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Blueberry

The bilberry - also known as the blueberry - is also known as the European bilberry. Its Latin name is accinium myrtillus L. The bilberry grows on a low-growing bush that belongs to the Ericaceae family (1, 2). The berries themselves are tasty and have a black-blue color. Bilberries are known to be one of the richest sources of a highly potent class of plant antioxidants called anthocyanins (1, 2). Bilberries are native to Europe and North America (1, 2). The wild European bilberry is one of the most important natural resources in Finland, where it is harvested by hand in forests for domestic use and sale (3).

Areas of application

Bilberries and their extracts are used for the prevention of cataracts and glaucoma, urinary tract infections, multiple sclerosis, chronic fatigue syndrome, colic, fever, varicose veins and hemorrhoids. Blueberries are also used to improve blood circulation and as a laxative. Some women use bilberries to relieve labor pains and as a tonic after a miscarriage. The dried fruit and leaves are used to treat diarrhea.

Tea made from the dried leaves is used for sore throats and swelling or inflammation of the mouth or throat and pharynx. In the medical field, bilberry juice is used as a contrast agent in magnetic resonance imaging. Such contrast agents enable radiologists to better interpret the images. Some people inhale the smoke of burnt bilberry blossoms as a treatment for mental illness.

The benefits of bilberries and bilberry extracts

Bilberry is well known for its therapeutic efficiency as a powerful antioxidant. Most of the scientific research has focused on a group of compounds known as anthocyanins, as these compounds are considered to be the most pharmacologically active components of bilberry (4). Blueberries and blueberry extract have been studied primarily for two indications: Atherosclerosis/diabetes and eye health (5). Although there are some very promising studies on the benefits of bilberry extracts for treating atherosclerosis and promoting eye health in animal models (1, 7-9), human studies have produced conflicting results (2, 5).

One promising human study worth mentioning involved an investigation of the effects of bilberry extract in combination with lutein and fish oil on symptoms of asthenopia (eye strain or fatigue). Compared to a placebo group, the group treated with these active ingredients showed significant improvements in symptoms of asthenopia and mental fatigue (10). In today's world, where many people spend a lot of time in front of the computer every day, bilberry extract could prove to be quite useful in promoting eye health. Bilberries, just like their cousin cranberries, may help prevent bladder infections by preventing bacteria from adhering to the walls of the bladder. The blueberry fruit is rich in fiber, which could support normal digestive function. It also contains vitamin C and other antioxidants.

Side effects

Rats have been given doses of up to 400mg bilberry extract per kilogram of body weight with no toxic side effects observed. Long-term administration of doses in the range of 180 mg of anthocyanins per kilogram of body weight to human volunteers over a period of 6 months produced no toxic effects (5, 6). A study review that included studies with a total of over 2000 subjects taking bilberry extract reported only mild side effects affecting the digestive system, skin or nervous system (5, 6).

Recommended intake for bilberry extract

An appropriate dosage for bilberry supplements depends on various aspects, including age, health status and other aspects. Most human and animal studies used dosages ranging from 200 to 500mg of anthocyanins (5). Supplements usually contain between 100mg and 300mg of bilberry extract. The whole fresh fruit contains between 0.1 and 0.25% anthocyanins and concentrated extracts contain between 30 and 40% anthocyanins. At this time, there is not enough scientific information to determine an appropriate dosage range for bilberry supplements, so follow the dosage instructions on the label or consult a doctor or pharmacist before taking.

Bilberry extract supplements

Despite the large number of scientific studies on the health benefits of bilberry extract, this extract is not yet included in many bodybuilding supplements. This is most likely due to the fact that health benefits are not usually associated with gains in strength and/or muscle mass.

Combinations with other supplements

Bilberry extract can be combined with other phytoantioxidants and antioxidants from other foods to create a comprehensive antioxidant formula. Another popular combination is to combine bilberry extract with other phytonutrients such as lutein and zeaxanthin that target eye health. As mentioned above, combining bilberry extract with lutein and fish oil can help reduce eye strain and mental fatigue (10). Furthermore, bilberry extract can be taken with products containing large amounts of carbohydrates to optimize the effect of insulin.

Are there any safety concerns?

As you would expect from a food product, blueberries are very safe to consume and absolutely harmless (5). As bilberry extracts inhibit blood clotting, very high doses should be used with caution by patients who suffer from an increased bleeding tendency or a blood clotting disorder, or who are taking medication to inhibit blood clotting (5). Not enough is known about the safety of taking bilberry leaf orally, so it is best to avoid taking it.

Precautions and warnings

Pregnancy and breastfeeding: Bilberry fruit is probably safe when consumed in the amounts commonly found in food. However, not enough is known about the consumption of larger amounts used for medicine or as an extract in supplements.

Diabetes: Blueberry products can lower blood sugar levels in diabetics. For this reason, diabetics should watch for signs of low blood sugar levels and carefully monitor their blood sugar levels when taking blueberry supplements. It is possible that the dosage of diabetes medication used may need to be adjusted by the treating physician.

Surgeries: Blueberry products can affect blood sugar levels and interfere with blood sugar control during or after surgery. For this reason, you should stop taking blueberry supplements 2 weeks before planned operations.

Are there any interactions with medication?

You should be careful when combining blueberry products with the following medications:

Diabetes medications

Bilberry leaves can lower blood sugar levels. Diabetes medication is used to lower blood sugar levels. The combination of blueberry leaves and diabetes medication can result in an excessive drop in blood sugar levels. For this reason, blood sugar levels should be closely monitored. It is possible that the dosage of diabetes medication used may need to be adjusted by the treating doctor.

Are there any interactions with medicinal plants or supplements?

There are no known interactions with medicinal plants or supplements.

Are there any interactions with food?

There are no known interactions with food.

References

  1. Mauray A, et al. Nutrigenomic analysis of the protective effects of bilberry anthocyanin-rich extract in apo E-deficient mice. Genes Nutr. 2010;5:343-353.
  2. Canter PH, et al. Anthocyanosides of vaccinium myrtillus (Bilberry) for night vision-a systematic review of placebo-controlled trials. Survey of Opthalmology. 2004;49(1):38-50.
  3. Latti AK, et al. Analysis of anthocyanin variation in wild populations of Bilberry (Vaccinium myrtillus L.) in Finland. J Agric Food Chem. 2008;56:190-196.
  4. Yao Y & Vieira A. Protective activities of Vaccinium antioxidants with potential relevance to mitochondrial dysfunction and neurotoxicity. Neurotoxicity. 2007;28:93-100.
  5. Monograph. Vaccinium myrtillus (bilberry). Alternative Medicine Review. 2001;6(5):500-504.
  6. Eandi M. Post-marketing investigation on Tegens" preparation with respect to side effects. 1987. Cited in Morazzoni P, Bombardelli E. Vaccinium myrtillus I. Fitoterapia 1996;67:3-29.
  7. Mauray A, et al. Bilberry anthocyanin-rich extract alters expression of genes related to atherosclerosis development in aorta of apo E-deficient mice. Nutr Metab Cardiovasc Dis. 2012;22(1):72-80.
  8. Mauray A, et al. Atheroprotective effects of bilberry extracts in apo E-deficient mice. J Agric Food Chem. 2009;57(23):11106-11111.
  9. Helmstädter A & Schuster N. Vaccinium myrtillus as an antidiabetic medicinal plant--research through the ages. Pharmacy. 2010;65(5):315-321.
  10. Kawabata F, Tsuji T. Effects of dietary supplementation with a combination of fish oil, bilberry extract, and lutein on subjective symptoms of asthenopia in humans. Biomed Res. 2011 Dec;32(6):387-93.