Blackmores Institute

Fifty studies were included in the meta-analysis with data pooled using a random-effects model and the weighted mean difference (WMD) considered as the overall effect size.
 
 “Pooling effect sizes from studies demonstrated a significant decrease in:
 • Fasting plasma glucose (FPG; WMD): −2.01; 95% confidence interval (CI): −3.14, −0.86)
 • Total cholesterol (TC; WMD: −6.03; 95% CI: −9.71, −2.35) 
 • Low-density lipoprotein (LDL) cholesterol (WMD: −4.97; 95% CI: −8.37, −1.57)
 • Triglycerides (WMD: −6.55; 95% CI: −9.28, −3.83), and 
 • C-reactive protein (CRP) concentrations (WMD: −0.81; 95% CI: −1.25, −0.38) 
 following that grape seed extract (GSE) therapy,” the authors reported.
 
 With dyslipidaemia, particularly elevated plasma low-density lipoprotein (LDL) cholesterol levels and metabolic syndrome (MetS) considered among the most important risk factor for cardiovascular disease and; GSE with its high flavonoid content and beneficial effects on health, the meta-analysis was performed to evaluate the effect of GSE administration on glycaemic control, serum lipoproteins, CRP levels, and obesity as defined by anthropometric parameters.
 
 “Studies have reported that grape seed polyphenols had a beneficial effect on metabolic abnormalities in patients with and without MetS however results were not conclusive, however, the current meta-analysis showed that GSE intake significantly reduced FPG, TC, LDL cholesterol, triglycerides, and CRP levels, but did not affect haemoglobin A1C (HbA1c); high density lipoprotein cholesterol (HDL) levels, and anthropometric measurements,” the authors stated.
 
 According to the review the beneficial effects of grape seed on total cholesterol and low-density lipoprotein cholesterol levels may be due to inhibiting intestinal cholesterol absorption.
 
 “However, it is most likely that the primary beneficial effect of grape seed occurs due to mechanisms other than just decrease of plasma lipoproteins concentrations, including scavenging of hydroxyl and peroxyl radicals, antioxidant activities, and suppressing of the oxidation of LDL.”
 
 Although discrepancies between different studies might be explained by the different dosages of grape seed used, different durations of interventions, the quality of grape seed used or the different characteristics of study participants, the authors of the study acknowledged the beneficial effect of grape seed polyphenols on metabolic abnormalities in people with and without MetS.
 
 ‘This meta-analysis demonstrated that grape seed extract significantly reduced fasting plasma glucose, total cholesterol, low density lipoprotein cholesterol and C-reactive protein levels,” the authors concluded.
 
 
 Source:
 Phytotherapy Research 2019; 1-15 doi: <a href="https://doi.org/10.1002/ptr.6518">10.1002/per.6518</a>

The humble grape seed may deserve more attention with a systematic review finding that grape seed extract significantly reduced fasting plasma glucose, total cholesterol, low density lipoprotein cholesterol and C-reactive protein levels.

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