Efficacy of Bilberry and Grape Seed Extract Supplement Interventions to Improve Glucose and Cholesterol Metabolism and Blood Pressure in Different Populations-A Systematic Review of the Literature

MDPI (Multidisciplinary Digital Publishing Institute)
Abstract: Previous studies found that intervention with fruit extracts rich in flavonoids can de-crease levels of blood glucose, cholesterol, and blood pressure. In this study we set out to critical-ly review the efficacy by which bilberry and grape seed extracts affect these outcomes, and whether factors such as health status, age, intervention dose and duration may affect respon-siveness. Through a systematic literature search we identified 22 eligible intervention studies, 4 with bilberry and 18 with grape seed extract. We found that bilberry extract lowered average lev-els of HbA1c by 4.7% in an older Chinese population diagnosed with T2DM. Additionally, chronic interventions had a larger impact on glucose metabolism markers compared to short-term interventions. Interventions with both grape seed and bilberry extracts lowered total and LDL cholesterol levels by up to 4 and 10%, respectively, irrespective of the participants' health condition and other study characteristics. Intervention with grape seed extract also led to significant reductions in systolic and diastolic blood pressure of 5% and 4%, respectively, in hy-pertensive subjects, but also in healthy individuals and those diagnosed with metabolic syn-drome. In conclusion bilberry extract appears to lower blood glucose, while grape seed extract could be considered a potential substitute for blood pressure drugs in mild hypertension. We observed that the responsiveness to the treatments could be dependent on pre-existing health conditions, and chronic interventions appear to be more beneficial for blood glucose metabolism in comparison to short-term interventions. (currently 255 words, should be 200 words)
Refereed journal
Output Tags
WP 3.2 Healthy diets and dietary choice (RESAS 2016-21)