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7 Bilberry Benefits (incl. Eye Health) + Side Effects & Dosage

Written by Carlos Tello, PhD (Molecular Biology) | Last updated:
Puya Yazdi
Medically reviewed by
Puya Yazdi, MD | Written by Carlos Tello, PhD (Molecular Biology) | Last updated:

Bilberry is one of the richest sources of anthocyanins – powerful, bright-colored antioxidants. This European relative of blueberries is fantastic for your eyes. It may also protect your gut and blood vessels, support weight loss, and lower cholesterol. Read on to learn more about its potential benefits and the ways you can use it to improve your health.

What Is Bilberry?

Bilberry (Vaccinium myrtillus) is a small bush with small, dark blue/purple berries. It is also known as European blueberry or whortleberry. The plant is native to forests and mountains of northern and central Europe, but also grows wild in North America [1].

Bilberry is a popular fruit to snack on in Europe. People usually collect the berries from wild plants, since bilberries are almost impossible to cultivate and harvest. The berries are eaten fresh, frozen, or dried. They can also be made into jams, juices, liquors, pies, and yogurts [1, 2+].



  • Good source of fiber, vitamins, and minerals
  • Antioxidant and anti-inflammatory
  • May improve eye disorders, ulcerative colitis, and fatty liver disease
  • May lower blood pressure, sugar, and cholesterol
  • May help prevent brain diseases, infections, and cancer


  • Fresh bilberries are difficult to find outside Europe
  • Some benefits are insufficiently investigated
  • Possible drug interactions

Traditional and Modern Use

Bilberries have been used medically since the Middle Ages for conditions such as [1]:

  • Gallbladder disorders
  • Scurvy
  • Cough
  • Tuberculosis
  • Sore throat

More recently, fruit and leaf extracts started being used as remedies for [1]:

  • Diarrhea
  • Mouth and throat inflammation
  • Menstrual cramps
  • Diabetes
  • Eye diseases
  • Blood flow
  • High cholesterol

However, many of them remain scientifically unproven.

Bilberry Health Benefits

SelfDecode has an AI-powered app that allows you to see how bilberry benefits your personal genetic predispositions. These are all based on clinical trials. The orange neutral faces denote a typical genetic risk of developing conditions that bilberry counteracts.

Effective for:

1) Nutritional Boost

100 g of bilberries will give you [3]:

  • Calories: 42
  • Carbs: 11.5 g (8.7 g sugars and 2.8 g fiber)
  • Proteins: 0.7 g
  • Fats: 0.5 g
  • Vitamin C: 44 mg (48% of recommended daily intake)
  • Vitamin E: 2.1 mg (14% of recommended daily intake)
  • Manganese: 3.3 mg (66% of recommended daily intake)
  • Potassium: 103 mg (3% of recommended daily intake)

This means that bilberries combine a low-calorie count with a high vitamin and mineral content. They’re especially rich in vitamin C and manganese.

2) Antioxidant Activity

The main active components of bilberries are their anthocyanins, powerful antioxidants. These plant pigments also give bilberries their vivid red-to-blue color [4].

Bilberries are among the richest anthocyanin sources, supplying 300-700 mg per 100 g berries. The main ones are [2+, 5+]:

  • Cyanidin
  • Delphinidin
  • Malvidin
  • Peonidin
  • Petunidin

Other less abundant phenolic compounds in the berries include quercetin, myricetin, catechins, resveratrol, and caffeic and coumaric acid. Leaves are much lower in anthocyanins but contain higher amounts of these phenolic compounds [6+, 7, 8, 9, 10+].

Fruit mixes, juices, and supplements with bilberries raised blood and urine antioxidant levels and enzyme activity in 3 clinical trials on almost 200 people. Oral supplements had good bioavailability in rats and increased blood anthocyanins after only 15-30 minutes [11, 12, 13, 14, 15].

In cells and test tubes, the extract increased the activity and production of antioxidant enzymes and neutralized free radicals [16, 17, 18, 19, 20, 21].

Clinical studies suggest that various anthocyanins, which are highly concentrated in bilberries, help boost antioxidant defense.

Possibly Effective for:

3) Eye Health

According to folk wisdom, bilberries improve eye health and protect against multiple conditions such as glaucoma, cataracts, and eye fatigue.

