Bilberry berries and leaves are used for herbal medicines. The berries contain compounds called anthocyanosides, which are known to strengthen blood vessels and improve circulation, and can be useful in treating eye disorders, such as diabetic retinopathy, cataracts, and glaucoma, and circulation disorders, such as varicose veins and hemorrhoids. These same compounds also strengthen the retina, the part of the eye that controls night vision and helps the eye adapt to light changes. During World War II, British fighter pilots ate bilberries before going on nightly bombing raids because their night vision improved as a result.

Bilberry leaves have been used to control blood sugar levels in people with diabetes, but there is no documented evidence of how successful this treatment is. While bilberries are safe in any amount, bilberry leaves taken in large amounts over a long period of time can become toxic, and limited use is recommended.

Dried bilberries have been used for many years to treat diarrhea. The dried berry is high in tannin, which helps control and reduce the intestinal inflammation that can cause diarrhea.

Bilberry extract can also help protect the stomach against ulcers. It stimulates production of stomach mucus, which protects against digestive acids. And because it relaxes muscles, it can help relieve menstrual cramps.

Bilberry is a shrub that grows to about 16 inches high. It has oval, pointed leaves and small pink and white flowers, which bloom from April through June. In the late summer, its dark purple berries are ripe to pick. Bilberry is a botanical relative of blueberry, cranberry, and huckleberry, and its fruit looks and tastes much like the American blueberry. The fruit can be eaten fresh or dried, or used in jams and preserves.

The most important compounds in bilberry fruit and extract are the anthocyanosides. These compounds help build stronger capillaries and improve circulation to all areas of the body. They also reduce the stickiness of blood platelets, keeping them from causing blood clots. These compounds also help increase production of rhodopsin, a pigment that improves night vision and helps the eye adapt to light changes. Bilberry leaves are high in chromium, which may be why they seem to help control blood sugar levels in people with diabetes. Dried bilberries are high in tannin and pectin, which have an astringent action that controls the inflammation that causes diarrhea.

Bilberries may be eaten fresh or dried. Bilberry tea may also be made from fresh or dried berries, or from the leaves. Bilberry extract comes powdered as capsules and should be standardized to 25% anthocyanidins. The extract contains the highest percentage of anthocyanidins, making it the most effective form of bilberry.

• For eye conditions and circulation: standardized bilberry extract (with 25% anthocyanidin) in encapsulated form, dosage of 480 mg a day in two to three divided doses. After improvement, maintenance dosage of 240 mg daily. Maintenance dosage used for prevention.
• For menstrual cramps and ulcer prevention: 20 to 40 mg bilberry extract three times a day, 2 to 4 ml tincture (1:5) three times a day, or one half cup of fresh bilberries.
• For diarrhea: 5 to 10 crushed dried bilberries in cold water, brought to a boil for 10 minutes, then strained.
• For diabetes: Pour boiling water over 1 g (approximately 1½ tsp) bilberry leaf and strain after 10 to 15 minutes. Use long-term only under the supervision of your health care provider.

Bilberry fruit and extract are safe, with no known side effects. They are considered safe for use during pregnancy and nursing. Bilberry leaf is safe with appropriate usage, but should not be taken in large quantities over an extended period of time because it may become toxic.

No noteworthy interactions (positive or negative) between bilberry and conventional medications are known to have been reported in the literature to date.

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