might in part explain inconclusive results of earlier studies). Moreover, lutein and zeaxanthin delayed progression of advanced AMD (categories 3–4), albeit only by 10% [12]. Lutein (10 mg/day) and zeaxanthin (2 mg/day) have also been recommended as a replacement of β-carotene in the AREDS formulation (vitamins C and E, β-carotene, and zinc) because of the association of β-carotene with an increased incidence of lung cancer in former smokers [14]. Taken together, the results of the AREDS2 study and available smaller studies suggest that lutein and zeaxanthin at the above doses (i.e., similar to their content in one to two Zealut-Dena capsules), would be beneficial for category 3 and 4 (i.e., advanced AMD) patients [12]; potential long-term side effects (>5 years) of lutein and zeaxanthin supplementation have not yet been investigated.

 

Overall, although the benefits of taking lutein and zeaxanthin for different groups of AMD patients need further investigation, this supplement can be recommended at least as an appropriate cautionary measure [15], especially for patients with low dietary intake of these carotenoids [12, 13].

 

Other forms of retinal degeneration

Whereas the effects of lutein and zeaxanthin are best studied in AMD patients, some studies have assessed whether supplementation with these carotenoids would benefit patients with other forms of retinal degeneration.

 

Consistent with the results of the AMD studies, taking lutein (20 mg/day) for six months significantly increased the content of macular pigment in patients with retinitis pigmentosa and Usher syndrome (a combination of retinitis pigmentosa and a sensorineural hearing loss) [16], choroideremia (a congenital X-linked retinal degeneration) [17], CRB1–associated retinal degeneration [18, 19], and ABCA4-associated retinal degeneration [19], but did not result in an improvement in central vision during the study periods, suggesting that either lutein has no benefit for patients with these diseases, or its effect takes longer than six months to develop.

 

A small-scale study on 13 retinitis pigmentosa patients [20] reported beneficial effects of taking a higher dose of lutein (40 mg/day for 9 weeks, followed by 20 mg/day for 15 weeks). The authors found improvements in visual acuity and mean visual-field area, which were detectable as early as two to four weeks after the beginning of treatment and plateaued at 6–14 weeks. Curiously, blue-eyed participants benefited more from lutein intake than dark-eyed participants. The apparent discrepancies between the results of different studies is perhaps not surprising, because retinitis pigmentosa is a very heterogeneous group of diseases caused by mutations in several dozens of different genes, and in many cases the underlying genetic cause of retinal degeneration remains unknown. A tentative conclusion that can be made at present is that high doses and long treatment periods may be more beneficial for retinitis pigmentosa patients.

 

Cataract

The five-year Beaver Dam Eye Study, which enrolled 1,354 subjects and was conducted between 1988 and 1995, found that lutein and zeaxanthin were the only carotenoids associated with the reduced risk of nuclear cataract development: their intake in the highest quintile reportedly reduced the risk by as much as half [21]. These results were corroborated by two larger-scale studies conducted in the last quarter of the 20th century. The Nurses’ Health Study, which was conducted in the USA and Japan and enrolled female registered nurses, found that increased intake of lutein (≥6  mg/day) and zeaxanthin reduced the number of required cataract surgeries [22]. Similar results were reported by the parallel Health Professionals Follow-Up Study, which enrolled male health professionals: this study found a decrease in the need for cataract surgeries as a result of increased intake of lutein and zeaxanthin (6.9 mg/day) [23]. However, some other studies at that time failed to find a significant association between the cataract risk and carotenoid supplementation, and a Food and Drug Administration review conducted in 2006 concluded that there was no reliable evidence for the ability of lutein and zeaxanthin to reduce the risk of cataracts [6]. Nevertheless, a number of later studies have confirmed the beneficial effects of these carotenoids, and a recent meta-analysis of 13 observational studies (18,999 participants in total) concluded that the blood levels of both lutein and zeaxanthin (the two carotenoid species were analyzed separately), but not those of three other carotenoids (β-carotene, lycopene, and β-cryptoxanthin), are inversely associated with risk of age-related cataract [24].  

 

References

  1. Khandhadia, S. & Lotery, A. Oxidation and age-related macular degeneration: insights from molecular biology. Expert Rev Mol Med12, e34 (2010).
  2. Stringham, J.M. & Hammond, B.R., Jr. Dietary lutein and zeaxanthin: possible effects on visual function. Nutr Rev 63, 59-64 (2005).
  3. Sliney, D.H. UV radiation ocular exposure dosimetry. J Photochem Photobiol B 31, 69-77 (1995).
  4. Whitehead, A.J., Mares, J.A. & Danis, R.P. Macular pigment: a review of current knowledge. Arch Ophthalmol 124, 1038-1045 (2006).
  5. Sommerburg, O.G. et al. Lutein and zeaxanthin are associated with photoreceptors in the human retina. Curr Eye Res 19, 491-495 (1999).
  6. Trumbo, P.R. & Ellwood, K.C. Lutein and zeaxanthin intakes and risk of age-related macular degeneration and cataracts: an evaluation using the Food and Drug Administration's evidence-based review system for health claims. Am J Clin Nutr 84, 971-974 (2006).
  7. Widomska, J. & Subczynski, W.K. Why has Nature Chosen Lutein and Zeaxanthin to Protect the Retina? J Clin Exp Ophthalmol 5, 326 (2014).
  8. Connolly, E.E. et al. Augmentation of macular pigment following supplementation with all three macular carotenoids: an exploratory study. Curr Eye Res 35, 335-351 (2010).
  9. Ma, L. et al. Effect of lutein and zeaxanthin on macular pigment and visual function in patients with early age-related macular degeneration. Ophthalmology 119, 2290-2297 (2012).
  10. Sabour-Pickett, S. et al. Supplementation with Three Different Macular Carotenoid Formulations in Patients with Early Age-Related Macular Degeneration. Retina (2014).
  11. Richer, S.P. et al. Randomized, double-blind, placebo-controlled study of zeaxanthin and visual function in patients with atrophic age-related macular degeneration: the Zeaxanthin and Visual Function Study (ZVF) FDA IND #78, 973. Optometry 82, 667-680 e666 (2011).
  12. Andreatta, W. & El-Sherbiny, S. Evidence-based nutritional advice for patients affected by age-related macular degeneration. Ophthalmologica 231, 185-190 (2014).
  13. Pinazo-Duran, M.D. et al. Oxidative stress and its downstream signaling in aging eyes. Clin Interv Aging 9, 637-652 (2014).
  14. Group, T.A.-R.E.D.S.A.R. Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration: the Age-Related Eye Disease Study 2 (AREDS2) randomized clinical trial. JAMA 309, 2005-2015 (2013).
  15. Zhao, L. & Sweet, B.V. Lutein and zeaxanthin for macular degeneration. Am J Health Syst Pharm 65, 1232-1238 (2008).
  16. Aleman, T.S. et al. Macular pigment and lutein supplementation in retinitis pigmentosa and Usher syndrome. Invest Ophthalmol Vis Sci 42, 1873-1881 (2001).
  17. Duncan, J.L. et al. Macular pigment and lutein supplementation in choroideremia. Exp Eye Res 74, 371-381 (2002).
  18. Aleman, T.S. et al. CRB1– Associated Retinal Degeneration: Macular Pigment and Lutein Supplementation. Invest Ophtalmol Vis Sci46, Abstract 556 (2005).
  19. Aleman, T.S. et al. Macular pigment and lutein supplementation in ABCA4-associated retinal degenerations. Invest Ophthalmol Vis Sci 48, 1319-1329 (2007).
  20. Dagnelie, G., Zorge, I.S. & McDonald, T.M. Lutein improves visual function in some patients with retinal degeneration: a pilot study via the Internet. Optometry 71, 147-164 (2000).
  21. Lyle, B.J., Mares-Perlman, J.A., Klein, B.E., Klein, R. & Greger, J.L. Antioxidant intake and risk of incident age-related nuclear cataracts in the Beaver Dam Eye Study. Am J Epidemiol 149, 801-809 (1999).
  22. Chasan-Taber, L. et al. A prospective study of carotenoid and vitamin A intakes and risk of cataract extraction in US women. Am J Clin Nutr 70, 509-516 (1999).
  23. Brown, L. et al. A prospective study of carotenoid intake and risk of cataract extraction in US men. Am J Clin Nutr 70, 517-524 (1999).
  24. Cui, Y.H., Jing, C.X. & Pan, H.W. Association of blood antioxidants and vitamins with risk of age-related cataract: a meta-analysis of observational studies. Am J Clin Nutr 98, 778-786 (2013).

