zeaxanthin and Eye-Diseases

The human macula uniquely concentrates three carotenoids: lutein, zeaxanthin, and meso-zeaxanthin. Lutein and zeaxanthin must be obtained from dietary sources such as green leafy vegetables and orange and yellow fruits and vegetables, while meso-zeaxanthin is rarely found in diet and is believed to be formed at the macula by metabolic transformations of ingested carotenoids. Epidemiological studies and large-scale clinical trials such as AREDS2 have brought attention to the potential ocular health and functional benefits of these three xanthophyll carotenoids consumed through the diet or supplements, but the basic science and clinical research underlying recommendations for nutritional interventions against age-related macular degeneration and other eye diseases are underappreciated by clinicians and vision researchers alike. In this review article, we first examine the chemistry, biochemistry, biophysics, and physiology of these yellow pigments that are specifically concentrated in the macula lutea through the means of high-affinity binding proteins and specialized transport and metabolic proteins where they play important roles as short-wavelength (blue) light-absorbers and localized, efficient antioxidants in a region at high risk for light-induced oxidative stress. Next, we turn to clinical evidence supporting functional benefits of these carotenoids in normal eyes and for their potential protective actions against ocular disease from infancy to old age.

Topics: Animals; Antioxidants; Diet; Eye Diseases; Haplorhini; Humans; Lutein; Macula Lutea; Macular Degeneration; Retinal Pigments; Zeaxanthins

Current evidence suggests lutein and its isomers play important roles in ocular development in utero and throughout the life span, in vision performance in young and later adulthood, and in lowering risk for the development of common age-related eye diseases in older age. These xanthophyll (oxygen-containing) carotenoids are found in a wide variety of vegetables and fruits, and they are present in especially high concentrations in leafy green vegetables. Additionally, egg yolks and human milk appear to be bioavailable sources. The prevalence of lutein, zeaxanthin, and meso-zeaxanthin in supplements is increasing. Setting optimal and safe ranges of intake requires additional research, particularly in pregnant and lactating women. Accumulating evidence about variable interindividual response to dietary intake of these carotenoids, based on genetic or metabolic influences, suggests that there may be subgroups that benefit from higher levels of intake and/or alternate strategies to improve lutein and zeaxanthin status.

Topics: Age Factors; Animals; Anti-Inflammatory Agents, Non-Steroidal; Antioxidants; Diet, Healthy; Dietary Supplements; Eye Diseases; Humans; Lutein; Models, Biological; Organ Specificity; Oxidative Stress; Retina; Stereoisomerism; Vision Disorders; Zeaxanthins

The relationship between lutein and zeaxanthin and visual and cognitive health throughout the lifespan is compelling. There is a variety of evidence to support a role for lutein and zeaxanthin in vision. Lutein's role in cognition has only recently been considered. Lutein and its isomer, zeaxanthin, are taken up selectively into eye tissue. Lutein is the predominant carotenoid in human brain tissue. Lutein and zeaxanthin in neural tissue may have biological effects that include antioxidation, anti-inflammation, and structural actions. In addition, lutein and zeaxanthin may be protective against eye disease because they absorb damaging blue light that enters the eye. In pediatric brains, the relative contribution of lutein to the total carotenoids is twice that found in adults, accounting for more than half the concentration of total carotenoids. The greater proportion of lutein in the pediatric brain suggests a need for lutein during neural development as well. In adults, higher lutein status is related to better cognitive performance, and lutein supplementation improves cognition. The evidence to date warrants further investigation into the role of lutein and zeaxanthin in visual and cognitive health throughout the lifespan.

