What Is Bilberry?

Bilberry is a fruit closely related to blueberry. It is native to northern Europe, Asia, the northern United States, and Canada. Its uses for health purposes dates back to the Middle Ages.

Also known as European blueberry, bilberry is often eaten fresh or made into jam, juices, or pies. Bilberry is also available in powder, juice, or supplement form.

Historically, bilberry has been used to treat diabetes, inflammation, and diarrhea. Today, bilberry supplements are marketed for numerous conditions, including eye health, inflammatory bowel disease (IBD), and heart disease. However, there is not enough research to support bilberry's use for any health condition.

This article reviews the research on bilberry, its side effects, interactions, and more.

Uses of Bilberry

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian, pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease.

Bilberry contains antioxidants known as anthocyanins and polyphenols. These antioxidants are thought to curb inflammation and protect against diseases associated with oxidative stress.

So far, very few studies have tested the health effects of bilberry, and most have had mixed results or produced limited evidence. There is not enough research to recommend bilberry's use for treating any health condition.

Some of bilberry's purported uses include:

Eye Health

Bilberry is often touted as a remedy for certain eye conditions. These include:

• Glaucoma (a condition caused by pressure in the eye)
• Cataracts (clouding of the lens of the eye)
• Dry eyes
• Age-related macular degeneration (loss of vision due to aging)
• Retinitis pigmentosa (a rare disease of the light-sensitive area of the eye)
• Eye fatigue
• Night vision

So far, there isn't much scientific evidence to support most of these uses for bilberry.

There has been some preliminary research into bilberry supplementation for preventing eye fatigue. A small 2015 study in video display terminal workers found that those who took a dietary supplement containing bilberry extract experienced a reduction in subjective eye fatigue symptoms compared to a placebo.

A more recent study found that 240 milligrams (mg) of bilberry extract given for 12 weeks helped relieve symptoms of eye fatigue associated with high use of visual display terminals.

Bilberry supplements have long been believed to improve night vision, but the research does not support that theory. There is little to no research on other aspects of eye health and bilberry use.

This research is preliminary, and further studies are needed before determining if bilberry can improve eye health.

Inflammatory Bowel Disease (IBD)

Bilberry contains anthocyanins, which are believed to act against oxidative stress in the body. A few small studies have found that anthocyanins help reduce inflammation in the colon by reducing inflammatory cytokines, proteins that promote inflammation in your body. 

A small 2013 study found that people with mild to moderate ulcerative colitis who took a daily preparation of dried bilberries and concentrated bilberry juice for six weeks showed improvement in symptoms. Sixty-three percent achieved remission. However, it's important to note that this study only included 13 people and did not include a placebo group.

Heart Disease and Metabolic Syndrome

There is not enough evidence to say whether or not bilberry can prevent heart disease. A few small studies have shown that it may reduce cholesterol levels and inflammatory markers, such as C-reactive protein (CRP). Other studies have found that bilberry did not affect weight, cholesterol levels, or blood pressure.

A 2020 review of studies concluded that bilberry extract supplementation and/or consumption of fresh bilberries may reduce cholesterol levels, blood glucose, and insulin levels. It also concluded that bilberries might reduce inflammation in people with metabolic syndrome.

Still, the authors cautioned that many of these studies were done in the laboratory or on animals; they might not translate to humans; and much larger studies need to be done before bilberry can be recommended for treating and preventing these conditions.

Talk to your healthcare provider if you are at risk of developing heart disease.

Gigivitis

Some preliminary research indicates bilberry might help control gum (gingival) inflammation in people with gingivitis.

A study published in the International Journal of Molecular Sciences randomized participants to take either 250 grams (g) of bilberries, 500 g of bilberries, or a placebo, or receive standard care for seven days. The researchers concluded that 500 g of bilberries resulted in a reduction of gum inflammation.

However, further research is needed to determine if bilberry is an appropriate treatment for gingivitis.

Venous Disorders

Varicose veins are twisted, enlarged veins caused by weakened vein walls and valves. Bilberry has long been used to treat this condition and other conditions of the veins, including:

• Chronic venous insufficiency
• Hemorrhoids

Bilberry is believed to protect capillaries, the smallest blood vessels in your body. Still, very little research has been done into bilberry's effectiveness against venous disorders, and more research is needed before its use can be recommended.

Age-Related Cognitive Decline

A few studies have found that dietary supplementation with anthocyanin, the active ingredient in bilberries and related berries, could help improve cognitive performance.   

