(FT. LAUDERDALE, Fla., May 9, 1999) - Dietary lutein and zeaxanthin are the major determinants to explain macular pigment optical density (MPOD), according to research presented today at the Association for Research in Vision and Ophthalmology 1999 annual meeting. The study was the largest ever conducted to examine the relationship between dietary, medical, physical and lifestyle factors, and macular pigment density, thought to be protective in age-related macular degeneration (AMD).
"Results confirmed and expanded upon what's already known about the determinants of macular pigment density. Dietary lutein and zeaxanthin explained the greatest amount of macular pigment density variance, followed by serum lutein levels," said Thomas Ciulla, M.D., Retinal Specialist, Indiana University School of Medicine and Ophthalmology Department in Indianapolis, Ind.
Ciulla and his colleagues examined the MPOD of a cross sectional population of 280 healthy men and women in Indianapolis. They determined that dietary lutein and zeaxanthin, serum lutein and eye color are the factors most strongly associated with macular pigment density. Ciulla cautions, however, that, taken together, these factors explained only 19.7 % variance in MPOD.
Lutein and zeaxanthin are concentrated in retinal macular pigment and accumulation is thought to be dependent on dietary intake. Macular pigment may filter blue light that damages photoreceptors and the retinal pigment epithelium. In addition, carotenoids may limit oxidant stress resulting from metabolism and light, acting as antioxidants.
In this study, serum concentrations for lutein, zeaxanthin and beta-carotene were measured by HPLC, and MPOD was measured by heterochromatic flicker photometry. Dietary patterns and demographic/medical characteristics were determined by questionnaire. This method of study was a non-invasive way to measure MPOD and also showed that MPOD can be reliably measured in a cross sectional research study.
Ciulla said additional research is needed to more fully assess the role of lutein and other macular carotenoid pigments in AMD. Lutein and zeaxanthin are found in dark leafy green vegetables like spinach and kale.
Higher intake of lutein and zeaxanthin from the diet may play a role in reducing the risk of age-related macular degeneration (ARMD), the leading cause of blindness in people over age 65 in the United States, but further research is necessary.