Quick Summary

Bilberry (Vaccinium myrtillus) is a berry rich in anthocyanins and polyphenols, traditionally used in diets and herbal medicine for various health conditions. Scientific research has investigated its potential benefits for type 2 diabetes mellitus (T2DM), vision disorders, circulatory diseases, cardiovascular health, ulcerative colitis, and non-alcoholic fatty liver disease (NAFLD). Evidence from randomized controlled trials (RCTs) and systematic reviews shows mixed results, with some indications of modest benefits on glycemic control (HbA1c), inflammation markers, and lipid profiles but overall inconclusive or limited clinical data due to small sample sizes and heterogeneity. Bilberry extracts are generally well tolerated with rare serious adverse events reported, though safety data remains incomplete. More high-quality, long-term clinical studies are needed to clarify efficacy, optimal dosing, and safety profiles.

What is it

Bilberry is a small dark-blue berry from the plant species Vaccinium myrtillus, related to blueberries. It has been used traditionally as a food and herbal remedy, primarily found in Europe and North America. Bilberries contain bioactive compounds including anthocyanins, flavonoids, and polyphenols, which contribute to their distinctive color and potential health effects.

Traditional Uses

Traditionally, bilberry has been used to support vision health, improve blood circulation, and manage symptoms related to diabetes and inflammation. It has also been employed in herbal medicine for gastrointestinal ailments and to promote overall wellness.

Active Compounds

  • Anthocyanins: Pigments with antioxidant properties thought to support vascular and eye health.
  • Polyphenols: Plant compounds that may reduce oxidative stress and inflammation.
  • Flavonoids: Bioactive compounds contributing to anti-inflammatory and vascular benefits.

Potential Benefits with Evidence Levels

  • Glycemic control in type 2 diabetes mellitus: Low to moderate evidence. A meta-analysis of 8 RCTs (409 participants) showed a marginally significant reduction in HbA1c (weighted mean difference -1.63%, p=0.06) and a non-significant decrease in fasting blood glucose. Some systematic reviews suggest potential complementary benefits, but evidence is limited by heterogeneity and small sample sizes.
  • Improvement in lipid profile: Low evidence. Clinical trials reported a trend toward lowered triglycerides and total cholesterol, with a significant increase in LDL cholesterol in long-term studies. Evidence is inconsistent, and no definitive lipid-lowering effect is established.
  • Anti-inflammatory effects: Limited human evidence. Bilberry extracts reduced fecal calprotectin in ulcerative colitis patients in a controlled trial, indicating anti-inflammatory activity. Some biomarkers of inflammation (IL-6, hs-CRP) showed non-significant reductions in meta-analyses.
  • Visual function/eye health: Insufficient clinical evidence. Traditional use and early studies suggest benefits for retinal and ocular health; however, current human RCTs have not consistently demonstrated clinically meaningful improvements in age-related macular degeneration or visual function.
  • Cardiovascular and metabolic health: Preliminary and inconsistent evidence. Some clinical and preclinical studies report antioxidant and vasoprotective properties of bilberry anthocyanins, but trials show mixed effects on blood pressure and cardiovascular risk markers.
  • Gut health and intestinal disorders: Very limited evidence. Some data from a multicenter trial indicates bilberry anthocyanin-rich extract may reduce intestinal inflammation in moderate-to-severe ulcerative colitis without significant superiority over placebo.

Side Effects

Bilberry extracts and supplements appear generally safe and well tolerated in humans. Few mild adverse effects have been reported, including occasional gastrointestinal symptoms and rare genitourinary problems, mainly observed with related zinc-containing preparations. No serious safety concerns have been consistently identified.

Drug Interactions

There is limited information on herb-drug interactions with bilberry. Caution is advised when bilberry is used alongside antidiabetic medications due to the potential for additive effects on blood sugar control. No well-documented pharmacokinetic interactions have been reported.

Who Should Avoid It

No specific contraindications have been identified based on current evidence. However, pregnant and breastfeeding women should exercise caution and consult healthcare providers before use due to insufficient safety data. Individuals on antidiabetic medications should also consult medical advice before using bilberry supplements.

Evidence Limitations

  • Most available clinical studies have small sample sizes, short durations, and heterogeneity in bilberry preparations and dosages.
  • Many trials report borderline or non-significant effects, limiting strong conclusions.
  • Lack of large, well-designed double-blind, placebo-controlled RCTs.
  • Limited data on long-term safety, optimal dosing, and herb-drug interactions.
  • Some clinical claims are based on traditional use or preclinical studies without robust clinical confirmation.

References

Last Reviewed

April 2024

Disclaimer

This information is provided for educational purposes only and is not intended as medical advice. The potential health benefits of bilberry are based on limited and preliminary scientific evidence. Always consult a healthcare professional before starting any new supplement, especially if you have underlying health conditions or are taking medications. Your individual needs and health status should guide any decisions regarding herbal product use.