[endmore]

[more]

BENEFITS OF TAKING ZEALUT-DENA (LUTEIN AND ZEAXANTHIN) FOR PATIENTS WITH RETINITIS PIGMENTOSA

Retinitis pigmentosa is a heterogenous group of hereditary conditions that lead to gradual retinal degeneration that results from progressive loss of rod and cone photoreceptor cells and results in the loss of night vision (provided by rod photoreceptor neurons) in adolescents, followed by the loss of side vision in young adults (which causes so-called "tunnel vision"), and finally by the loss of central vision (high-acuity daylight vision, provided by cone photoreceptors) [1, 2]. Despite similar disease progression, the etiology of retinitis pigmentosa is different in different patients, with causative mutations identified in >45 genes [1]. However, in many patients, the exact causes of the disease remain unknown.

[endshort]

BENEFITS OF TAKING ZEALUT-DENA (LUTEIN AND ZEAXANTHIN) FOR PATIENTS WITH RETINITIS PIGMENTOSA

Retinitis pigmentosa is a heterogenous group of hereditary conditions that lead to gradual retinal degeneration that results from progressive loss of rod and cone photoreceptor cells and results in the loss of night vision (provided by rod photoreceptor neurons) in adolescents, followed by the loss of side vision in young adults (which causes so-called "tunnel vision"), and finally by the loss of central vision (high-acuity daylight vision, provided by cone photoreceptors) [1, 2]. Despite similar disease progression, the etiology of retinitis pigmentosa is different in different patients, with causative mutations identified in >45 genes [1]. However, in many patients, the exact causes of the disease remain unknown.

 

Oxidative stress is well known to contribute to the onset and progression of a number of eye diseases. In retinitis pigmentosa, oxidative stress primarily contributes to the loss of central vision, likely because cones become vulnerable after the death of rods, which constitute approximately 90% of all photoreceptor neurons and neutralize most reactive oxygen species; in addition, cones have higher content of mitochondria, which produce most reactive oxygen species during respiration [2].

 

Although multiple carotenoid species are present in blood plasma, only lutein and zeaxanthin are able to cross the hemato-ophthalmic barrier and accumulate in the eye tissues, including the retina, where their concentration is four orders of magnitude higher than in the blood [3, 4]. These carotenoids are thought to protect the retina in a dual way: by filtering out the most damaging short-wavelength irradiation (blue light and UV) and by scavenging reactive oxygen species [5, 6].

 

Within the retina, lutein and zeaxanthin are concentrated in the macula and form so-called macular pigment. As much as 25% of total retinal content of these carotenoids is found in the outer segments of the rod photoreceptor neurons [7] (which are lost first in the course of retinitis pigmentosa progression [1, 2]), where the light receptor rhodopsin and enzymes of its downstream signaling cascade are located. Since rods are much more sensitive to light and therefore to photodamage than cone photoreceptors, accumulation of carotenoids in rod outer segments suggests a direct function of lutein and zeaxanthin in rod protection from photodamage.

 

The content of macular pigment depends on the dietary intake of lutein and zeaxanthin and follows changes in the uptake of these carotenoids with a delay of two to three weeks [8]. In retinitis pigmentosa patients, macular pigment was found to increase with increasing serum concentration of lutein but not zeaxanthin [9]. Thus, supplementation with at least lutein could be expected to be beneficial for retinitis pigmentosa patients (it should be noted that lutein is the main component of Zealut-Dena).

 

Consistent with these data, taking lutein (20 mg/day) for six months significantly increased the content of macular pigment in patients with retinitis pigmentosa and Usher syndrome (a combination of retinitis pigmentosa and a sensorineural hearing loss) [10], choroideremia (a congenital X-linked retinal degeneration) [11], CRB1–associated retinal degeneration [12, 13], and ABCA4-associated retinal degeneration [13], although it was not accompanied by a statistically significant improvement in central vision during the study periods, suggesting that either lutein has no benefit for patients with these diseases, or its effect takes longer than six months to develop.

 

A number of studies have assessed the effects of supplementation with lutein the progressive decline in visual function in retinitis pigmentosa patients. A small-scale study on 13 retinitis pigmentosa patients [14] reported beneficial effects of taking a higher dose of lutein (40 mg/day for nine weeks, followed by 20 mg/day for 15 weeks). The authors found improvements in visual acuity and mean visual-field area, which were detectable as early as two to four weeks after the beginning of treatment and plateaued at 6–14 weeks. Curiously, blue-eyed participants benefited more from lutein intake than dark-eyed participants.

 

Berson and coworkers [15] investigated the effects of lutein (12 mg daily, i.e. similar to the content in one capsule of Zealut-Dena) on the decline in visual function in retinitis pigmentosa patients who received vitamin A. Lutein was found to slow the loss of the mid-peripheral visual field; the patients with the highest macular pigment content showed the slowest decline in field sensitivity, supporting the causal link between lutein and visual function. The strong points of this study were that it enrolled a considerable number of patients (225) and the observation period was as long as four years, with no signs of lutein toxicity noted over this period.

 

A study conducted at Johns Hopkins University using a cohort consisting of 44 retinitis pigmentosa patients and 11 patients with related retinal degenerations [16] reported no significant effects of lutein (10 mg/day for 12 weeks and 30 mg/day for the following 12 weeks) but found a trend towards improvement in visual acuity and contrast sensitivity, although none of these effects reached statistical significance. Potentially important could be the observation that 11 out of 13 subjects who decided to withdraw from the study were receiving placebo; this might indicate that lutein supplementation had positive effects that were not quantified in the study but were perceived by the participants.

