As lutein and zeaxanthin are present in high concentrations in the center of the eye’s retina (‘macula’), where they are efficient absorbers of blue light, they may protect against light-induced oxidative damage, which is thought to play a role in the pathology of age-related macular degeneration (2). AMD is the leading cause of blindness in older adults, for which there is currently no cure.
While several prospective cohort studies found no relationship between baseline dietary intakes or serum levels of lutein and zeaxanthin and the risk of developing AMD over time (5, 6, 7, 8), epidemiological studies provide some evidence that higher intakes of lutein and zeaxanthin are associated with lower risk of AMD (4). In addition, the Age-Related Eye Disease Study 2 (AREDS2), a 5-year intervention study in 4,203 AMD patients in the age of 50-85 years evaluated a set of variants of the original AREDS formulation, however also including lutein and zeaxanthin. Analyses indicated that administration of 10 mg of lutein along with 2 mg of zeaxanthin yielded a 10% risk reduction in the progression rate of AMD when these xanthophylls were ingested along with the existing AREDS formulation that contained 15 mg of ß-carotene (29). However, when the lutein and zeaxanthin replaced the ß-carotene, a significant 18% reduction in the risk of progression to advanced AMD was found. Furthermore, when the results from the AREDS2 study were evaluated in relation to the dietary intake of the test subjects as reported at the beginning of this study, a significant 26% reduction in risk of progression to advanced AMD was found in subjects ingesting the lowest levels of dietary lutein and zeaxanthin. This is very important since the low dietary intakes of lutein and zeaxanthin among the AREDS2 subjects closely match the typical levels of lutein and zeaxanthin consumed by people around the world.
To date, the available scientific evidence suggests that consuming at least 6 mg/day dietary lutein and zeaxanthin from fruits and vegetables may decrease the risk of age-related macular degeneration (9, 10, 11).
As light absorbers lutein and zeaxanthin may prevent the eye’s lens from ultraviolet light and oxidant damage, causing structural changes that result in the formation of opacities known as cataracts. As people age, cumulative damage to lens proteins often results in cataracts that are large enough to interfere with vision (1).
Several prospective studies found that men and women with the highest intakes of foods rich in lutein and zeaxanthin were 18–50% less likely to require cataract extraction (12, 13) or develop cataracts (14, 15, 16). With other words, serum levels of lutein and zeaxanthin are inversely related to the incidence of cataracts in men and women. This has been confirmed through a meta-analysis of the epidemiological data (32). Furthermore, as part of the AREDS2 study, an analysis of the results for subjects supplemented with lutein and zeaxanthin with the highest dietary intake of lutein and zeaxanthin in comparison to those that did not receive these carotenoids with the lowest intakes showed a significant reduction in the risk of progression to cataract surgery (32% risk reduction), of any cataract (30% risk reduction) or of any severe cataract (36% risk reduction) (31). Similar to the results previously described for AMD, the available data indicate that cataracts may be a nutritionally responsive ocular disorder.
Two human studies suggest that lutein may play a role in atherosclerosis prevention: higher levels of lutein in the blood have been associated with less thickening of arterials walls (17, 33). In addition, intake of green leafy vegetables was associated with a significant reduction of incident ischemic stroke in the Nurse’s Health and Health Professionals Follow-up Study combined (34). More studies are needed to clarify this relationship.
Lung Cancer: Dietary intakes of lutein and zeaxanthin were associated with a decreased lung cancer risk in a six-year study in more than 58,000 Dutch men (3) while other studies did not show such association (see also beta-carotene).
Colon Cancer: In addition, epidemiological analyses from 1993 case subjects with first primary incident adenocarcinoma of the colon and from 2410 population-based control subjects indicated that Lutein was inversely associated with colon cancer in both men and women (35). The greatest inverse association was observed among subjects in whom colon cancer was diagnosed when they were young and among those with tumors located in the proximal segment of the colon.
Breast Cancer: Cohort analysis of 83,234 healthy women who participated in the Nurses' Health Study revealed that intake of lutein and zeaxanthin from food and supplements may reduce the risk of breast cancer in premenopausal women (36). The association was particularly strong among women with a higher risk for breast cancer, as determined by a family history of the disease or alcohol use (defined as at least one alcoholic drink per day). Similarly, another study of 540 women from a cohort in New York found an increased risk of breast cancer in women with very low intakes of lutein due to a poor diet or lack of supplementation (37).
Skin Cancer: A large case-controlled study (a total of 1067 people) investigated the association between diet and melanoma. They reported that high intake of lutein from fruits and vegetables significantly reduces the risk of melanoma (38). The melanoma preventing effect of lutein and zeaxanthin might come from protecting the skin against sun damage (UV radiation) (38).
In general, for all cancer reduction associations by lutein and zeaxanthin, more and larger intervention trials are needed to proof the effects of lutein and zeaxanthin on cancer.
Authored by Dr Peter Engel in 2010, reviewed and revised by Jonas Wittwer on 23.05.2017
