Health Aspects of Bilberry
Both the leaves and the ripe fruit of the bilberry and related berry species have long been a folk remedy for treating diabetes. While the leaves can lower blood sugar, they do so by impairing a normal process in the liver. For this reason, use of the leaves is not recommended for long-term treatment.
The berry, on the other hand, is recommended for people with diabetes. The berries do not lower blood sugar, but their constituents may help improve the strength and integrity of blood vessels and reduce damage to these vessels associated with diabetes and other diseases, such as atherosclerosis (calcium and fat deposits in arteries). The berries contain flavonoids, compounds found in the pigment of many plants. The blue-purple pigments typical of this family are due to the flavonoid anthocyanin.
With their potent antioxidant activity anthocyanins protect body tissues, particularly blood vessels, from oxidizing agents circulating in the blood. In fact, bilberries contain the highest antioxidant level, bite for bite, of any berry! Two common complications of diabetes, diabetic eye disease (retinopathy) and kidney disease (nephropathy), often begin when the tiny capillaries of these organs are injured by the presence of excessive sugar. Antioxidants allow these harmful oxidizing agents to bind to them instead of to body cells, preventing the agents from causing permanent damage to the lining of blood vessels.
Bilberry extracts also may reduce the tingling sensations in the extremities associated with diabetes. Several studies have shown that bilberry extracts stimulate blood vessels to release a substance that helps dilate (expand) veins and arteries. Bilberries help keep platelets from clumping together, which, in turn, thins the blood, prevents clotting, and improves circulation.
Bilberry preparations seem particularly useful in treating eye conditions, so in addition to diabetic retinopathy, they also are used to treat cataracts, night blindness, and degeneration of the macula, the spot in the back of the eye that enables sharp focusing.
* Cancer prevention
* Circulatory disorders
* Diabetic retinopathy
* Macular degeneration
* Varicose veins
* Visual acuity
Uses based on scientific evidence
Atherosclerosis ("hardening" of the arteries), peripheral vascular disease. Bilberry has sometimes been used traditionally to treat heart disease and atherosclerosis. There is some laboratory research in this area.
Cataracts. Bilberry extract has been used for a number of eye problems, including the prevention of cataract worsening. At this time, there is limited scientific information in this area.
Chronic venous insufficiency. Chronic venous insufficiency is a condition that is more commonly diagnosed in Europe than in the United States, and it may include leg swelling, varicose veins, leg pain, itching, and skin ulcers. A standardized extract of bilberry called Vaccinium Myrtillius Anthocyanoside (VMA) is popular in Europe for the treatment chronic venous insufficiency. However, there is only preliminary research in this area, and more studies are needed.
Diabetes mellitus. Bilberry has been used traditionally in the treatment of diabetes. Scientific Human research is needed in this area
Diarrhea. Bilberry is used traditionally to treat diarrhea, but there is a lack of reliable research in this area.
Fibrocystic breast disease. There is limited research suggesting a possible benefit of bilberry in the treatment of fibrocystic disease of the breast.
Painful menstruation (dysmenorrhea). Preliminary evidence suggests that bilberry may be helpful for the relief of menstrual pain.
Retinopathy. Based on animal research and several small human studies, bilberry may be useful in the treatment of retinopathy in patients with diabetes or high blood pressure. However, this research is still in its early stages.
Stomach ulcers (peptic ulcer disease). Bilberry extract has been suggested as a treatment to help stomach ulcer healing. There is some support for this use from laboratory and animal studies.
Night vision. Traditional use and several unclear studies from the 1960s and 1970s suggest possible benefits of bilberry on night vision. However, more recent well-designed studies report no benefits.
Uses based on tradition or theory
The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Age-related macular degeneration, angina (chest pain), angiogenesis (blood vessel formation), antifungal, antimicrobial, antioxidant, antiseptic, antiviral, arthritis, bleeding gums, burns, cancer, cardiovascular disease, chemoprotectant, chronic fatigue syndrome, common cold, cough, dermatitis, dysentery (severe diarrhea), edema (swelling), encephalitis (tick-borne), eye disorders, fevers, glaucoma, gout (painful inflammation), heart disease, hematuria (blood in the urine), hemorrhoids, high blood pressure, high cholesterol, kidney disease, lactation suppression, laxative (fresh berries), leukemia, liver disease, macular degeneration, oral ulcers, pharyngitis, poor circulation, retinitis pigmentosa, scurvy, skin infections, sore throat, stomach upset, tonic, urine blood, urinary tract infection, varicose veins of pregnancy, vision improvement.