 

A later study at the same university [17] assessed the effect of lutein on visual acuity and contrast sensitivity. The choice of the subjects (36) was restricted to retinitis pigmentosa; the same lutein supplementation scheme was used. In this study, lutein significantly improved central visual field with an estimated six-week delay. As in the first study, there was also a tendency towards improvement in visual acuity, although it did not reach statistical significance. Safety of lutein supplementation was also noted.

 

A decline in visual acuity in retinitis pigmentosa patients is due not only to the loss of photoreceptor cells, but also to retinal thickening, which is thought to be due to edema [18]. Lutein alone administered for 48 weeks was reported to have no significant effect on retinal thickness in retinitis pigmentosa patients regardless of the presence or absence of cystoid macular edema [19]. However, Hu and coworkers [20] found that supplementation with lutein (6 mg/day) and zeaxanthin (0.5 mg/day) for three months significantly improved visual acuity, contrast sensitivity, and macular edema in patients with nonproliferative diabetic retinopathy. Taking into account heterogeneity of retinitis pigmentosa, it seems reasonable to assume that supplementation with these carotenoids might have a similar effect in some cases of retinitis pigmentosa as well.

 

Some discrepancies between the results of different studies is perhaps not surprising, because retinitis pigmentosa is a very heterogenous group of diseases caused by mutations in several dozens of different genes, and in many cases the underlying genetic cause of retinal degeneration remains unknown. Overall, although the details of the role lutein and zeaxanthin in slowing down the decline in visual function in patients with this disease remain to be investigated, the data available to date indicate that high doses of lutein and/or long treatment periods may be most beneficial for retinitis pigmentosa patients.

 

References

  1. Hartong, D.T., Berson, E.L. & Dryja, T.P. Retinitis pigmentosa. Lancet 368, 1795-1809 (2006).
  2. Punzo, C., Xiong, W. & Cepko, C.L. Loss of daylight vision in retinal degeneration: are oxidative stress and metabolic dysregulation to blame? J Biol Chem 287, 1642-1648 (2012).
  3. Stringham, J.M. & Hammond, B.R., Jr. Dietary lutein and zeaxanthin: possible effects on visual function. Nutr Rev 63, 59-64 (2005).
  4. Whitehead, A.J., Mares, J.A. & Danis, R.P. Macular pigment: a review of current knowledge. Arch Ophthalmol 124, 1038-1045 (2006).
  5. Krinsky, N.I., Landrum, J.T. & Bone, R.A. Biologic mechanisms of the protective role of lutein and zeaxanthin in the eye. Annu Rev Nutr 23, 171-201 (2003).
  6. Loane, E., Kelliher, C., Beatty, S. & Nolan, J.M. The rationale and evidence base for a protective role of macular pigment in age-related maculopathy. Br J Ophthalmol 92, 1163-1168 (2008).
  7. Sommerburg, O.G. et al. Lutein and zeaxanthin are associated with photoreceptors in the human retina. Curr Eye Res 19, 491-495 (1999).
  8. Loughman, J., Nolan, J.M. & Beatty, S. Impact of dietary carotenoid deprivation on macular pigment and serum concentrations of lutein and zeaxanthin. Br J Nutr 108, 2102-2103 (2012).
  9. Sandberg, M.A., Johnson, E.J. & Berson, E.L. The relationship of macular pigment optical density to serum lutein in retinitis pigmentosa. Invest Ophthalmol Vis Sci 51, 1086-1091 (2010).
  10. Aleman, T.S. et al. Macular pigment and lutein supplementation in retinitis pigmentosa and Usher syndrome. Invest Ophthalmol Vis Sci 42, 1873-1881 (2001).
  11. Duncan, J.L. et al. Macular pigment and lutein supplementation in choroideremia. Exp Eye Res 74, 371-381 (2002).
  12. Aleman, T.S. et al. CRB1– Associated Retinal Degeneration: Macular Pigment and Lutein Supplementation. Invest Ophtalmol Vis Sci46, Abstract 556 (2005).
  13. Aleman, T.S. et al. Macular pigment and lutein supplementation in ABCA4-associated retinal degenerations. Invest Ophthalmol Vis Sci 48, 1319-1329 (2007).
  14. Dagnelie, G., Zorge, I.S. & McDonald, T.M. Lutein improves visual function in some patients with retinal degeneration: a pilot study via the Internet. Optometry 71, 147-164 (2000).
  15. Berson, E.L. et al. Clinical trial of lutein in patients with retinitis pigmentosa receiving vitamin A. Arch Ophthalmol 128, 403-411 (2010).
  16. Dagnelie, G., Melia, M. & Sunness, J.S. Lutein Supplementation in RP: Vision Measures in the Clinic. Invest Ophthalmol Vis Sci 44, E-Abstract 780 (2003).
  17. Bahrami, H., Melia, M. & Dagnelie, G. Lutein supplementation in retinitis pigmentosa: PC-based vision assessment in a randomized double-masked placebo-controlled clinical trial [NCT00029289]. BMC Ophthalmol 6, 23 (2006).
  18. Sandberg, M.A., Brockhurst, R.J., Gaudio, A.R. & Berson, E.L. The association between visual acuity and central retinal thickness in retinitis pigmentosa. Invest Ophthalmol Vis Sci 46, 3349-3354 (2005).
  19. Adackapara, C.A., Sunness, J.S., Dibernardo, C.W., Melia, B.M. & Dagnelie, G. Prevalence of cystoid macular edema and stability in oct retinal thickness in eyes with retinitis pigmentosa during a 48-week lutein trial. Retina 28, 103-110 (2008).
  20. Hu, B.J., Hu, Y.N., Lin, S., Ma, W.J. & Li, X.R. Application of Lutein and Zeaxanthin in nonproliferative diabetic retinopathy. Int J Ophthalmol 4, 303-306 (2011).

[endmore]

[more]

 

BENEFITS OF ZEALUT-DENA (LUTEIN AND ZEAXANTHIN) IN SUBJECTS WITH COMPUTER VISION SYNDROME

According to a survey conducted more than a decade ago, more than half of the working population used computers at that time [1], and the proportion of people using various electronic screens for work and in everyday life is thought to be now close to 100% [2]. It has long been recognized that prolonged use of electronic screens results in a variety of visual symptoms in a considerable proportion of users (56%, range 25%–93%, according to a review of nine studies published between 1974 and 19933, or 64–90% according to a more recent review [2]). The reported symptoms include eyestrain, headaches, ocular discomfort, dry eye, diplopia (double vision) and blurred vision. Taken together, these symptoms are referred to as computer vision syndrome (CVS). Some authors consider CVS to be synonymous with asthenopia [4], whereas others consider asthenopia synonymous with eyestrain and thus one of the symptoms of CVS. Regardless of the definition, eye- strain (or asthenopia in the narrow sense) is the main parameter used to quantitate the prevalence of CVS [5].