An extract with bilberry anthocyanins improved vision in a clinical trial on over 300 people with glaucoma. Two similar extracts (standardized to 36% anthocyanins) improved blood retinal flow and reduced eye pressure in 4 trials on over 350 healthy people. These studies suggest that bilberry may, indeed, both improve and prevent glaucoma [22, 23, 24, 25, 26].

More jobs require people to stare at computer screens all day, while phone use often makes the remaining time. This is associated with two conditions: eyestrain and dry eye. In both, reduced tear production impairs vision. Standardized bilberry extracts increased tear production in 3 clinical trials on over 100 people with these conditions [27, 28, 29].

Bilberry extract also improved focus adjustment and night vision in a clinical trial on 30 adults with nearsightedness. A drug with bilberry anthocyanins (Difrarel) slowed the progression of this condition in a clinical trial on 32 children and a study in Guinea pigs [30, 31, 32].

In animals, bilberry reduced eye inflammation and eye nerve damage caused by free radicals, UV radiation, and excessive light exposure. This suggests that bilberry may prevent blindness and cataracts [33, 34, 35, 36, 37, 38, 39].

To sum it up, research backs up the traditional claims that bilberry improves eyesight. Supplementing is a good idea if you want to take greater care of your eyes, whether you’re at risk of glaucoma or use the computer a lot.

Nevertheless, note that bilberries are not approved by the FDA for any eye conditions. You may try this fruit if you and your doctor determine that it could be appropriate for improving your eye health. Remember that taking bilberries should never be done in place of what your doctor recommends or prescribes.

Decent evidence shows that bilberry might improve eyesight, especially in glaucoma patients and people who are frequently exposed to artificial blue light. Large-scale studies are needed, though.

4) Inflammation

Bilberries (250-500 g/day) and their juice (330 mL/day) reduced blood inflammation markers (such as IL-1b, IL-6, VEGF, and CRP) in 3 clinical trials on over 100 people. They helped those with gum disease, metabolic syndrome, and high risk of heart disease [40, 41, 42]

Bilberries and their extracts also reduced inflammation in mice. Anthocyanins from the berries also relieved itching in mice with eczema [43, 44, 45, 46].

In a clinical trial on 59 people with eczema and psoriasis, bilberry seed oil applied to the skin improved redness, itching, scales, and disease severity [47].

In cells, bilberry anthocyanins blocked the major inflammatory hub, NF-kB, and reduced the production and activity of pro-inflammatory [48, 49, 50]:

While increasing the production of anti-inflammatory cytokines (IL-10 and IL-22) [48].

All in all, bilberry seems to be a safe remedy for a range of chronic inflammatory diseases. Bilberries are not approved for inflammatory issues, but you may try them as an aid if you and your doctor determine that they could help you.

Limited human evidence suggests that bilberries might help lower chronic inflammation, but further work is needed.

5) High Blood Cholesterol

In 6 clinical trials on over 400 people at risk of heart disease, bilberry fruits (65-300 g/day) and anthocyanins reduced blood triglycerides, total and LDL cholesterol while increasing HDL [51, 52, 53, 54, 55, 56].

The extract lowered fat and cholesterol in the blood and liver of rats. It also reduced artery clogging in mice by lowering blood fat and protecting LDL from damage [57, 58, 59, 60, 61, 62].

Although limited, the existing evidence suggests that bilberries help lower blood cholesterol. If you have high cholesterol levels, you may discuss with your doctor the potential benefits of including them in your diet.

6) Blood Flow

In addition to lowering blood cholesterol, bilberries may also protect your heart by improving blood flow and helping lower blood pressure.

Juice from bilberries and other polyphenol-rich fruits (500 mL/day) relaxed blood vessels in a clinical trial on over 100 people. It had a stronger effect on those who already suffered from high blood pressure [63].

An extract standardized to 36% anthocyanins (600 mg/day) improved spider veins in a clinical trial on over 1k people [64].

Bilberry anthocyanins increased blood vessel tone and blood flow in hamsters. According to cell-based studies, they work similarly to commonly-used drugs for lowering blood pressure (blocking angiotensin-converting enzyme) [65, 66].

To sum up, the existing evidence suggests that bilberries may improve blood flow. Discuss with your doctor if they may be beneficial in your case.

7) High Blood Sugar

Bilberry fruits (300-400 g/day) and extracts lowered blood sugar in 3 clinical trials on over 150 people with or at risk of type 2 diabetes. Bilberry also increased insulin release and sensitivity, which is important for preventing insulin resistance. Plus, it reduced sugar and insulin spikes after meals [67, 68, 69].