Mechanism of Action
The anthocyanins in bilberry contribute to most of its pharmacological activities (see references below). Anthocyanin has anti-inflammatory, vasoprotective (12), and antioxidant effects (13). It has demonstrated free radical scavenging and inhibition of cAMP phosphodiesterase actions. Extract of bilberry can inhibit human leukemia cells and human colon carcinoma cells growth through the induction of apoptosis (natural cell death) (10). In vitro and in vivo clinical studies show inhibition of platelet aggregation and stimulation of vascular prostacyclin. Bilberry anthocyanins regenerate rhodopsin and are indicated in treatment of poor night vision, mascular degeneration, glaucoma and cataracts(2) (3) (4)
Numerous human studies have shown that bilberry in standardized extract form of 25% anthocyanosides is effective in preventing diabetic retinopathy and improving visual acuity and retinal function.
Several human (see references below) studies suggest that bilberry anthocyanosides prevent diabetic retinopathy and improve visual acuity and retinal function (6, 7, 8, 9). In vitro studies suggest bilberry has anticancer activities (10, 11, 14). Products should be standardized to 25% anthocyanosides. Coumarins present in bilberry may interact with platelets and have an additive effect with blood thinners (5). No adverse reactions have been reported. (Note: Bilberry fruit should not be confused with bilberry leaf, which may cause hypoglycemia).
Side Effects and Warnings
Bilberry is generally believed to be safe in recommended doses, based on its history as a foodstuff. There is a lack of known reports of serious toxicity or side effects, although if taken in large doses, there is an increased risk of bleeding, upset stomach, or hydroquinone poisoning.
Based on human use, bilberry fresh fruit may cause diarrhea or have a laxative effect. Based on animal studies, bilberry may cause low blood sugar levels. Caution is therefore advised in patients with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Serum glucose levels may need to be monitored by a healthcare provider and medication adjustments may be necessary.
In theory, bilberry may decrease blood pressure, based on laboratory studies.Experts have warned that patients should use dried bilberry preparations because the fresh fruit may actually worsen diarrhea.
Interactions with Drugs
Bilberry may lower blood sugar levels, although there is a lack of reliable human studies in this area. Caution is advised when using medications that may also lower blood sugar, because of the additive effect. Patients taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare provider. Medication adjustments may be necessary.
Based on human use, when taken with drugs that cause or worsen diarrhea, such as laxatives or some antibiotics, bilberry may increase diarrhea because of the additive effect. There are no reliable published human reports of bleeding with the use of bilberry. However, when taken with drugs that increase the risk of bleeding, Bilberry theoretically may increase the risk of bleeding because of the additive effect. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®). Based on theory, when taken with drugs that decrease blood pressure bilberry may further lower blood pressure because of the additive effect.
Based on early laboratory study, berry extracts have been shown to inhibit H. pylori , an ulcer-producing bacteria and enhance the effects of the prescription drug clarithromycin (Biaxin ®).
Bilberry may also interact with anticancer agents, liver-damaging agents, and estrogen-containing medications. Consult with a qualified healthcare professional, including a pharmacist, to check for interactions.
Interactions with Herbs and Dietary Supplements
Based on animal research, bilberry may lower blood sugar levels. Use of the Bilberry is appropriate with insulin-dependent diabetes because it does not interfere with diabetes medications, and can help prevent some complications of diabetes. (Note: caution is advised when using herbs or supplements that may also lower blood sugar, although there is a lack of reliable human study in this area. Blood glucose levels may require monitoring, and doses may need adjustment to ensure safety).
Based on theory, when taken with herbs or supplements that decrease blood pressure, bilberry may further lower blood pressure .
Based on theory, when taken with herbs and supplements that are believed to increase the risk of bleeding, bilberry may increase the risk of bleeding because of the additive effect. Multiple cases of bleeding have been reported with the use of Ginkgo biloba and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.
Based on traditional use, when taken with herbs and supplements that are also believed to have laxative effects, bilberry may increase diarrhea or laxative effects because of the additive effect.
Bilberry contains resveratrol, which has been studied as an antioxidant, for cardiovascular disease, and for cancer and may have additive effects when taken with supplements like grape seed.
Bilberry may also interact with anticancer agents, antioxidants, liver-damaging agents, and herbs or supplement with hormonal properties. Consult with a qualified healthcare professional, including a pharmacist, to check for interactions.
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