[endshort]

BENEFITS OF ZEALUT-DENA (LUTEIN AND ZEAXANTHIN) IN SUBJECTS WITH COMPUTER VISION SYNDROME

According to a survey conducted more than a decade ago, more than half of the working population used computers at that time [1], and the proportion of people using various electronic screens for work and in everyday life is thought to be now close to 100% [2]. It has long been recognized that prolonged use of electronic screens results in a variety of visual symptoms in a considerable proportion of users (56%, range 25%–93%, according to a review of nine studies published between 1974 and 19933, or 64–90% according to a more recent review [2]). The reported symptoms include eyestrain, headaches, ocular discomfort, dry eye, diplopia (double vision) and blurred vision. Taken together, these symptoms are referred to as computer vision syndrome (CVS). Some authors consider CVS to be synonymous with asthenopia [4], whereas others consider asthenopia synonymous with eyestrain and thus one of the symptoms of CVS. Regardless of the definition, eye- strain (or asthenopia in the narrow sense) is the main parameter used to quantitate the prevalence of CVS [5].

 

Although computer screens do not emit the particularly damaging UV light, they do emit blue light, which is also damaging to the retina [6] and might be one of the factors in CVS development. In particular, light emitted by light-emitting diodes (LED), which are used in recent models of computer monitors, has been found to be damaging to the retina, presumably because of oxidative stress from reactive oxygen species this light generates [7].

 

The carotenoids lutein and zeaxanthin are thought to have a dual protective effect: they filter out the most damaging irradiation (blue light and UV), and they scavenge reactive oxygen species. Although most lutein and zeaxanthin in the eye is concentrated in the retina (especially in the macula), they are the only carotenoid species present in the lens [8, 9]. Multiple carotenoid species are present in blood plasma, but only lutein and zeaxanthin are able to cross the hemato-ophthalmic barrier and accumulate in the eye tissues, including the retina, where their concentration is four orders of magnitude higher than in the blood [10, 11]. Dietary supplementation is an efficient way to increase the content of these carotenoids in the eye, especially in individuals with poor diet who receive insufficient amounts of lutein and zeaxanthin with food, as concluded by AREDS2, a large multicenter study conducted in 2006–2012 [12, 13]. The content of lutein and zeaxanthin in the eye tissues follows changes in the dietary intake of these carotenoids with a delay of two to three weeks [14]. The data from several studies shed light on the potential ability of lutein and zeaxanthin supplementation to alleviate CVS symptoms.

 

Circumstantial evidence comes from a study conducted in Finland, which reported a beneficial effect of sea buckthorn oil in individuals with dry eye [15], which is one of the CVS symptoms. This natural product contains zeaxanthin, among other ingredients, however the effects of individual ingredients have not been investigated.

 

A small-scale (13 participants) randomized, double-blind, placebo-controlled study conducted in Japan assessed the effects of a supplement containing lutein and zeaxanthin (5 mg and 1 mg, respectively, i.e. the amounts corresponding to half of a Zealut-Dena capsule) and blackcurrant extract (200 mg) [16]. The supplement or a placebo was given to the participants for two weeks, followed by two weeks of washout and then by two more weeks of the opposite treatment. Eye fatigue was measured by using subjective fatigue and stress scores as well as objective approaches such as electroencephalography, electrooculography and measuring the eye fixation-related potential. The study found significant differences between the supplement and placebo and concluded that the tested supplement can be used to reduce the symptoms of visual fatigue [16]. Notably, the observed effects were quite rapid in comparison with the beneficial effects of lutein and zeaxanthin in patients with such eye diseases as retinitis pigmentosa [17], diabetic retinopathy [18] or age-related macular degeneration [19]. A limitation of this trial was that the contributions of individual components (i.e., lutein, zeaxanthin and blackcurrant extract) were not tested.

 

The positive effect of lutein was ascertained by a study by Ma and co-workers [20], which involved 37 relatively young (22–30 years old) healthy participants who had been using computers for >10h a day over the previous two years. The participants were given either placebo or lutein (6 or 12 mg daily) for 12 weeks. The study found a significant and dose-dependent improvement in contrast sensitivity in the lutein groups. A slight improvement in visual acuity in both lutein groups was also observed, although this effect did not reach statistical significance.

 

Overall, although information on the benefits of lutein and zeaxanthin supplementation for CVS sufferers is so far limited and more detailed studies need to be conducted, the data available to date indicate that these carotenoids (or at least lutein) alleviate the CVS symptoms. As average dietary consumption of lutein plus zeaxanthin in the USA is estimated at only 1.7 mg/day, American Optometric Association currently recommends taking supplements that increase the intake to >6  mg/day [21]. In this respect, taking even one capsule of Zealut-Dena daily (i.e., 11 mg lutein plus zeaxanthin) is expected to be sufficient to mitigate any deficit of lutein and zeaxanthin intake with food. It should be also noted that the safety of long-term lutein and zeaxanthin supplementation has been confirmed [22, 23].

 

References

  1. United States Department of Labor, Bureau of Labor Statistics. Computer and internet use at work summary. http://www.bls.gov/news.release/ciuaw.nr0.htm (2003).
  2. Rosenfield, M. Computer vision syndrome: a review of ocular causes and potential treatments. Ophthalmic Physiol Opt 31, 502-515 (2011).
  3. Thomson, W.D. Eye problems and visual display terminals--the facts and the fallacies. Ophthalmic Physiol Opt 18, 111-119 (1998).
  4. Ostrovsky, A., Ribak, J., Pereg, A. & Gaton, D. Effects of job-related stress and burnout on asthenopia among high-tech workers. Ergonomics 55, 854-862 (2012).
  5. Portello, J.K., Rosenfield, M., Bababekova, Y., Estrada, J.M. & Leon, A. Computer-related visual symptoms in office workers. Ophthalmic Physiol Opt 32, 375-382 (2012).
  6. Youssef, P.N., Sheibani, N. & Albert, D.M. Retinal light toxicity. Eye (Lond) 25, 1-14 (2011).
  7. Lougheed, T. Hidden blue hazard? Environ Health Perspect 122, A81 (2014).
  8. Bernstein, P.S. et al. Identification and quantitation of carotenoids and their metabolites in the tissues of the human eye. Exp Eye Res 72, 215-223 (2001).
  9. Yeum, K.J., Shang, F.M., Schalch, W.M., Russell, R.M. & Taylor, A. Fat-soluble nutrient concentrations in different layers of human cataractous lens. Curr Eye Res 19, 502-505 (1999).
  10. Stringham, J.M. & Hammond, B.R., Jr. Dietary lutein and zeaxanthin: possible effects on visual function. Nutr Rev 63, 59-64 (2005).
  11. Whitehead, A.J., Mares, J.A. & Danis, R.P. Macular pigment: a review of current knowledge. Arch Ophthalmol 124, 1038-1045 (2006).
  12. Andreatta, W. & El-Sherbiny, S. Evidence-based nutritional advice for patients affected by age-related macular degeneration. Ophthalmologica 231, 185-190 (2014).
  13. Pinazo-Duran, M.D. et al. Do nutritional supplements have a role in age macular degeneration prevention? J Ophthalmol 2014, 901686 (2014).
  14. Loughman, J., Nolan, J.M. & Beatty, S. Impact of dietary carotenoid deprivation on macular pigment and serum concentrations of lutein and zeaxanthin. Br J Nutr 108, 2102-2103 (2012).
  15. Larmo, P.S. et al. Oral sea buckthorn oil attenuates tear film osmolarity and symptoms in individuals with dry eye. J Nutr 140, 1462-1468 (2010).
  16. Yagi, A. et al. The effect of lutein supplementation on visual fatigue: a psychophysiological analysis. Appl Ergon 40, 1047-1054 (2009).
  17. Dagnelie, G., Zorge, I.S. & McDonald, T.M. Lutein improves visual function in some patients with retinal degeneration: a pilot study via the Internet. Optometry 71, 147-164 (2000).
  18. Hu, B.J., Hu, Y.N., Lin, S., Ma, W.J. & Li, X.R. Application of Lutein and Zeaxanthin in nonproliferative diabetic retinopathy. Int J Ophthalmol 4, 303-306 (2011).
  19. Ma, L. et al. Effect of lutein and zeaxanthin on macular pigment and visual function in patients with early age-related macular degeneration. Ophthalmology 119, 2290-2297 (2012).
  20. Ma, L. et al. A 12-week lutein supplementation improves visual function in Chinese people with long-term computer display light exposure. Br J Nutr 102, 186-190 (2009).
  21. American Optometric Association. Lutein and Zeaxanthin - Eye-Friendly Nutrients. http://www.aoa.org/patients-and-public/caring-for-your-vision/nutrition/lutein-and-zeaxanthin?sso=y
  22. Bahrami, H., Melia, M. & Dagnelie, G. Lutein supplementation in retinitis pigmentosa: PC-based vision assessment in a randomized double-masked placebo-controlled clinical trial [NCT00029289]. BMC Ophthalmol 6, 23 (2006).
  23. Berson, E.L. et al. Clinical trial of lutein in patients with retinitis pigmentosa receiving vitamin A. Arch Ophthalmol 128, 403-411 (2010).