Topics: Adult; Animals; Child; Cognition; Dietary Supplements; Eye Diseases; Fruit; Humans; Lutein; Retina; Vegetables; Vision, Ocular; Xanthophylls; Zeaxanthins

Topics: Administration, Ophthalmic; Antioxidants; beta Carotene; Carotenoids; Cryptoxanthins; Eye Diseases; Female; Fruit; Humans; Lutein; Lycopene; Male; Neoplasms; Osteoporosis; Vegetables; Xanthophylls; Zeaxanthins

The lens and retina of the human eye are exposed constantly to light and oxygen. In situ phototransduction and oxidative phosphorylation within photoreceptors produces a high level of phototoxic and oxidative related stress. Within the eye, the carotenoids lutein and zeaxanthin are present in high concentrations in contrast to other human tissues. We discuss the role of lutein and zeaxanthin in ameliorating light and oxygen damage, and preventing age-related cellular and tissue deterioration in the eye. Epidemiologic research shows an inverse association between levels of lutein and zeaxanthin in eye tissues and age related degenerative diseases such as macular degeneration (AMD) and cataracts. We examine the role of these carotenoids as blockers of blue-light damage and quenchers of oxygen free radicals. This article provides a review of possible mechanisms of lutein action at a cellular and molecular level. Our review offers insight into current clinical trials and experimental animal studies involving lutein, and possible role of nutritional intervention in common ocular diseases that cause blindness.

Topics: Aging; Animals; Cataract; Eye Diseases; Humans; Light; Lutein; Macular Degeneration; Oxidative Stress; Reactive Oxygen Species; Xanthophylls; Zeaxanthins

Carotenoid-based visual cues and roles of carotenoids in human vision are reviewed, with an emphasis on protection by zeaxanthin and lutein against vision loss, and dietary sources of zeaxanthin and lutein are summarized. In addition, attention is given to synergistic interactions of zeaxanthin and lutein with other dietary factors affecting human vision (such as antioxidant vitamins, phenolics, and poly-unsaturated fatty acids) and the emerging mechanisms of these interactions. Emphasis is given to lipid oxidation products serving as messengers with functions in gene regulation. Lastly, the photo-physics of light collection and photoprotection in photosynthesis and vision are compared and their common principles identified as possible targets of future research.

Topics: Antioxidants; Diet; Dietary Supplements; Eye; Eye Diseases; Fatty Acids, Unsaturated; Humans; Lutein; Nutritional Status; Phenol; Vitamins; Xanthophylls; Zeaxanthins

Lutein and zeaxanthin are members of the oxygenated carotenoids found particularly in egg yolks and dark-green leafy vegetables. A great deal of research has focused on their beneficial roles in eye health. The present article summarises the current literature related to the bioactivity of these carotenoids, emphasising their effects and possible mechanisms of action in relation to human eye health. Available evidence demonstrates that lutein and zeaxanthin are widely distributed in a number of body tissues and are uniquely concentrated in the retina and lens, indicating that each has a possible specific function in these two vital ocular tissues. Most of epidemiological studies and clinical trials support the notion that lutein and zeaxanthin have a potential role in the prevention and treatment of certain eye diseases such as age-related macular degeneration, cataract and retinitis pigmentosa. The biological mechanisms for the protective effects of these carotenoids may include powerful blue-light filtering activities and antioxidant properties. Although most studies point towards significant health benefits from lutein and zeaxanthin, further large-scale randomised supplementation trials are needed to define their effects on ocular function in health and disease.

Topics: Antioxidants; Eye; Eye Diseases; Humans; Lens, Crystalline; Light; Lutein; Retina; Tissue Distribution; Xanthophylls; Zeaxanthins

Cataracts, glaucoma, and age-related macular degeneration (AMD) are common causes of blindness in the elderly population of the United States. Additional risk factors include obesity, smoking, and inadequate antioxidant status. Phytochemicals, as antioxidants and anti-inflammatory agents, may help prevent or delay the progression of these eye diseases. Observational and clinical trials support the safety of higher intakes of the phytochemicals lutein and zeaxanthin and their association with reducing risks of cataracts in healthy postmenopausal women and improving clinical features of AMD in patients. Additional phytochemicals of emerging interest, like green tea catechins, anthocyanins, resveratrol, and Ginkgo biloba, shown to ameliorate ocular oxidative stress, deserve more attention in future clinical trials.