Similarly, a cup of bilberry fruits or 1-2 glasses of the juice reduced sugar, insulin, and GLP-1 spikes after eating a carbohydrate-rich meal in 6 trials on almost 100 healthy people [70, 71, 72, 73].

Bilberry (fruit and leaf extracts) also improved diabetes in animals and prevented gut, kidney, and eye complications. It blocked an enzyme that breaks down complex sugars called alpha-glucosidase in test tubes, which is perhaps why this plant can lower blood sugar after meals [74, 75, 76, 77, 78, 79, 9, 80].

Although the evidence is limited, bilberries seem a good natural strategy to help lower blood sugar levels based. Further research should determine how they may be used therapeutically.

Insufficient Evidence for:

1) Weight Loss

In a clinical trial on over 100 overweight women, bilberry extract (about 100 g berries per day) slightly reduced weight and waist size [81].

In animals fed a high-fat diet, bilberry reduced weight gain and fat buildup in fatty tissues, blood, and liver. Various forms of the plant provided the same benefits – from the berries to their anthocyanins to the leaves. In cell studies, anthocyanin-rich bilberry extracts prevented fat cells from growing and accumulating in tissues [82, 83, 84, 85, 86].

Bilberry may do more than just boost weight loss. It also protected obese animals from complications such as diabetes, inflammation, high blood pressure, and gut microbiome imbalances [84, 87, 85, 86, 88].

Although promising, the existing evidence is insufficient to support the role of bilberries in weight loss. Further clinical research is needed.

2) Kidney and Liver Support

In a clinical trial on 74 people with non-alcoholic fatty liver disease, bilberry anthocyanins improved markers of liver injury. The same was confirmed in mice with anthocyanin-rich bilberry extracts: these reduced fat buildup, inflammation, and scarring in the liver [89, 90, 91].

The antioxidant and anti-inflammatory activity of bilberry extracts protected the livers and kidneys of mice and rats from the damage caused by:

Again, the evidence is promising but insufficient to claim that bilberries protect from kidney and liver damage. More clinical studies are required.

3) Diarrhea

In one trial, bilberries improved mild to moderate ulcerative colitis symptoms in 12 out of 13 people. By the end of the trial, 8 people were symptom-free. They used a combination of the dried berries and their concentrated juice. Bilberries and their anthocyanins also improved colitis in mice [102, 103].

In contrast, a mixture of powdered bilberry fruits, slippery elm bark, agrimony, and cinnamon sticks was ineffective for diarrhea. It only improved pain, bloating, and gas in a trial on 21 people with diarrhea-predominant IBS [104+].

Bilberries may also improve diarrhea and gut health by restoring the gut microbiome. In rats, medium (but not high) doses of bilberry anthocyanin extract promoted the growth of the beneficial gut bacteria over the harmful ones [105].

Two clinical trials (with partially mixed results) and two animal studies cannot be considered sufficient evidence to support the benefits of bilberry for diarrhea.

It’s uncertain whether bilberries can improve diarrhea. Larger, more robust studies should investigate this potential use.

4) Cancer

Below, we will discuss some preliminary research on the anticancer activity of bilberries. It’s mainly in the animal and cell stage and further clinical studies have yet to determine if their compounds are useful in cancer therapies.

Do not under any circumstances attempt to replace conventional cancer therapies with bilberries, their components, or any other dietary interventions. If you want to use them as supportive measures, talk to your doctor to avoid any unexpected interactions.

In a small trial on 25 people with colorectal cancer, bilberry extract increased anthocyanin levels in the blood, bowels, and urine. This shows that the berries’ active components can be absorbed and distributed throughout the body. In turn, the extract slightly reduced tumor growth and a cancer-promoting protein (IGF-1) [106].

In animal studies, bilberry reduced the development, growth, and survival of the following cancer types:

The extract also blocked vessel formation, suggesting it may help starve tumors of the blood supply they need to grow [113, 114].

Chemotherapy Side Effects

In hamsters, bilberry extract improved mucositis – painful inflammation of the mouth lining caused by chemo drugs. In an observational study on 20 children with cancer, those who used a multi-herbal formula with bilberry, plume poppy, and echinacea experienced fewer side effects; they had fewer mouth wounds, pain, bleeding, and difficulty eating [115, 116].

