Bilberry Extract and Vision
What the research says about bilberry for vision.
What Is a Bilberry? continued...
David Kiefer, MD, a research fellow in the department of family medicine at the University of Wisconsin in Madison, says it makes sense that bilberries have a reputation for helping conditions ranging from retinopathy (abnormal or damaged blood vessels in the retina) to diarrhea to heart disease.
"A lot of these [conditions] have an inflammatory component, so some herbs treat a variety of things," he says. "There's oxidative damage in so many illnesses. Whether in eye vessels or leg vessels, we can get a positive effect."
Kiefer says patients with macular degeneration -- the deterioration of the central part of the retina that can eventually cause blindness -- have reported that they use bilberry extract, with mild benefit, "but it's hard to sort out the anecdotal report from the placebo effect.''
What Is Bilberry Extract?
Because fresh bilberries are nearly impossible to come by in the U.S., consumers gobble up bilberry extract, one of the top-selling herbal supplements in the U.S., with sales of $28 million in 2010.
The standardized amount of anthocyanosides contained in bilberry extract is 25%. In a bilberry itself, anthocyanidin content ranges from 300 mg to 700 mg per 100 grams of fruit (3.5 ounces), depending on the region where they are picked.
In recent studies of the extract's effects on health, the most compelling evidence is its reduction of retinal inflammation -- although studies have been small and mostly conducted in lab animals.
However, research has not turned up conclusive evidence about bilberry extract's effect on blood glucose levels, or heart or gut health.
Is Bilberry Extract Safe to Take?
Bilberries are safe to eat and to take in extract form, according to the Natural Medicines Comprehensive Database, a compendium of information on herbs and their medicinal properties.
But because anthocyanosides prevent blood platelets from sticking together, bilberry extract may interfere with anticoagulant drugs like warfarin, Kiefer says. "I would use it with caution, due to some of those reports,'' he says.
There is also a question of quality. Foster cautions against buying cheap bilberry extract, which could contain chemicals like dyes. And he advises staying away from bilberry extract that is light in color. That's a tip-off that the content of anthocyanosides may be low.
"It's important to buy from trusted sources," Foster says.