Bilberry's therapeutic uses

DEFINITION: Natural plant product used to treat specific health conditions.

PRINCIPAL PROPOSED USES: None

OTHER PROPOSED USES: Diabetes, diabetic retinopathy, easy bruising, hemorrhoids, minor injuries, surgery support, varicose veins, diarrhea, various eye problems, blood sugar control, cholesterol control, anti-inflammatory, antioxidant

Overview

Often called European blueberry, the bilberry is closely related to American blueberry, cranberry, and huckleberry. Its meat is creamy white instead of purple, but like blueberries, bilberries are traditionally used in the preparation of jams, pies, cobblers, and cakes.

Bilberry fruit also has a long medicinal history. In the twelfth century, Abbess Hildegard of Bingen wrote about the bilberry’s usefulness in inducing menstruation. Over subsequent centuries, the list of uses for the bilberry grew to include a bewildering variety of possibilities, from bladder stones to typhoid fever.

Therapeutic Dosages

The standard dosage of bilberries is 120 to 240 milligrams (mg) twice daily of an extract standardized to contain 25 percent anthocyanosides.

Therapeutic Uses

The modern use of the bilberry dates back to World War II, when British Royal Air Force pilots reported that a good dose of bilberry jam just before a mission improved their night vision, often dramatically. Subsequent investigation showed that bilberries contain biologically active substances known as anthocyanosides. Some evidence suggests that anthocyanosides may benefit the retina, as well as strengthen the walls of blood vessels, reduce inflammation, and stabilize tissues containing collagen (such as tendons, ligaments, and cartilage). For this reason, bilberries have been suggested as a supplement for several eye conditions, including night vision, retinopathy, macular degeneration, glaucoma, and cataracts.

However, neither anecdote nor basic scientific evidence of this type can prove a treatment effective. Only double-blind, placebo-controlled studies can do that. Regarding night vision, the balance of the evidence suggests that bilberries may not be as helpful as previously thought. Still, evidence from scientific studies shows that bilberries might be helpful for macular degeneration and diabetic retinopathy.

Some studies have investigated the fruit's impact on blood pressure, but the results are mixed. If it positively impacts blood pressure, it is because of its high polyphenol content. One double-blind study suggested that bilberries might be helpful for hemorrhoids. Some studies suggest bilberries can lower blood sugar and cholesterol levels. These findings indicate its potential benefits for people with diabetes. Animal studies also suggest that bilberry leaves (rather than the fruit) may be help to improve blood sugar control in people with diabetes and also lower blood triglycerides.

Finally, because the anthocyanosides in bilberries resemble the oligomeric proanthocyanidin complexes (OPCs) found in grape seed and pine bark, the bilberry has been recommended for all the same uses as those substances, including easy bruising, varicose veins, minor injuries, and surgery support.

Scientific Evidence

Night vision. A double-blind crossover trial of fifteen individuals found no short- or long-term improvements in night vision attributable to bilberries. Similarly, negative results were seen in a double-blind, placebo-controlled crossover trial of eighteen subjects and another of sixteen subjects.

In contrast, two much earlier controlled, but not double-blind, studies of the bilberry found that the herb temporarily improved night vision. However, the effect was not found to persist with continued use. A later double-blind, placebo-controlled study on forty healthy subjects found that a single dose of bilberry extract improved visual response for two hours. Visual benefits have also been reported in other small trials, but these studies did not use a placebo control group and are therefore not valid as evidence.

In 2023, a double-blind placebo-controlled study noted significant improvement in pupillary response after participants were given bilberries when compared to the placebo group. A 2017 study noted improvements in eye function and decreased eye fatigue when individuals were given bilberries. Visual improvements were not the only facet of eye health studied, as studies have found benefits in treating other eye health conditions with bilberries.

Hemorrhoids. In a four-week, double-blind, placebo-controlled study of forty people with hemorrhoids, oral use of bilberry extract significantly reduced hemorrhoid symptoms compared with a placebo.

Diabetic retinopathy. A double-blind, placebo-controlled trial of bilberry extract in fourteen people with diabetic retinopathy or hypertensive retinopathy (damage to the retina caused by diabetes or hypertension, respectively) found significant improvements in the treated group. However, the small size of this study makes the results less than fully reliable. Other studies are also cited as indicating benefits, but they were not double-blind and, therefore, mean little.

Muscle damage and inflammation. Studies investigating the bilberry's impact on athletes' muscle recovery have rendered no positive indications. Though the fruit has high levels of antioxidants, its implications for athletes are minimal.

Safety Issues

Bilberry fruit is a food and, as such, is quite safe. Enormous quantities have been administered to rats without toxic effects. One study of 2,295 people who were given bilberry extract found a 4 percent incidence of side effects such as mild digestive distress, skin rashes, and drowsiness. Although safety in pregnancy has not been proven, clinical trials have enrolled pregnant women. Safety in young children, nursing women, or those with severe liver or kidney disease is not known. There are no known drug interactions. Bilberries do not appear to interfere with blood clotting.

Little is known about the safety of bilberry leaf. Based on animal evidence that it can reduce blood sugar levels in people with diabetes, it is possible that use of bilberry leaf by people with diabetes could require a reduction in drug dosage. Those taking medications to reduce blood sugar may find that bilberry leaf (not fruit) amplifies the effect, and they may need to reduce their dose of medication.

Bibliography

"Bilberry." Icahn School of Medicine at Mount Sinai, www.mountsinai.org/health-library/herb/bilberry. Accessed 20 Aug. 2023.

"Bilberry." National Center for Complementary and Integrative Health, www.nccih.nih.gov/health/bilberry. Accessed 20 Aug. 2023.

“Bilberry Information.” Mount Sinai, www.mountsinai.org/health-library/herb/bilberry. Accessed 5 Sept. 2024.

Lynn, A., et al. "Effect of Bilberry Juice on Indices of Muscle Damage and Inflammation in Runners Competing a Half-Marathon: A Randomised, Placebo-Controlled Trial." Journal of the International Society of Sports Nutrition, vol. 15, no. 22, 2018, doi:10.1186/s12970-018-0227-x.

Sekikawa, Takahiro, et al. "The Effect of Consuming an Anthocyanin-containing Supplement Derived from Bilberry (Vaccinium Myrtillus) on Eye Function: A Randomized, Double-Blind, Placebo-Controlled Parallel Study." Functional Foods in Health and Disease, vol. 11, no. 3, Mar. 2021, doi.org/10.31989/ffhd.v11i3.782. Accessed 5 Sept. 2024.

Tjelle T.E., et al. "Polyphenol-Rich Juices Reduce Blood Pressure Measures in a Randomized Controlled Trial in High Normal and Hypertensive Volunteers." British Journal of Nutrition, vol.114, no. 7, 2015, pp. 1054-1063.