Bilberries are closely related to the North American blueberry and huckleberry and are in the same genus Vaccinium. These purple-blue berries get their pigmentation from compounds called anthocyanins, which have demonstrated potent antioxidant and anti-inflammatory properties.
Considerable attention and research has focused on the health benefits of bilberry fruits, and the following is an overview of recent findings. Many of these studies employed mouse models because they are the most commonly used vertebrate species for health research, and are widely considered to be the prime model of inherited human disease and share 99% of their genes with humans. Human clinical studies typically follow once such animal studies produce strong evidence.
In one study, researchers tested the effect of dietary bilberry extracts on hyperglycemia (high blood sugar) and insulin sensitivity in type 2 diabetic mice. They found that dietary bilberry extract supplementation significantly reduced blood glucose concentrations and enhanced insulin sensitivity in these mice. The authors suggest the findings provide a biochemical basis for the use of bilberry fruits, and have important implications for the prevention and treatment of type 2 diabetes.
Bilberry has been considered effective in helping boost circulation to the eyes, providing needed nutrients that protect eyes from eyestrain and fatigue.
In another mouse study, oral administration of bilberry extract showed protective effects against uveitis [inflammation of the uvea, the vascular layer of the eye sandwiched between the retina and the white of the eye (sclera)] by decreasing endogenous free radical compounds and increasing endogenous antioxidant compounds, and the effects of the bilberry extract were dose-dependent. The authorís results provide new evidence to help elucidate the beneficial effects of bilberry extract on eye health.
Inflammation and Cardiovascular Disease
The various and abundant polyphenols found in bilberries as well as several other plant foods have been associated with the ability to prevent and treat chronic inflammatory diseases.
In a human study, investigators looked at the effect of bilberry juice on serum and plasma biomarkers of inflammation and antioxidant status in subjects with elevated levels of at least one risk factor for cardiovascular disease. This was a randomized controlled trial where participants consumed either bilberry juice or water. Supplementation with the bilberry juice resulted in significant decreases in plasma concentrations of pro-inflammatory proteins that are crucial in orchestrating inflammatory responses. Plasma levels of polyphenols from bilberry, specifically quercetin and p-coumaric acid, were increased in the bilberry group. The authors suggest that supplementation with bilberry polyphenols may modulate inflammation processes, and recommend further testing of bilberry supplementation as a potential strategy in the prevention and treatment of chronic inflammatory diseases.
Pruritus (Itchy Skin)
Researchers examined whether bilberry extract would alleviate pruritus in a mouse model of chronic allergic contact dermatitis. Oral treatment with bilberry extract significantly attenuated scratching behavior, and the authors propose that anthocyanins from bilberry might be beneficial for the treatment of chronic pruritus, which can occur in patients with inflammatory skin diseases such as atopic dermatitis.
Obesity and Metabolic Syndrome
Another study examined the effects of anthocyanidin-enriched bilberry extracts on adipocyte (fat cell) differentiation. Treating the cells with bilberry extract strongly inhibited adipocyte differentiation via an insulin pathway. The authors propose bilberry extracts might be used as a potential complementary treatment for obese patients with metabolic syndrome - a cluster of conditions such as increased blood pressure, high blood sugar level, excess body fat around the waist, or abnormal cholesterol levels that occur together, and increase risk of heart disease, stroke, and diabetes.
Bilberries are one of the richest sources of dietary anthocyanins. Given the already documented effects of these compounds and ongoing interest by scientists to discover and define roles for an array of health conditions, the potential expansion for use of bilberry extracts, and similar polyphenol-type plant extracts, is very strong.