In Western countries, degeneration of the macula, the center of the eye’s retina, is a leading cause of blindness in older adults. Long-term blue light exposure and oxidative damage in the outer segments of photoreceptors may lead to drusen and/or pigment abnormalities in the macula, increasing the risk of age-related macular degeneration (AMD) and central blindness.
Dietary lutein and zeaxanthin: The carotenoids found in the retina are lutein and zeaxanthin, which are both of dietary origin, and meso-zeaxanthin, which is derived from lutein. These three carotenoids are present in high concentrations in the macula (known as macular pigment), where they are efficient absorbers of blue light. They may prevent a substantial amount of the blue light entering the eye from reaching the underlying structures involved in vision and protect against light-induced oxidative damage, which is thought to play a role in the pathology of age-related macular degeneration (reviewed in 19). It is also possible, though not proven, that lutein, zeaxanthin, and meso-zeaxanthin, act directly to neutralize oxidants formed in the retina.
Increasing dietary consumption of lutein and zeaxanthin was shown to raise their serum concentration and macular pigment density (61, 62). Some, but not all, observational studies have provided evidence that higher intakes of lutein and zeaxanthin are associated with lower risk of age-related macular degeneration (AMD) (63). While cross-sectional and retrospective case-control studies found that higher levels of lutein and zeaxanthin in the diet (64-66), blood (67, 68), and retina (69, 70) were associated with a lower incidence of AMD, several prospective cohort studies found no relationship between baseline dietary intakes or serum concentrations of lutein and zeaxanthin and the risk of developing AMD over time (71-74). A recent report examined the association between the incidence of AMD and calculated dietary intakes and predicted plasma concentrations of lutein and zeaxanthin in older adults (≥50 years) from two large prospective cohorts, the Nurses’ Health Study (NHS; 63,443 women) and the Health Professionals Follow-up Study (HPFS; 38,603 men), followed for 26 years and 24 years, respectively (75). The highest versus lowest quintile of predicted plasma lutein and zeaxanthin scores was associated with a 41% lower risk of advanced AMD, yet no association was found with intermediate AMD. The evidence also suggested that the consumption of about 6 mg/day of lutein and zeaxanthin from fruit and vegetables (compared with less than 2 mg/day) may decrease the risk of advanced AMD (75).