Topics: Aged; Aging; Antioxidants; Cataract; Eye Diseases; Flavonoids; Glaucoma; Humans; Lutein; Macular Degeneration; Middle Aged; Nutritional Physiological Phenomena; Oxidative Stress; Phytotherapy; Plants, Edible; Xanthophylls; Zeaxanthins

Based on extensive epidemiological observation, fruits and vegetables that are a rich source of carotenoids are thought to provide health benefits by decreasing the risk of various diseases, particularly certain cancers and eye diseases. The carotenoids that have been most studied in this regard are beta-carotene, lycopene, lutein and zeaxanthin. In part, the beneficial effects of carotenoids are thought to be due to their role as antioxidants. beta-Carotene may have added benefits due its ability to be converted to vitamin A. Additionally, lutein and zeaxanthin may be protective in eye disease because they absorb damaging blue light that enters the eye. Food sources of these compounds include a variety of fruits and vegetables, although the primary sources of lycopene are tomato and tomato products. Additionally, egg yolk is a highly bioavailable source of lutein and zeaxanthin. These carotenoids are available in supplement form. However, intervention trials with large doses of beta-carotene found an adverse effect on the incidence of lung cancer in smokers and workers exposed to asbestos. Until the efficacy and safety of taking supplements containing these nutrients can be determined, current dietary recommendations of diets high in fruits and vegetables are advised.

Topics: Antioxidants; beta Carotene; Cardiovascular Diseases; Carotenoids; Diet; Eye Diseases; Free Radicals; Fruit; Humans; Lutein; Lycopene; Neoplasms; Vegetables; Xanthophylls; Zeaxanthins

Excessive consumption of energy and fat increases the risk for obesity. Snacks containing sucrose polyesters (SPE) as a dietary fat replacer are on the market in the United States. SPE products have been shown to lower concentrations of serum carotenoids in short-term studies. Experimental studies on the longer-term effects on health of decreased carotenoid concentrations are lacking. A 1-y randomized, double-blind, placebo-controlled parallel trial was performed. Subjects (n = 380) with a habitual low or high fruit and vegetable intake were assigned to the treatments (0, 7, 10 or 17 g/d SPE). SPE was given in the form of spreads, chips or both. The groups were compared for serum carotenoids, vitamins and markers of oxidative damage, eye health, cardiovascular health and immune status. After 1 y, serum lipid-adjusted carotenoids showed the largest decrease in the SPE chips and spread group (17 g/d) compared with the control group [alpha-carotene 33%; beta-carotene 31%, lycopene 24%, beta-cryptoxanthin 18%, lutein 18% (all P < 0.001) and zeaxanthin 13% (P < 0.05)]. Consumption of SPE spread (10 g/d SPE) decreased carotenoid concentrations by 11-29% (all P < 0.05). SPE chips (7 g/d SPE) decreased zeaxanthin (11%), beta-carotene (12%) and alpha-carotene (21%; all P < 0.05). Serum lipid adjusted alpha-tocopherol decreased significantly by 6-8% (all P < 0.001) in all SPE groups. No negative effects were observed on markers of oxidation, eye health, cardiovascular health or immune status. This study shows that decreases in serum carotenoid concentrations do not affect possible markers of disease risk.

Topics: Adolescent; Adult; Aged; alpha-Tocopherol; beta Carotene; Body Weight; Cardiovascular Diseases; Carotenoids; Dietary Fats, Unsaturated; Double-Blind Method; Endothelium, Vascular; Eye Diseases; Fatty Acids; Female; Health Status; Humans; Immunity; Lipid Peroxidation; Lipids; Macula Lutea; Male; Middle Aged; Patient Compliance; Placebos; Risk Factors; Sucrose; Xanthophylls; Zeaxanthins

Topics: beta Carotene; Eye Diseases; Fatty Acids, Omega-3; Humans; Lutein; Macular Degeneration; Zeaxanthins; Zinc

