The effect of bilberry on cardiovascular risk factor in type 2 diabetes mellitus subjects

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The effect of bilberry on cardiovascular risk factor in type 2 diabetes mellitus subjects


Author: Cheung, Ching-man Sabrina
Title: The effect of bilberry on cardiovascular risk factor in type 2 diabetes mellitus subjects
Degree: M.Sc.
Year: 2009
Subject: Hong Kong Polytechnic University -- Dissertations.
Bilberry -- Therapeutic use.
Cardiovascular system -- Diseases -- Treatment.
Diabetes -- Treatment.
Department: Dept. of Health Technology and Informatics
Pages: xv, 164 leaves : ill. (some col.) ; 30 cm.
Language: English
Abstract: Introduction: Berries are an important dietary source of antioxidant phenolic compounds, and anthocyanins are the most abundant type of antioxidant in berries, especially in bilberry (Vaccinium myrtillus L.). Recent studies indicate that anthocyanins have a positive effect on Type 2 DM and CVD risk through a wide range of reported biological effects, including antioxidant, anti-inflammatory, hypoglycaemic and vasodilatory effects. However, study of potential beneficial effects of bilberry in relation to the important area of improving control of hyperglycaemia and lowering CVD risk in Type 2 DM patients is lacking. Therefore, it is of interest to investigate the effect of bilberry supplementation on glycaemic control and CVD risk in a controlled human intervention trial with a group of Type 2 DM patients by the use of a biomarker approach. Aims: The main aim of this part of a wider study was to investigate the supplementation-related changes in selected cardiovascular disease risk biomarkers in type 2 diabetic subjects supplemented with bilberry extract for 4 weeks. A second aim was to compare the baseline concentrations of cardiovascular risk biomarkers in type 2 diabetes patients with age and sex matched normal subjects of the same (Hong Kong Chinese) ethnicity. Methods: This was a randomized, double-blinded, placebo-controlled intervention study of cross-over design. Thirteen type 2 diabetic patients1, with no record of serious illness other than diabetes and an entry body mass index (BMI) >23 kg/m2, were recruited from the diabetic and general medical clinics of the Prince of Wales Hospital with their informed consent. They were assigned on a non selective basis to receive bilberry or placebo capsules (2 twice per day) for 4 weeks. After a 6 weeks' wash out period, they were crossed over onto the other treatment (bilberry or placebo capsules, different to previous treatment) for 4 weeks. Pre- and post- treatment fasting venous blood samples were collected for each treatment, and biomarkers of glycaemic control (fasting plasma glucose and HbAlc) and cardiovascular disease risk (lipid profile, hsCRP, IL-6, uric acid and sVCAM-1 in fasting plasma) were measured. In addition, results for biomarkers of interest from 25 age- and sex-matched apparently healthy fasting subjects were collected from a database of our Antioxidant Research Group and the results were used for comparison with the baseline of corresponding biomarkers of the type 2 diabetic patients in this study. Results: After 4 weeks' bilberry supplementation, a significant reduction (P<0.005) of HbAlc (from 7.7% to 7.2%) was seen in type 2 diabetic subjects when compared to placebo treatment. Other CVD risk biomarkers of lipid profile, IL-6, hsCRP, sVCAM-1 and UA did not change during the study. In addition, the concentration of total cholesterol (P<0.01) and LDL-C (P=0.057) in plasma of diabetic subjects (CHOL=4.7mmol/L, LDL-C=2.5mmol/L) was lower than that of normal subjects (CHOL=5.6mmol/L, LDL-C=3.1mmol/L). Conclusions: The result of this preliminary study suggested bilberry extract supplementation may modulate HbAlc in type 2 diabetic subjects; this may be beneficial for the management of type 2 diabetes. Diabetic patients under monitoring by a diabetic centre were shown to have lower total cholesterol level and LDL-C than normal subjects, suggesting that dietary advice received by the diabetic subjects as part of their treatment is successful, but results indicate also that many apparently healthy subjects in Hong Kong may have high CVD risk and follow unhealthy diets.

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