[endmore]

[more]

 

POTENTIAL BENEFITS OF ZEALUT-DENA (LUTEIN AND ZEAXANTHIN) IN INDIVIDUALS EXPOSED TO BRIGHT LIGHT

Excessive light is known to damage the retina [1], in particular by inducing apoptosis (cell death) of photoreceptor cells [2] and causing complex post-exposure retinal remodeling, which eventually becomes irreversible [3]. Excessive light is particularly damaging in patients with degenerative retinal diseases because it synergistically accelerates photoreceptor cell death [3]. Damage caused by bright light and by these diseases may involve similar mechanisms, because late-stage retinal remodeling after light damage is similar to the anatomical changes observed in advanced age-related macular degeneration (AMD) [4]. Collectively, retinal damage from bright light is known as solar retinopathy, or solar retinitis, regardless of whether it is caused by sunlight or an artificial source of bright light, such as welding arc [5].

[endshort]

POTENTIAL BENEFITS OF ZEALUT-DENA (LUTEIN AND ZEAXANTHIN) IN INDIVIDUALS EXPOSED TO BRIGHT LIGHT

Excessive light is known to damage the retina [1], in particular by inducing apoptosis (cell death) of photoreceptor cells [2] and causing complex post-exposure retinal remodeling, which eventually becomes irreversible [3]. Excessive light is particularly damaging in patients with degenerative retinal diseases because it synergistically accelerates photoreceptor cell death [3]. Damage caused by bright light and by these diseases may involve similar mechanisms, because late-stage retinal remodeling after light damage is similar to the anatomical changes observed in advanced age-related macular degeneration (AMD) [4]. Collectively, retinal damage from bright light is known as solar retinopathy, or solar retinitis, regardless of whether it is caused by sunlight or an artificial source of bright light [5].

 

Sunlight exposure is a known risk factor for AMD [6]. A detailed study conducted among 838 boat workers in Chesapeake Bay (Maryland and Virginia), analyzed the effects of exposure to different wavelengths of visible light (400–450 nm, 400–500 nm, and all visible light, 400–700 nm) and UV (UV-A, 320–340 nm; UV-B, 290–320 nm) over 20 years on the development of eye diseases, including AMD [7]. The authors found that exposure to visible light (400–500 nm or 400–700 nm) but not to UV light was significantly associated with advanced AMD. Analysis of the results of the 5-year Beaver Dam Eye Study (conducted in Wisconsin) obtained between 1987 and 1990 found that exposure to sunlight (as estimated from the amount of time spent outdoors in summer) was positively associated with advanced AMD, whereas the use of hats with brims and sunglasses protected against AMD [8].

 

The National Health and Nutrition Survey, conducted in 1971–1974, revealed a positive association between cataract extraction without implantation of an ultraviolet/blue light absorbing intraocular lens and AMD development, apparently because of an increase in retina exposure to harmful irradiation in the absence of the lens [9]. Exposure to sunlight, especially to its UV component, promotes oxidation of lens proteins and plays an important role in cataract development [10, 11].

 

Thus, exposure to excessively bright light is a risk factor in the development of both AMD and cataract; in both cases induction of reactive oxygen species appears to play a role [12]. Although artificial light sources do not emit UV light (unless they are specifically designed to do so), they do emit blue light, which may damage the retina [13]. In particular, light emitted by light-emitting diodes (LED) used in some modern energy-efficient light bulbs has been found to be damaging to the retina, presumably because of oxidative stress from reactive oxygen species this light generates [14].

 

The carotenoids lutein and zeaxanthin are thought to have protective effects in the retina [15] thanks to their ability to filter out most damaging irradiation [16, 17] and to scavenge reactive oxygen species [18]; they may also have anti-inflammatory effects in the retina [19]. Although most lutein and zeaxanthin in the eye is concentrated in the retina (especially in the macula), they are the only carotenoid species present in the lens [20, 21]. These carotenoids efficiently protect human lens epithelial cells against UVB-induced damage [22].

 

Multiple carotenoid species are present in blood plasma, but only lutein and zeaxanthin are able to cross the hemato-ophthalmic barrier and accumulate in the eye tissues, including the retina, where their concentration is four orders of magnitude higher than in the blood [11, 23]. Dietary supplementation is an efficient way to increase the content of these carotenoids in the eye, especially in individuals with poor diet who receive insufficient amounts of lutein and zeaxanthin with food, as concluded by AREDS2 (The Age-Related Eye Disease Study 2), a large multicenter study conducted in 2006–2012 [24, 25]. The content of lutein and zeaxanthin in the eye tissues follows changes in the dietary intake of these carotenoids with a delay of two to three weeks [26].

 

The data from a number of studies demonstrate beneficial effects of lutein and zeaxanthin supplementation in patients with AMD and their association with reduced risk of cataract development. For example, two independent studies found that daily intake of lutein and/or zeaxanthin significantly improves contrast sensitivity in patients with early AMD [27, 28]. The AREDS2 study revealed a protective effect of lutein and zeaxanthin against the onset of AMD in subjects whose dietary intake of these carotenoids was within the lowest quintile [24, 29]. Although this study did not assess the contribution of bright light into the onset of AMD in participants, these results consider together with the fact that light is a risk factor for the onset of AMD are compatible with the ability of lutein and zeaxanthin supplementation to mitigate the harmful effect of light on the macula. Lutein (10 mg/day) and zeaxanthin (2 mg/day) have been recommended as components of the AREDS formulation [30].

