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

Abstract

Intervention with fruit extracts may lower glucose and lipid levels, as well as blood pressure. We reviewed the efficacy of bilberry and grape seed extracts to affect these outcomes across populations with varying health status, age and ethnicity, across intervention doses and durations, in 24 intervention studies with bilberry and blackcurrant (n = 4) and grape seed extract (n = 20). Bilberry and blackcurrant extract lowered average levels of glycated hemoglobin (HbA1c), at least in Chinese subjects, especially in those who were older, who were diagnosed with Type 2 Diabetes Mellitus (T2DM) and who were participating in longer-term studies. We also found good evidence that across studies and in subjects with hypercholesterolemia, T2DM or metabolic syndrome, intervention with bilberry and blackcurrant extract, and to some extent grape seed extract, significantly lowered total and low density lipoprotein (LDL) cholesterol levels after four weeks. Intervention with grape seed extract may reduce systolic and diastolic blood pressure in subjects with hypertension or metabolic syndrome. Differential responsiveness in cholesterol and blood pressure outcomes between stratified populations could not be explained by age, dose or study duration. In conclusion, bilberry and blackcurrant extract appears effective in lowering HbA1c and total and LDL cholesterol, whereas grape seed extract may lower total and LDL cholesterol, and blood pressure, in specific population groups.

Symptomatic hypoglycemia in a nondiabetic adult female recovering from mild COVID‐19 infection: A case report

“…Grape seed extract may improve glucose and cholesterol metabolism. 9 The active component of grape seed extract is proanthocyanidin. 10 Proanthocyanadins have multiple effects on glucose metabolism, which include an improvement of insulin sensitivity, lipid and glucose homeostasis, enzyme inhibition, enhanced hepatic glucose uptake, and hepatic glucose homeostasis.…”

Protective effect of grape seed extract against chronic physical stress‐induced zona fasciculata injury in male rats: Functional, immunohistochemical and electron microscopic study

“…Many recent research studies were done to investigate the possible therapeutic effects of GSE in different pathological conditions (Ali et al, 2015; Kadri et al, 2019; Li et al, 2015; Zhang et al, 2014). Recent literature reported the benefits of GSE against oxidative stress and degenerative diseases including cardiovascular dysfunctions, gastrointestinal distress, neurological disorders, hepatic injuries, neoplastic processes, and carcinogenesis (Abd Eldaim et al, 2021; Ben Youssef et al, 2021; Grohmann et al, 2021; Kadri et al, 2021; Mao et al, 2021; Silvan et al, 2021). However, researches exploring the GSE effects on the adrenal cortex are still very lacking.…”

The Effects of Anthocyanin-Rich Bilberry Extract on Transintestinal Cholesterol Excretion

“…It has been commonly used as a dietary and supplement ingredient to alleviate oxidative stress, inflammation, and ocular health [24]. Bilberry has been reported to have protective effects against oxidative stress, inflammation, hyperglycemia, and lipid metabolism, which are associated with the initiation and progression of CVD [25][26][27][28][29][30][31][32][33]. The effects of bilberry on hypercholesterolemia have been reported in vitro, in vivo in animals, and in clinical trials [33].…”

“…Bilberry has been reported to have protective effects against oxidative stress, inflammation, hyperglycemia, and lipid metabolism, which are associated with the initiation and progression of CVD [25][26][27][28][29][30][31][32][33]. The effects of bilberry on hypercholesterolemia have been reported in vitro, in vivo in animals, and in clinical trials [33]. Bilberry supplementation improved serum cholesterol profiles in high-fat-fed mice, Fischer rats, aging perimenopausal rats, Zucker diabetic fatty rats, and alloxan-induced diabetic rats [34][35][36][37][38].…”