A recent study suggests that low vitamin D levels may be linked to age-related macular degeneration (AMD), the leading cause of vision loss in older adults.
The researchers analyzed data from 1,313 postmenopausal women who participated in the Carotenoids in Age-Related Eye Disease Study. A total of 241 were diagnosed with early AMD.
The authors found that women younger than 75 who had less than 38 nanomoles of vitamin D per liter of blood were more likely to develop AMD than women who had higher levels of vitamin D. Women with higher blood concentrations of vitamin D were about 44 percent less likely to develop AMD.
The Adequate Intake (AI) levels for all individuals younger than age 50 is 5 micrograms daily. For adults age 50-70, 10 micrograms is recommended. For individuals older than 70, 15 micrograms is recommended. Some authors have questioned whether the current recommended AI levels are sufficient to meet physiological needs, particularly for those deprived of regular sun exposure. The upper limit for vitamin D has been recommended as 2,000 international units daily due to toxicities that can occur when taken in higher doses.
Millen AE, Voland R, Sondel SA, et al. Vitamin D Status and Early Age-Related Macular Degeneration in Postmenopausal Women. Arch Ophthalmol. 2011 Apr;129(4):481-489.
Natural Standard: The Authority on Integrative Medicine. www.naturalstandard.com