To evaluate the association between serum carotenoids and quantitative measures of retinal vasculature in elderly Singapore Chinese subjects. The following details were collected in 128 healthy subjects: sociodemographics, lifestyle information, medical and drug history, and anthropometric measurements. Serum concentrations of carotenoids were estimated in fasting venous blood using high performance liquid chromatography. Retinal vascular parameters were quantitatively measured from retinal photographs using a computer-assisted program (Singapore I Vessel Assessment). The mean age of the population was 54.1 years (range 40 to 81 years). In multiple linear regression analysis, per SD decrease in retinal arteriolar caliber [β = 0.045 (0.003 to 0.086), p = 0.036], per SD increase in retinal venular caliber [β = -0.045 (-0.086 to -0.003), p = 0.036] and per SD increase in arteriolar branching angle [β = -0.039 (-0.072 to -0.006), p = 0.021] were associated with decreased serum lutein. Per SD increase in retinal venular tortuosity [β = -0.0075 (-0.0145 to -0.0004), p = 0.039] and per SD increase in arteriolar branching angle (β = -0.0073 [-0.0142 to -0.0059], p = 0.041) were associated with decreased serum zeaxanthin. None of the other carotenoids demonstrated meaningful relationship with quantitative measures of retinal vasculature. Lower levels of lutein and zeaxanthin demonstrated significant relationship with adverse quantitative measures of retinal vasculature in elderly healthy subjects.

Topics: Adult; Aged; Asian People; Blood Pressure; Carotenoids; China; Cross-Sectional Studies; Eye Diseases; Female; Humans; Lutein; Male; Middle Aged; Multivariate Analysis; Regression Analysis; Retina; Retinal Vessels; Singapore; Venules; Zeaxanthins

Light-absorbing and antiradical properties of the new product on a basis of lutein and zeaxanthin for correction of eye diseases in model system of initiated oxidation of isopropylbenzene were investigated. It is shown, that the product is the effective light-absorbing agent and inhibitor of free-radical oxidation in vitro. In experiments on animals (rat) the pharmacokinetics of the product was investigated at single oral administration. A simple, specific and sensitive RP-HPLC method for the determination of lutein in rat plasma was developed, which was applied to pharmacokinetic investigation in rats after oral administration of lutein at dose 20 mg/kg. It was established, that the peak plasma levels was achieved to 2 hour and the mean elimination half life was 2,4 hours.

Topics: Administration, Oral; Animals; Antioxidants; Chromatography, High Pressure Liquid; Disease Models, Animal; Eye Diseases; Free Radicals; Lutein; Oxidation-Reduction; Rats; Rats, Wistar; Spectrophotometry; Xanthophylls; Zeaxanthins

Ophthalmologists have to deal with the prescription of commercial preparations containing essential nutrients and/or phytonutrients with antioxidant or other properties that are presented as able to protect the eyes against several degenerative diseases. This kind of preparation has to be in conformity with the Belgian Legislation on food and food products that mentions the nature and the quantity of active components they are allowed to contain. Nevertheless, they cannot mention allegations related to health or to the treatment of diseases. Carotenoids such as lutein, zeaxanthin or lycopene are not covered by this Legislation as they are not pro-vitamin A. Therefore, they have to be considered as potentially harmful according to the Belgian Legislation dated March 3, 1992. Finally, their long-term toxicity has never been documented and no dietary recommendations exist as far as they are concerned. On the contrary, several warnings have been published about their chronic intake at supranutritional doses. Even if a complementary administration of these carotenoids is in some way meaningful, it is a pity that their commercial use has preceded the scientific data that remain necessary to collect about them. It seems preferable to advise "dietary" alternatives and avoid the use of unbalanced food complements.

Topics: Animals; Belgium; Carotenoids; Dietary Supplements; Eye Diseases; Humans; Legislation, Drug; Lycopene; Xanthophylls; Zeaxanthins