Bilberry extract also protected rats and mice from the toxic effects of anticancer drugs on the heart, bone marrow, kidneys, ovaries, and ears [117, 118, 95, 119, 120].

Despite its anti-cancer potential, more research is needed to determine the effectiveness and safety of bilberry in cancer patients (either alone or in combination with chemotherapy).

5) Chronic Fatigue

Some people claim that bilberries and similar fruits improved their chronic fatigue syndrome. Studies are lacking to back them up, but bilberries do have some anti-fatigue potential. Anthocyanins from the berries reduced fatigue in one clinical trial on 10 people with fibromyalgia and in another on 20 people with eyestrain [121, 27].

Uses Lacking Evidence:

No clinical evidence supports the use of bilberries for any of the conditions listed in this section.

Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies listed below should not be interpreted as supportive of any health benefit.

6) Brain Health

Bilberry extract preserved brain function in mice with Alzheimer’s. It acted by promoting the formation of non-toxic beta-amyloid proteins in the brain over the harmful ones [122, 123].

Rats with Parkinson’s eating bilberries had more immune cells move to the injured brain regions, which helps repair brain damage [124].

Diabetes affects cognitive function by increasing brain cell damage and altering neurotransmitter levels. Feeding bilberries to diabetic mice prevented these effects [125].

In test tubes, bilberry extract protected brain cells from:

  • Beta-amyloid buildup [123, 126]
  • An anticancer drug (5-fluorouracil) [127]
  • Free radicals [128]

7) Improving Skin Appearance

Bilberry extract and its antioxidants protected human skin cells from UV radiation. They reduced free radical production and prevented DNA and skin cell damage [129, 130, 131].

The extracts have one drawback: they can’t penetrate the skin easily. Liposomes with bilberry extract overcame this problem in a study on human skin, providing much better UV protection [132].

8) Infections

Bilberry extract was active against an array of microbes in test tubes, including those causing:

  • Food poisoning (Staphylococcus, Salmonella, Clostridium, Bacillus) [133, 134+, 135]
  • Stomach ulcers (Helicobacter pylori) [134+]
  • Pneumonia (Streptococcus pneumoniae) [136]
  • Antibiotic-resistant infections (Staphylococcus aureus) [135]
  • Thrush (Candida) [137]

It’s important to note that these are very preliminary results that have not yet been studied in humans or even in animals. Further research should determine if bilberries are effective against infections caused by these organisms when ingested in normal doses.

Possibly Ineffective for:

9) Heavy Metal Detox

Bilberry anthocyanins are traditionally claimed to detox heavy metals by trapping (chelating) them. These compounds do bind some toxic metals (cadmium, lead, zinc), but also essential minerals (iron, and manganese). All in all, they are probably less efficient than commonly-used chelation protocols (with EDTA, dimercaprol, penicillamine) [138, 139, 140].

Most importantly, chelation therapy is often fraudulently proposed to improve conditions such as autism, Alzheimer’s, and heart disease. Consult your doctor before trying to replace proven therapies for these conditions with bilberry or chelation protocols [141, 142, 143+, 144+].

Likely Ineffective for:

10) Night Vision

According to a myth, WWII Royal Air Force pilots improved their night vision by eating bilberry jam (or carrots in some versions). However, their high accuracy at hitting their targets was likely due to another well-kept secret of theirs – the development of radar technology [145+].

Indeed, bilberry failed to improve night vision in 3 trials on 49 people with normal vision and a meta-analysis of 12 studies. It was only effective in one trial on 30 nearsighted people [146, 147, 148, 149, 30].

Bilberry Dosage & Supplements

Tea & Extracts

Health food stores and online vendors sell a wide variety of bilberry teas. The bags can contain dried berries, leaves, or both.

Alternatively, you can buy dried bilberries and make the tea yourself as follows:

  • Place 1-3 teaspoons of bilberries in a cup
  • Add boiling water
  • Let steep for 10-15 minutes

Bilberry extracts can be taken as tablets, capsules, and liquids. Eye drops with the extract are also available. All extracts should be standardized to their anthocyanin content. The best-researched ones are [150+, 29+, 23+]:

  • Bilberry VMA (25% anthocyanins)
  • Mirtoselect (36% anthocyanins)
  • Mirtogenol (80 mg Mirtoselect plus 40 mg French pine extract)


Because bilberries are not approved by the FDA for any conditions, there is no official dose. Users and supplement manufacturers have established unofficial doses based on their experience.

