SAN FRANCISCO—In theory, vitamins C and E, and magnesium could help prevent or limit diabetic retinopathy (DR), a potentially blinding disease, since each nutrient causes the body to respond in ways that alter retinopathy mechanisms. In this month’s Ophthalmology, the journal of the American Academy of Ophthalmology, a research review reported on the effects of vitamins C and E, and magnesium on DR.
A research team led by Amanda Adler, M.D., Ph.D., Institute of Metabolic Science, Cambridge, United Kingdom, surveyed studies published from 1988 through 2008 on the impact of these micronutrients on DR. Based on 15 selected studies comprising 4,094 individuals, Adler said the evidence is not strong enough yet to recommend vitamins C or E, or magnesium supplements for patients with diabetes. She thinks the research should continue, though, and recommends specific parameters.
“It is a very attractive proposition that what one eats, rather than a medication, might reduce the risk of diabetic complications,” she said. “Ideally, future studies would include frequent measurement of intake of these three nutrients through diet and supplements, standardized exams to identify DR, and agreed-upon biomarkers to assess DR progression. If such studies showed apparent protection against DR, then a randomized clinical trial could determine more precisely how a person with diabetes might, or might not, alter his intake of any of these nutrients.”
The survey found in hospital-based studies, participants with higher levels of vitamin C in their blood were less likely to have DR, but in population-based studies there was no association between dietary intake of vitamin C and DR. For vitamin E, no studies showed an association between blood levels or dietary intake and DR risk. For magnesium, one study showed an association between low blood levels of magnesium and DR progression, but other studies were inconclusive.
