Q. My eye doctor suggested I take bilberry. Will it cause any complications for my diabetes?
A. Bilberry, an herb related to blueberry, is rich in antioxidants called anthocyanins that give the berries their deep purple color. Bilberry was traditionally used as a diabetes treatment before modern pharmaceuticals were available. Animal research indicates that it can help reduce high blood sugar and insulin hyper-response (Journal of Nutrition, March, 2010), so we encourage you to monitor your blood sugar carefully. A study in Finland showed that a diet rich in fatty fish, bilberries and whole grain products could reduce blood lipids as well as blood sugar and inflammation among people with type 2 diabetes (Diabetologia, Nov., 2011).
Preliminary studies suggest that bilberry extract may help prevent eye damage associated with diabetes. Much of this research was conducted in animals; bilberry appears to protect neurons involved in retinal degeneration (Molecular Nutrition & Food Research, Jul. 2009) and protect the retina from stress-induced changes in gene expression (Molecular Vision, 2012).
No serious side effects of bilberries have been reported. One study from Japan shows that bilberry extract may have the potential to interact with intestinal enzymes critical for drug absorption (Drug Metabolism & Disposition, Apr. 2006). As a result, you may want to take it at a different time from your medications.