Bilberry (Vaccinium myrtillus) and Cardiovascular / heart health: evidence and sources

Metabolic syndrome is a cluster of interrelated conditions that is associated with an increased risk of cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM). Oxidative stress may impair normal physiological functions, leading to various illnesses. T2DM is considered to be associated with increased oxidative stress, inflammation, and dyslipidemia, which may play a significant role in the development of cardiovascular complications, cancer and vision loss through cataracts and retinopathy. While conventional therapies are a cornerstone for the management of the major risk factors of metabolic syndrome, increasing antioxidant defense by increasing intake of antioxidant-rich foods may improve long term prospects in CVD, obesity and T2DM. Bilberry ( Vaccinium myrtillus L. ) is one of the richest natural sources of anthocyanins which give berries their red/purple/blue coloration. Anthocyanins are powerful antioxidants and are reported to play an important role in the prevention of metabolic disease and CVD as well as cancer and other conditions. This review focuses on the potential effects of bilberry supplementation on metabolic and cardiovascular risk factors. 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.

Bilberries, Vaccinium myrtillus, have a high content of phenolic compounds including anthocyanins, which could provide cardiometabolic health benefits following acute myocardial infarction (AMI). We hypothesized that standard medical therapy supplemented with freeze-dried bilberry after AMI would have a more beneficial effect on cardiovascular risk markers and exercise capacity than medical therapy alone. Patients were allocated in a 1:1 ratio within 24 hours of percutaneous coronary intervention in an 8-week trial either to V myrtillus powder (40 g/d, equivalent to 480 g fresh bilberries) and standard medical therapy or to a control group receiving standard medical therapy alone. High-sensitivity C-reactive protein and exercise capacity measured with the 6-minute walk test were the primary biochemical and clinical end points, respectively. Fifty subjects completed the study. No statistically significant difference in high-sensitivity C-reactive protein was detected between groups. The mean 6-minute walk test distance increased significantly more in the bilberry group compared to the control group: mean difference 38 m at follow-up (95% confidence interval 14-62, P = .003). Ex vivo oxidized low-density lipoprotein was significantly lowered in the bilberry group compared to control, geometric mean ratio 0.80 (95% confidence interval 0.66-0.96, P = .017), whereas total cholesterol and low-density lipoprotein cholesterol did not differ significantly between groups. Anthocyanin-derived metabolites in blood increased significantly in the bilberry group during the intervention and were different after 8 weeks between the bilberry group and control. Findings in the present study suggest that bilberries may have clinically relevant beneficial effects following AMI; a larger, double-blind clinical trial is warranted to confirm this.

The epidemiologic studies from the recent years indicate that high consumption of foods rich in bioactive compounds has a positive effect on human health and could diminish the risk of numerous diseases, such as cancer, heart disease, stroke, Alzheimer's disease, diabetes, cataracts, and even diseases related to age. From all species of fruit, definitely consumption of berries due to its high content of bioactive constituents prevents the risk of cardiovascular disease, oxidative stress and diabetes. The primary phenolic compounds in berries are flavonoids, particularly the anthocyanins. They have potential preventative and therapeutic effects on many diseases such as cancers, inflammation and cardiovascular diseases, obesity, neurodegenerative pathologies, and muscular degeneration. Bilberry fruits have been an important part of local diets in many countries, including Slovakia. They are valued for their pleasant taste and aroma and are often processed into jams, preserves, juices, and alcoholic beverages. In the last two decades, the Saskatoon berry has been cultivated in many parts of the world for its suitability for various food products and due to its high content of nutrients and polyphenols. Cardiovascular disease (CVD) remains the world's leading cause of morbidity and mortality. Dyslipidemia, which results from one or more abnormalities of blood lipids metabolism, remains a major key factor for progression of CVD and leads to the development of atherosclerotic plaques. The aim of this review is to compare and summarize the research evidence on the potential of bilberries and saskatoon berries with an emphasis on recent studies in humans in improving cardiovascular risk factors especially dyslipidemia.

Bilberry ( Vaccinium myrtillus L.) fruits are an important part of local diets in many countries and are used as a medicinal herb to treat various disorders. Extracts from fruits are often a part of eye health-promoting supplements, whereas extracts from leaves are advertised for type 2 diabetes mellitus and glycemic control. This review provides an overview of the current knowledge of the phytochemical contents of bilberry fruits and leaves and their bioactivities, critically summarizes origins of the health claims and the outcome of clinical trials, with special attention towards those published in the past 10 years. Overall, the three most referenced indications, which are type 2 diabetes mellitus, vision disorders and circulatory diseases, all include contradictory results with no clear conclusion as to the benefits and recommended dosages. Moreover, the indications for vision disorders and diabetes originate from unproven or false claims that have been repeated in research since the 20 th century without consistent fact-checking. Beneficial clinical results have been attested for the treatment of dyslipidemia and chronic inflammatory disorders when applied as dietary supplementation of fresh bilberries or as anthocyanin-rich bilberry fruit extracts. However, there is a general lack of double-blinded controlled research with larger sample sizes.

Some epidemiological studies suggest that increased consumption of anthocyanins is associated with lower risk of cardiovascular disease (CVD) and hypertension. Also, high consumption of anthocyanin-rich fruit, such as berries, is associated with a lower risk of developing type 2 diabetes (T2D). In this review, we briefly yet critically assess the available evidence in support of an anti-diabetic role of anthocyanins derived from berries, especially bilberry (Vaccinium myrtillus L., also known as European blueberry, whortleberry, huckleberry and blaeberry) and blueberry (Vaccinium corymbosum, native to the United States). Further, cellular and molecular mechanisms are discussed and the "pharma-nutrition" use of anthocyanin-based preparations for the prevention and treatment of T2D is examined. We conclude that animal and in vitro studies strongly indicate that bilberry and blueberry have the potential to ameliorate T2D and its cardio-metabolic outcomes. However, appropriate clinical trials are lacking and will eventually clarify whether these foods (either as such or formulated as nutraceuticals) might be added to the current pharma-nutritional armamentarium.