The doses most commonly used in clinical trials were:

  • Eye disorders: 160-480 mg extract (59-180 mg anthocyanins) per day
  • Inflammation: 250-500 g berries per day
  • Diabetes: 50-300 g berries per meal
  • Cholesterol: 65-300 g berries or 320 mg extract per day
  • Weight loss: 100 g berries per day
  • Ulcerative colitis: 160 g/day of a supplement with 60% dried berries and 26% juice
  • Fatty liver disease: 320 mg anthocyanins per day

How Long Does It Take to Work?

In clinical trials, bilberries and their extracts were generally taken for 8-12 weeks and benefits were rarely seen before one month. Chronic conditions were followed up for 6-12 months.

Bilberry Side Effects & Safety

Bilberry is considered safe since people used it as a staple food for millennia. Indeed, a megadose of bilberry anthocyanins (180 mg/kg per day) for 6 months had no toxic effects [1].

Of all the clinical trials with bilberry extracts, only 2 reported the following mild adverse effects [102+, 104+]:

  • Nausea
  • Gas
  • Hard stools
  • Dying of the tongue and stools
  • Mild heartburn

These were reported in people with IBS or ulcerative colitis and may not have been a direct adverse effect of the extract.

Bilberries are thought to be safe when consumed as food, but high doses may cause gastrointestinal upset. The side effects of long-term supplementation remain unknown.

Allergies and Food Sensitivities

Bilberry allergies are extremely rare but possible. Two cases of allergies to unidentified berries (either bilberries or blueberries) have been reported. One girl only had mild symptoms (shortness of breath and back itching), but another woman had a life-threatening allergic reaction (anaphylaxis) [151+, 152+].

People with food sensitivities might want to avoid bilberries. The berries may contain vaso-active amines, benzoates, and salicylates – all of which can trigger an inflammatory reaction in sensitive or intolerant people. The dried berries will also contain sulfites [153].

Drug Interactions

To help avoid interactions, your doctor should manage all of your medications carefully. Be sure to tell your doctor about all medications, vitamins, or herbs you’re taking. Talk to your healthcare provider to find out how bilberries might interact with something else you are taking.

Bilberries may lower blood pressure and sugar levels. They may cause excessive drops in people taking medication for high blood pressure and/or diabetes. Consult your doctor before combining bilberries or their extracts with these medications.

Pregnancy and Breastfeeding

Data on the safety of bilberries during pregnancy and breastfeeding are lacking; it’s better to avoid extracts and stick to food doses in these situations [154].

For Dogs

Bilberries or their extracts (~3 g or 0.2 mg anthocyanins per kg per day) may protect dogs from cataracts and other disorders. Consult your vet about their dosage and safety [155].

Limitations and Caveats

The effects of bilberry on several eye disorders, gum disease, diarrhea, and oral mucositis were investigated in a few clinical trials with small populations. The other benefits were only investigated in animals and cells. Clinical studies are required to confirm the preliminary results.

Some studies were funded by the companies producing the extracts and drugs tested (Kukje Pharma, Wakasa Seikatsu, Indena, ProViva, Probi, Aromatech, TINE, Symrise) or included workers among the authors [22, 28+, 29+, 73, 51, 63+, 104+, 115+].

Bilberries are easy to find in Europe, while they’re more of a rarity in the US. If you’re lucky, you might be able to find frozen bilberries in some stores.


Bilberries are antioxidant-packed relatives of the North American blueberry. They’re the richest source of anthocyanins: colorful plant pigments that may protect you from free radicals. Bilberries may help main heart, brain, gut, and liver health.

Clinical studies confirmed the benefits of these berries for eyesight, especially if you’re looking to protect your eyes from frequent computer use or glaucoma.

Be careful with bilberries if you have food intolerances, though. These berries contain some antinutrients that can trigger symptoms in sensitive people.

Further Reading

About the Author

Carlos Tello

Carlos Tello

PhD (Molecular Biology)
Carlos received his PhD and MS from the Universidad de Sevilla.
Carlos spent 9 years in the laboratory investigating mineral transport in plants. He then started working as a freelancer, mainly in science writing, editing, and consulting. Carlos is passionate about learning the mechanisms behind biological processes and communicating science to both academic and non-academic audiences. He strongly believes that scientific literacy is crucial to maintain a healthy lifestyle and avoid falling for scams.


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