Herbs & Supplements

Should I take it?

Closely related to blueberries, bilberries are believed to be native to Northeastern Europe. A small perennial bush, bilberry bears white or pinkish flowers late in the spring. The leaves are quite attractive--during the growing season they are a light green or green-yellow that becomes a reddish color in the autumn. Both the flowers and the leaves are waxy in appearance. Numerous wrinkled, dark blue or black berries that resemble blueberries in size and shape ripen in the autumn. Although they are cultivated as a crop in some countries of Eastern Europe, most bilberries grow wild in damp woodlands and marsh edges. In Britain and Europe, the bushes are often used in landscaping.

Like other berries, bilberry fruits are harvested and used for cooking, baking, and making jams. Dried bilberries are used like raisins. They have a slightly sour taste more similar to cranberries than blueberries. In earlier times, bilberries were added to wine to give it color. They were also used to prevent scurvy, a condition caused by vitamin C deficiency. Both the fruits and, less frequently, the leaves of bilberry are used in medicine. Ripe bilberries are collected and dried; bilberry leaves are harvested and dried before they begin to color in the fall.

Dosage and Administration

Bilberry is available in commercial oral dosage forms such as capsules, extracts, and tablets. It is often sold in combination with other herbals such as eyebright or supplements such as beta-carotene that also may enhance vision. Each of these products has various strengths and different recommendations for dosing. Individuals who decide to use one of them should follow the directions on the package that is bought.

A tea may be made from either dried bilberries or dried bilberry leaves. No limits are suggested for the maximum amount of tea per day, but continual use for more than a few days at a time is discouraged because of the tannin content.

• To make bilberry fruit tea about 2 teaspoons of dried bilberries should be allowed to soften for several minutes or longer in about 5 ounces of cold water. The water should then be heated but not boiled for about 10 minutes. The bilberries should be removed before drinking the tea, but they may be eaten or used in cooking, if desired.
• For bilberry leaf tea, 2 teaspoons of chopped dried bilberry leaf should be soaked in 5 ounces to 8 ounces of boiling water for 10 minutes. The solid particles should be strained out before drinking the tea.

Summary

Bilberries may be taken by mouth to treat retinopathy, chronic venous insufficiency, hemorrhoids, and other conditions that are associated with the deterioration of small blood vessels. They may also help to relieve diarrhea and sore throats. Leaves from the bilberry bush may also have some medicinal effects, but they have not been studied as much as the possible effects of the berries.

Risks

Bilberry contains varying amounts of chemicals known as tannins, which have been associated with kidney or liver damage. While eating small amounts of bilberries as part of the diet appears to be safe, consuming large amounts or continually taking supplemental bilberry should be avoided by pregnant women and individuals with diabetes.

Side Effects

Other oral products that contain high percentages of tannins may contribute to esophageal or mouth cancer. Kidney and liver damage may also result from continued use or high doses of oral products with high tannin contents. No reports of side effects have been documented from bilberry, however.

Interactions

Bilberry potentially may interfere with the effectiveness of insulin, oral drugs for diabetes, and herbal products that affect blood sugar levels. It may also block the absorption of some drugs and nutrients.

Last Revised July 15, 2008