 

The Beaver Dam Eye Study mentioned above found that lutein and zeaxanthin were the only carotenoids associated with the reduced risk of nuclear cataract development: their intake in the highest quintile reportedly reduced the risk by as much as half [31]. These results suggested a protective effect of these carotenoids in individuals at risk of cataract development and were corroborated by two larger-scale studies conducted in the last quarter of the 20th century. The Nurses’ Health Study, which enrolled female registered nurses, found that increased intake of lutein (≥6 mg/day) and zeaxanthin reduced the number of required cataract surgeries [32]. The parallel Health Professionals Follow-Up Study, which enrolled male health professionals, reported similar result. This study found a decrease in the need for cataract surgeries as a result of increased intake of lutein and zeaxanthin (6.9 mg/day) [33]. A recent meta-analysis of 13 observational studies (18,999 participants in total) concluded that the blood levels of both lutein and zeaxanthin (the two carotenoid species were analyzed separately) are inversely associated with risk of age-related cataract [34]. As in the case of AMD, since sunlight increases the risk of cataract development, these data are compatible with the ability of lutein and zeaxanthin supplementation to mitigate the effect of sunlight on the lens.

 

Overall, although studies to directly assess the benefits of lutein and zeaxanthin supplementation in humans exposed to bright light (either sunlight or light from artificial sources) are yet to be conducted, the facts that (1) bright light increases the risk of AMD and cataract and (2) lutein and zeaxanthin supplementation has positive effects in patients with both diseases make it reasonable to recommend supplementation with these carotenoids in individuals whose lifestyle or profession results in an increased exposure of their eyes to potentially damaging light levels, at least as an appropriate cautionary measure. This may be especially important for individuals with low dietary intake of these carotenoids [24, 29]. As average dietary consumption of lutein plus zeaxanthin in the USA is estimated at only 1.7 mg/day, the American Optometric Association currently recommends taking supplements that increase the intake to >6 mg/day [35]. In this respect, taking even one capsule of Zealut-Dena daily (i.e.: 11 mg lutein plus zeaxanthin) is expected to be sufficient to mitigate any deficit of lutein and zeaxanthin intake with food. It should be also noted that the safety of long-term lutein and zeaxanthin supplementation has been confirmed [36, 37].

 

References

  1. Ham, W.T., Jr. Ocular hazards of light sources: review of current knowledge. J Occup Med 25, 101-103 (1983).
  2. Wenzel, A., Grimm, C., Samardzija, M. & Reme, C.E. Molecular mechanisms of light-induced photoreceptor apoptosis and neuroprotection for retinal degeneration. Prog Retin Eye Res 24, 275-306 (2005).
  3. Organisciak, D.T. & Vaughan, D.K. Retinal light damage: mechanisms and protection. Prog Retin Eye Res 29, 113-134 (2010).
  4. Marc, R.E. et al. Extreme retinal remodeling triggered by light damage: implications for age related macular degeneration. Mol Vis14, 782-806 (2008).
  5. Chen, K.C., Jung, J.J. & Aizman, A. Solar retinopathy: etiology, diagnosis, and treatment. Retinal Physician 10, 46-50 (2013).
  6. Snodderly, D.M. Evidence for protection against age-related macular degeneration by carotenoids and antioxidant vitamins. Am J Clin Nutr 62, 1448S-1461S (1995).
  7. Taylor, H.R. et al. The long-term effects of visible light on the eye. Arch Ophthalmol 110, 99-104 (1992).
  8. Cruickshanks, K.J., Klein, R. & Klein, B.E. Sunlight and age-related macular degeneration. The Beaver Dam Eye Study. Arch Ophthalmol 111, 514-518 (1993).
  9. Liu, I.Y., White, L. & LaCroix, A.Z. The association of age-related macular degeneration and lens opacities in the aged. Am J Public Health 79, 765-769 (1989).
  10. Sliney, D.H. UV radiation ocular exposure dosimetry. J Photochem Photobiol B 31, 69-77 (1995).
  11. Stringham, J.M. & Hammond, B.R., Jr. Dietary lutein and zeaxanthin: possible effects on visual function. Nutr Rev 63, 59-64 (2005).
  12. Glickman, R.D. Ultraviolet phototoxicity to the retina. Eye Contact Lens 37, 196-205 (2011).
  13. Youssef, P.N., Sheibani, N. & Albert, D.M. Retinal light toxicity. Eye (Lond) 25, 1-14 (2011).
  14. Lougheed, T. Hidden blue hazard? Environ Health Perspect 122, A81 (2014).
  15. Stahl, W. Macular carotenoids: lutein and zeaxanthin. Dev Ophthalmol 38, 70-88 (2005).
  16. Junghans, A., Sies, H. & Stahl, W. Macular pigments lutein and zeaxanthin as blue light filters studied in liposomes. Arch Biochem Biophys 391, 160-164 (2001).
  17. Krinsky, N.I., Landrum, J.T. & Bone, R.A. Biologic mechanisms of the protective role of lutein and zeaxanthin in the eye. Annu Rev Nutr 23, 171-201 (2003).
  18. Ahmed, S.S., Lott, M.N. & Marcus, D.M. The macular xanthophylls. Surv Ophthalmol 50, 183-193 (2005).
  19. Izumi-Nagai, K. et al. Macular pigment lutein is antiinflammatory in preventing choroidal neovascularization. Arterioscler Thromb Vasc Biol 27, 2555-2562 (2007).
  20. Bernstein, P.S. et al. Identification and quantitation of carotenoids and their metabolites in the tissues of the human eye. Exp Eye Res 72, 215-223 (2001).
  21. Yeum, K.J., Shang, F.M., Schalch, W.M., Russell, R.M. & Taylor, A. Fat-soluble nutrient concentrations in different layers of human cataractous lens. Curr Eye Res 19, 502-505 (1999).
  22. Chitchumroonchokchai, C., Bomser, J.A., Glamm, J.E. & Failla, M.L. Xanthophylls and alpha-tocopherol decrease UVB-induced lipid peroxidation and stress signaling in human lens epithelial cells. J Nutr 134, 3225-3232 (2004).
  23. Whitehead, A.J., Mares, J.A. & Danis, R.P. Macular pigment: a review of current knowledge. Arch Ophthalmol 124, 1038-1045 (2006).
  24. Andreatta, W. & El-Sherbiny, S. Evidence-based nutritional advice for patients affected by age-related macular degeneration. Ophthalmologica 231, 185-190 (2014).
  25. Pinazo-Duran, M.D. et al. Do nutritional supplements have a role in age macular degeneration prevention? J Ophthalmol 2014, 901686 (2014).
  26. Loughman, J., Nolan, J.M. & Beatty, S. Impact of dietary carotenoid deprivation on macular pigment and serum concentrations of lutein and zeaxanthin. Br J Nutr 108, 2102-2103 (2012).
  27. Ma, L. et al. Effect of lutein and zeaxanthin on macular pigment and visual function in patients with early age-related macular degeneration. Ophthalmology 119, 2290-2297 (2012).
  28. Sabour-Pickett, S. et al. Supplementation with three different macular carotenoid formulations in patients with early age-related macular degeneration. Retina (2014).
  29. Pinazo-Duran, M.D. et al. Oxidative stress and its downstream signaling in aging eyes. Clin Interv Aging 9, 637-652 (2014).
  30. Group, T.A.-R.E.D.S.A.R. Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration: the Age-Related Eye Disease Study 2 (AREDS2) randomized clinical trial. JAMA 309, 2005-2015 (2013).
  31. Lyle, B.J., Mares-Perlman, J.A., Klein, B.E., Klein, R. & Greger, J.L. Antioxidant intake and risk of incident age-related nuclear cataracts in the Beaver Dam Eye Study. Am J Epidemiol 149, 801-809 (1999).
  32. Chasan-Taber, L. et al. A prospective study of carotenoid and vitamin A intakes and risk of cataract extraction in US women. Am J Clin Nutr 70, 509-516 (1999).
  33. Brown, L. et al. A prospective study of carotenoid intake and risk of cataract extraction in US men. Am J Clin Nutr 70, 517-524 (1999).
  34. Cui, Y.H., Jing, C.X. & Pan, H.W. Association of blood antioxidants and vitamins with risk of age-related cataract: a meta-analysis of observational studies. Am J Clin Nutr 98, 778-786 (2013).
  35. American Optometric Association. Lutein and Zeaxanthin - Eye-Friendly Nutrients. http://www.aoa.org/patients-and-public/caring-for-your-vision/nutrition/lutein-and-zeaxanthin?sso=y
  36. Bahrami, H., Melia, M. & Dagnelie, G. Lutein supplementation in retinitis pigmentosa: PC-based vision assessment in a randomized double-masked placebo-controlled clinical trial [NCT00029289]. BMC Ophthalmol 6, 23 (2006).
  37. Berson, E.L. et al. Clinical trial of lutein in patients with retinitis pigmentosa receiving vitamin A. Arch Ophthalmol 128, 403-411 (2010).