Similarly, a 2021 review study concluded that the anti-inflammatory and anti-oxidative effects of anthocyanins can help protect against neurodegeneration. An older study in mice also found that supplementation with bilberry and blackcurrant extract might decrease the buildup of beta-amyloid proteins in the brain, which contribute to Alzheimer's disease.

What Are the Side Effects of Bilberry?

Bilberry fruit is generally considered safe when consumed in amounts typically found in food. However, allergic reactions can occur.

Side effects of bilberry supplements can include:

• Nausea or abdominal discomfort
• Low blood sugar levels

If you have diabetes, speak with your healthcare provider before adding bilberry to your regimen.

It's important to remember that supplements aren't routinely tested for safety, adverse reactions are often not reported, and dietary supplements are largely unregulated.

Precautions

Bilberry consumed as food is safe in most instances.

Bilberries naturally contain substances known as tannins (found in many foods such as coffee, tea, red wine, blueberries, cranberries, chocolate, and some nuts and beans). If you have an allergy or sensitivity to foods containing tannins, you should avoid bilberry.

Pregnant or nursing people should avoid bilberry extracts, as safety isn't known.

The safety of long-term use or high doses of bilberry supplements is also uncertain. Consuming bilberry leaves may be unsafe in high amounts or when taken long-term.

If you're considering trying bilberry supplements, talk with your healthcare provider first to weigh the pros and cons and to discuss whether it's appropriate for you.

Dosage: How Much Bilberry Should I Take?

There is not enough scientific data to support a recommended dose of bilberry.

A typical dose of the dried, ripe berries is 20 to 60 g daily. Some consumers also drink a type of bilberry tea.

Bilberry extract in capsule and tablets come in dosage ranges of 40 to 100 mg.

Different amounts have been studied in research. The appropriate dose for you may depend on your age, gender, weight, and medical history. Speak to your healthcare provider to get personalized advice.

What Happens if I Take Too Much Bilberry?

There is not enough data to know the outcome of taking too much bilberry. To be safe, only take the recommended amount as directed on the product packaging. Consult your healthcare provider before consuming bilberry supplements.

Interactions

Anthocyanins may inhibit certain drugs, such as:

• Anticancer medications
• Antibiotics
• Beta-blockers
• Arthritis medication

Bilberry supplements also may thin the blood which, when used in combination with blood thinners (e.g., warfarin), could lead to easily bruising or greater bleeding.

Bilberry supplements may also interact with diabetes medications. Since bilberry may have glucose lowering effects, combining it with medications used to lower glucose levels could lead to hypogylcemia (low blood sugar). Additionally, since bilberry may interfere with blood sugar control, stop taking it two weeks before any planned surgery.

How to Store Bilberry

Follow manufacturer directions for proper storage of supplements. Always store supplements out of reach of children.

Sources of Bilberry and What to Look For

You can find bilberries fresh, frozen, dried, powdered, or in packaged foods like jam. In addition to eating them fresh, you can try adding frozen or powdered bilberries to a smoothie or using them to make a sauce or preserves.

Bilberry supplements and bilberry extract are sold in tablets, capsules, and drops. The berries are also sold dried and as a powder. Bilberry leaves are made into teas.

If you choose to buy a bilberry supplement, the National Institutes of Health (NIH) recommends that you look for a Supplement Facts label on the product that you buy. This label will contain vital information, including the amount of active ingredients per serving and other added ingredients (like fillers, binders, and flavorings).

Make sure the supplement contains the intended berry. Bilberry should be listed on the supplement facts label as Vaccinium myrtillus. Some supplements may have "bilberry" advertised on the front but contain "American bilberry," which is not the same. American bilberry is also known as huckleberry.

Bilberry supplements should also be concentrated and standardized. If possible, look for a supplement with 36% anthocyanosides or 25% anthocyanidins.

Lastly, look for a product with a seal of approval from a third-party organization that provides quality testing. These organizations include USP, ConsumerLab, and NSF. A seal of approval from one of these organizations does not guarantee the product's safety or effectiveness. Still, it does assure that the product was properly manufactured, contains the ingredients listed on the label, and does not contain harmful levels of contaminants.

Summary

Bilberry is a berry native to northern Europe, the northern U.S. states, Asia, and Canada. It can be eaten as a food, and it can be found in supplement form. Bilberry supplements are marketed to help manage several different health conditions. However, there is not enough research evidence to support any of these uses.

While bilberry shouldn't be used as a substitute for standard treatment or preventive measures for any medical condition, in some cases, eating more bilberries (or other anthocyanin-rich fruit) may have some protective benefits.

If you think bilberry would be good for you, talk with your healthcare provider to evaluate the benefits and risks of taking such a supplement.