Bilberry supplements and heart and metabolic risk factors
What it found
Bilberry and anthocyanin supplements have shown antioxidant, anti-inflammatory, blood sugar and cholesterol effects in lab tests and animals, but results in people are mixed.
The authors say larger, well-designed trials are needed before the benefits in type 2 diabetes or heart disease are clear.
What they found
Studies in people
Antioxidant effects in people
Human trials gave mixed results. Some found small improvements in antioxidant status or cholesterol, while others found no change in antioxidant or oxidative stress markers.
Inflammation in people
Several human trials found that bilberry or anthocyanin supplements lowered markers of inflammation such as hsCRP and inflammatory cytokines. One trial in healthy volunteers found no effect on platelet activation or inflammation markers.
Blood sugar in people
In one small trial, a single dose of bilberry extract reduced post-meal glucose and insulin in men with type 2 diabetes or impaired glucose tolerance. A larger trial of purified anthocyanins found no effect on glucose.
Cholesterol in people
Some human trials found that bilberry or anthocyanin supplements raised HDL cholesterol and lowered LDL cholesterol. Others found no difference between the supplement and placebo groups.
Side effects
The paper reports no serious side effects from bilberry in the studies it looked at. It notes that people taking blood-thinning drugs with high doses of concentrated bilberry extract should be monitored for bleeding.
Animal and lab studies
Animal and lab studies
In animals and lab tests, bilberry extracts protected against oxidative damage, reduced inflammation, lowered blood glucose and improved cholesterol levels. These effects were seen at various doses and in different disease models.
What the authors conclude
“Although there is evidence to support the use of bilberry supplementation as part of a healthy diet, the potential benefits from the use of bilberry supplementation in patients with T2DM or CVD needs to be clarified in large clinical trials.”
Also in their conclusions
- They say that mechanistic studies, animal studies and some clinical trials support the benefits of bilberry supplementation as part of a healthy diet.
- They advise that further studies in well-designed large clinical trials using standardized bilberry extract products are needed to clarify the potential benefits from the use of bilberry supplementation in patients with T2DM or CVD.
- They note that the amount of bilberries consumed and the length of the intervention may be determining factors of the potential effects.
How it was done
Metabolic syndrome raises the risk of heart disease and type 2 diabetes, and oxidative stress and inflammation are thought to play a part. The authors wanted to see whether bilberry, a rich source of antioxidant anthocyanins, could help with these risk factors.
The authors searched PubMed, Web of Science and Google Scholar for studies published from 1991 to 2019 on bilberry, anthocyanins and metabolic or heart risk factors. They found 1034 articles and selected a shortlist of relevant studies, including lab tests, animal studies and human trials.
What it can’t tell you
- Lab and animal results may not carry over to people, because the amounts and mixtures of active compounds can differ.
- Many human trials were small or used different products, so it is hard to compare them or draw firm conclusions.
- The studies cannot show whether bilberry prevents heart disease or diabetes, only how it affects risk factors.
Who paid
- Funding
- Funded by Internal Research Grant of Caritas Institute of Higher Education (from the PubMed record).
- Conflicts
- The authors declare no conflict of interest.
- Authors work at
- Caritas Institute of Higher Education, China; Macau University of Science & Technology, China
The paper
- Title
- Effects of Bilberry Supplementation on Metabolic and Cardiovascular Disease Risk
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Chan SW, Tomlinson B (2020). Effects of Bilberry Supplementation on Metabolic and Cardiovascular Disease Risk. Molecules (Basel, Switzerland). doi:10.3390/molecules25071653Free full textPubMed 32260262DOI
Summary written 29 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error