High levels of vitamin D appear to lower risk of age-related macular degeneration in young women

"Age-related macular degeneration (AMD), a chronic, late-onset disease that results in degeneration of the macula, is the leading cause of adult irreversible vision loss in developed countries," the authors write as background information in the article. "Age-related macular degeneration affects approximately 9 percent (8.5 million) of Americans aged 40 years and older."

Amy E. Millen, Ph.D., of the School of Public Health and Health Professions, University at Buffalo, New York, and colleagues examined data from 1,313 women to investigate if serum 25(OH)D levels in the blood was associated with early age-related macular degeneration. "Serum 25(OH)D is the preferred biomarker for vitamin D status, as it reflects vitamin D exposure from both oral sources and sunlight." Women were participants of the Carotenoids in Age-Related Eye Disease Study, an ancillary study within the Women's Health Initiative Observational Study.

After adjusting for age and other known risk factors for AMD, no significant relationship was found between vitamin D status and early or advanced AMD. In women younger than 75 years (n=968), higher levels of serum 25(OH)D was associated with a significant decreased risk of early AMD, however in women 75 years and older (n=319), higher levels were associated with a borderline statistically significant increased risk.

In women younger than 75 years, intake of vitamin D from foods and supplements was associated with decreased risk of developing early AMD. Women who consumed the most vitamin D had a 59 percent decreased odds of developing early AMD compared with women who consumed the least vitamin D. The top food sources of vitamin D in the sample were milk, fish, fortified margarine and fortified cereal. No relationship was observed using self-reported time spent in direct sunlight.

"This is the second study to present an association between AMD status and 25(OH)D, and our data support the previous observation that vitamin D status may potentially protect against development of AMD," the authors conclude. "More studies are needed to verify this association prospectively as well as to better understand the potential interaction between vitamin D status and genetic and lifestyle factors with respect to risk of early AMD."