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BENEFITS OF ZEALUT-DENA (LUTEIN AND ZEAXANTHIN) INTAKE IN SUBJECTS AT RISK OF CATARACT DEVELOPMENT

Oxidative stress is known to contribute to the onset and progression of a number of eye diseases [1]. Cataracts, along with age-related macular degeneration, are a major cause of blindness in the elderly. Oxidative stress, especially that caused by UV light, plays an important role in cataract development by promoting oxidation of lens proteins [2, 3]. The carotenoids lutein and zeaxanthin are thought have a dual protective effect: they filter out the most damaging short-wavelength irradiation (blue light and UV) and scavenge reactive oxygen species. Although most lutein and zeaxanthin in the eye is concentrated in the retina (especially in the macula), they are the only carotenoid species present in the lens [4, 5]. Over the last ~30 years, a number of studies have been conducted to determine whether lutein and zeaxanthin may reduce the risk of age-related cataracts.

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BENEFITS OF ZEALUT-DENA (LUTEIN AND ZEAXANTHIN) INTAKE IN SUBJECTS AT RISK OF CATARACT DEVELOPMENT

Oxidative stress is known to contribute to the onset and progression of a number of eye diseases [1]. Cataracts, along with age-related macular degeneration, are a major cause of blindness in the elderly. Oxidative stress, especially that caused by UV light, plays an important role in cataract development by promoting oxidation of lens proteins [2, 3]. The carotenoids lutein and zeaxanthin are thought have a dual protective effect: they filter out the most damaging short-wavelength irradiation (blue light and UV) and scavenge reactive oxygen species. Although most lutein and zeaxanthin in the eye is concentrated in the retina (especially in the macula), they are the only carotenoid species present in the lens [4, 5]. Over the last ~30 years, a number of studies have been conducted to determine whether lutein and zeaxanthin may reduce the risk of age-related cataracts.

 

The 5-year Beaver Dam Eye Study, which enrolled 1354 subjects and was conducted between 1988 and 1995, found that lutein and zeaxanthin were the only carotenoids associated with the reduced risk of nuclear cataract development: their intake in the highest quintile reportedly reduced the risk by as much as half 6. These results were corroborated by two larger-scale studies. The Nurses’ Health Study, which was conducted in the USA and enrolled female registered nurses, found that increased intake of lutein (≥6 mg/day) and zeaxanthin reduced the number of required cataract surgeries [7]. The parallel Health Professionals Follow-Up Study, which enrolled male health professionals, reported similar results: this study found a decrease in the need for cataract surgeries as a result of increased intake of lutein and zeaxanthin (6.9 mg/day) [8]. However, some other studies at that time failed to find a significant association between cataract risk and carotenoid supplementation, and a Food and Drug Administration review conducted in 2006 concluded that there was no reliable evidence for the ability of lutein and zeaxanthin to reduce the risk of cataracts [9]. Nevertheless, a number of other studies published the same year and later have confirmed the beneficial effects of one or both of these carotenoids with respect to cataract development.

 

The results of two studies, also published in 2006, may shed light on possible reasons for the above discrepancies. The POLA study (Pathologies Oculaires Liées à l’Age – Age-Related Eye Pathologies), which was conducted in France and Switzerland and enrolled 2584 participants, found a significant association between high plasma levels of zeaxanthin and a reduced risk of any cataracts and specifically nuclear cataracts [10]. Yet, no significant association was found between the risk of cataracts and either combined plasma lutein and zeaxanthin or lutein alone [10]. These results suggest that zeaxanthin may be more important than lutein in protecting the lens from cataract development. If so, the discrepancies between earlier studies could be due to the fact that dietary intake of zeaxanthin and its natural content in ocular tissues is only 10–20% of that of lutein [11, 12] (this natural proportion is taken into account in the Zealut-Dena formulation: 10 mg lutein and 1 mg zeaxanthin). Therefore, any specific effects of zeaxanthin would be more challenging to measure than those of lutein or both carotenoids combined.

 

The Melbourne Visual Impairment Project, which analyzed separately the incidence of cortical, nuclear, and posterior subcapsular cataracts in 1,841, 1,955, and 1,950 subjects, respectively, over a period of three to seven years, reported an inverse association between high dietary intake of lutein and zeaxanthin and prevalence of nuclear cataract, but not of the other two cataract types [13]. Although nuclear cataract is the prevalent type (more than half of total cataract cases in the Melbourne Visual Impairment Project were represented by this type [13]), the absence of the effect on other cataract types may have been another confounding factor in earlier studies.

 

The Carotenoids in Age-Related Eye Disease Study (CAREDS), a multi-center study conducted in the USA and supported by the National Eye Institute and Research to Prevent Blindness, enrolled 1,802 women over 50 who had the highest percentile (>78%) or the lowest percentile (<28%) of lutein and zeaxanthin intake according to the data from an earlier study in which they participated [14, 15]. The CAREDS study found that women with the highest intake of both carotenoids were 32% less likely to have nuclear cataract (the only cataract type assessed) than women with the lowest intake. A similar but weaker association was found in women who took lutein-only supplement [14], which is in line with the conclusion of the POLA study [10] that zeaxanthin may have a stronger beneficial effect than lutein.

