Macular pigment is principally comprised of the retinal carotenoids zeaxanthin (Z) and lutein (L) which are derived through dietary intake (1,2). Macular pigment is believed to protect the retina from ultraviolet light. The protective effect is due to anti-oxidative activity. While there is a great deal of inter-patient variability in macular pigment density, it has been found that the pattern of retinal distribution of macular pigment correlates with the spatial profile of retinal pathology in patients with AMD; i.e. retinal changes are greatest where pigment is least dense. It is believed that AMD may develop due to cumulative oxidative damage in the aging eye. This etiology is consistent with epidemiological findings identifying the risk factors for AMD: age, smoking, increased sunlight exposure, low ocular melanin, light colored iris, family history, and female sex (1). Family history and gender, as risk factors, may be related in part to their effect on the macular pigment density. While the etiology of AMD is complex, there is evidence that increasing macular pigment density (through increased intake of lutein and zeaxanthin) may decrease the risk of AMD.

Dietary intake of Lutein and Zeaxanthin: Effect on macular pigment density
 

Researchers Hammond, Johnson, Russell and colleagues performed a study in which they measured macular pigment in 13 patients who received dietary modification for a period of up to 15 weeks (2). Subjects were given daily servings of spinach and corn, which added 11.2-mg lutein and 0.6 mg zeaxanthin. Relative to an average diet, this increased L intake 4-fold and Z intake 3-fold. Eight of 10 patients compliant on the spinach/corn supplement diet exhibited an average increase in macular pigment density of 19% (minimum of 13%).

Lutein and Zeaxanthin: Effect of dietary intake and serum levels on Risk of AMD
 

Investigators in the large NEI-funded Eye Disease Case-Control Study reported in 1993 that among the 1000-plus participants, those with serum levels of lutein and zeaxanthin at the 80th percentile had a 70% decreased risk of AMD (3). Those at the 20-80th percentile in serum levels experienced a 50-60% decrease in risk relative to those below the 20th percentile. Furthermore, increasing serum levels correlated linearly with a progressive decrease in risk of AMD. Seddon and colleagues studied over 300 patients and reported a 57% decrease in risk of AMD in patients with increased dietary intake of lutein and zeaxanthin (4).

These studies, which will be summarized in greater detail in future EduFacts, provide strong presumptive evidence of the value of increased dietary intake of lutein and zeaxanthin to maintain the macular pigment density and to protect macular health.

References

1. Snodderly DM, Evidence for protection against age-related macular degeneration by carotenoids and antioxidant vitamins. Am J Clin Nutr. 1995; 62(suppl): 1448s-1461s.
2. Hammond BR, Johnson EJ, Russell RM, et al. Dietary Modification of Human Macular Pigment Density. Invest Ophthalmol Vis Sci. 1997; 38(9): 1795-1801.
3. Eye Disease Case Control Study Group. Antioxidant Status and Neovascular Age-Related Macular Degeneration. Arch Ophthalmol. 1993; 111:104-109.
4. Seddon JM, Ajani UA, Sperduto RD et al. Dietary Carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. JAMA 1994; 272: 1413-1420.