 

A study conducted in Finland investigated the association between the plasma levels of lutein and zeaxanthin in 1,689 elderly subjects (aged 61–80 years) and the risk of nuclear cataract (only five out of 113 age-related cataracts in this study were of other types) [16]. This study found that subjects who had the highest percentile (>75%) of plasma concentrations of lutein and zeaxanthin had 42% and 41% lower risks of nuclear cataract, respectively, in comparison with those who had the lowest percentile (<25%). Thus, this study confirmed the beneficial effect of these carotenoids but did not reveal any differential effects of lutein and zeaxanthin.

 

The availability of data from multiple studies on the association between lutein and zeaxanthin and the risk of cataract development makes it now possible to perform meta-analyses across different studies. Three such meta-analyses were published in 2013–2014. On the basis of meta-analysis of 13 observational studies (18,999 participants in total), Cui and coworkers [17] concluded that blood levels of both lutein and zeaxanthin (the two carotenoid species were analyzed separately), but not those of three other carotenoids (β-carotene, lycopene, and β-cryptoxanthin), are inversely associated with the risk of age-related cataract.

 

A meta-analysis of the results of one cohort study and seven cross-sectional studies confirmed that high concentrations of lutein and zeaxanthin in the blood are associated with a significantly reduced risk of nuclear cataract but probably not of other cataract types, although a marginally significant association between lutein and subcapsular cataract was noted [18]. In line with the conclusions of the POLA study, zeaxanthin was found to have a stronger effect, although only in European studies [18]. Finally, a meta-analysis of six prospective cohort studies (41,999 participants; 4,416 cataract cases) addressed not only the association between dietary lutein and zeaxanthin intake and the risk of age-related cataract, but also the dose-dependence of this association [19]. This meta-analysis confirmed a statistically significant association between the intake of these carotenoids and a reduced risk of nuclear cataract, but not of cortical and posterior subcapsular cataract. An increase of 0.3 mg/day in dietary lutein and zeaxanthin intake was found to be associated with a 3% reduction in the risk of nuclear cataract [19].

 

In conclusion, despite some doubts and inconsistencies in the results of earlier studies, it is now firmly established that increased intake of lutein and zeaxanthin is associated with a reduced risk of nuclear cataract; to what extent these carotenoids may reduce the risk of other cataract types remains to be ascertained. As the average dietary consumption of lutein plus zeaxanthin in the USA is estimated at only 1.7 mg/day, the American Optometric Association currently recommends taking supplements that increase the intake to >6 mg/day [20]. In this respect, taking even one capsule of Zealut-Dena daily (i.e., 11 mg lutein plus zeaxanthin) is expected to reduce the risk of age-related nuclear cataract.

 

References

  1. Khandhadia, S. & Lotery, A. Oxidation and age-related macular degeneration: insights from molecular biology. Expert Rev Mol Med12, e34 (2010).
  2. Stringham, J.M. & Hammond, B.R., Jr. Dietary lutein and zeaxanthin: possible effects on visual function. Nutr Rev 63, 59-64 (2005).
  3. Sliney, D.H. UV radiation ocular exposure dosimetry. J Photochem Photobiol B 31, 69-77 (1995).
  4. Bernstein, P.S. et al. Identification and quantitation of carotenoids and their metabolites in the tissues of the human eye. Exp Eye Res 72, 215-223 (2001).
  5. Yeum, K.J., Shang, F.M., Schalch, W.M., Russell, R.M. & Taylor, A. Fat-soluble nutrient concentrations in different layers of human cataractous lens. Curr Eye Res 19, 502-505 (1999).
  6. Lyle, B.J., Mares-Perlman, J.A., Klein, B.E., Klein, R. & Greger, J.L. Antioxidant intake and risk of incident age-related nuclear cataracts in the Beaver Dam Eye Study. Am J Epidemiol 149, 801-809 (1999).
  7. Chasan-Taber, L. et al. A prospective study of carotenoid and vitamin A intakes and risk of cataract extraction in US women. Am J Clin Nutr 70, 509-516 (1999).
  8. Brown, L. et al. A prospective study of carotenoid intake and risk of cataract extraction in US men. Am J Clin Nutr 70, 517-524 (1999).
  9. Trumbo, P.R. & Ellwood, K.C. Lutein and zeaxanthin intakes and risk of age-related macular degeneration and cataracts: an evaluation using the Food and Drug Administration's evidence-based review system for health claims. Am J Clin Nutr 84, 971-974 (2006).
  10. Delcourt, C., Carriere, I., Delage, M., Barberger-Gateau, P. & Schalch, W. Plasma lutein and zeaxanthin and other carotenoids as modifiable risk factors for age-related maculopathy and cataract: the POLA Study. Invest Ophthalmol Vis Sci 47, 2329-2335 (2006).
  11. Seddon, J.M. et al. Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. Eye Disease Case-Control Study Group. JAMA 272, 1413-1420 (1994).
  12. Thurmann, P.A., Schalch, W., Aebischer, J.C., Tenter, U. & Cohn, W. Plasma kinetics of lutein, zeaxanthin, and 3-dehydro-lutein after multiple oral doses of a lutein supplement. Am J Clin Nutr 82, 88-97 (2005).
  13. Vu, H.T., Robman, L., Hodge, A., McCarty, C.A. & Taylor, H.R. Lutein and zeaxanthin and the risk of cataract: the Melbourne visual impairment project. Invest Ophthalmol Vis Sci 47, 3783-3786 (2006).
  14. Mares, J.A. et al. Associations between age-related nuclear cataract and lutein and zeaxanthin in the diet and serum in the Carotenoids in the Age-Related Eye Disease Study, an Ancillary Study of the Women's Health Initiative. Invest Ophthalmol Vis Sci 47, E-Abstract 4724 (2006).
  15. Moeller, S.M. et al. Associations between age-related nuclear cataract and lutein and zeaxanthin in the diet and serum in the Carotenoids in the Age-Related Eye Disease Study, an Ancillary Study of the Women's Health Initiative. Arch Ophthalmol 126, 354-364 (2008).
  16. Karppi, J., Laukkanen, J.A. & Kurl, S. Plasma lutein and zeaxanthin and the risk of age-related nuclear cataract among the elderly Finnish population. Br J Nutr 108, 148-154 (2012).
  17. Cui, Y.H., Jing, C.X. & Pan, H.W. Association of blood antioxidants and vitamins with risk of age-related cataract: a meta-analysis of observational studies. Am J Clin Nutr 98, 778-786 (2013).
  18. Liu, X.H. et al. Association between lutein and zeaxanthin status and the risk of cataract: a meta-analysis. Nutrients 6, 452-465 (2014).
  19. Ma, L. et al. A dose-response meta-analysis of dietary lutein and zeaxanthin intake in relation to risk of age-related cataract. Graefes Arch Clin Exp Ophthalmol 252, 63-70 (2014).
  20. American Optometric Association. Lutein and Zeaxanthin - Eye-Friendly Nutrients. http://www.aoa.org/patients-and-public/caring-for-your-vision/nutrition/lutein-and-zeaxanthin?sso=y

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