Grape seed extract has mixed CV effects
MedWire News: Grape seed extract has varied effects on markers of cardiovascular (CV) risk, a study shows.
Use of grape seed extract reduces systolic blood pressure and heart rate, but has no effect on lipid levels or inflammation, report Craig Coleman (University of Connecticut, Hartford, USA) and colleagues in the Journal of the American Dietetic Association.
Grape seed extract has been studied previously because it contains a high concentration of proanthocyanidins, a class of polyphenol flavonoid complexes, explain the researchers.
Flavonoids, which are found in red wine, have been shown to be inversely correlated with death from coronary heart disease. In addition, grape seed extract is known to have antioxidant properties, and some trials have suggested it might have beneficial effects on the CV system, they say.
In the present study, Coleman and colleagues performed a meta-analysis of nine randomized clinical trials to assess the effect of grape seed extract on various CV risk markers.
Among the 390 patients included in the analysis, individuals were treated with various doses of grape seed extract, ranging from 200 mg to 1000 mg per day.
Follow-up ranged from 2 to 24 weeks, and the majority of trials evaluated patients with one or more CV risk factors, such as Type 2 diabetes, the metabolic syndrome, or hypercholesterolemia.
The grape seed interventions significantly lowered systolic blood pressure by a weighted mean of 1.54 mmHg and heart rate by a weighted mean of 1.42 beats per minute.
However, no significant change in diastolic blood pressure, lipids, and C-reactive protein levels was observed among the treated patients.
The researchers note that the effect of grape seed extract on systolic blood pressure is "very modest in comparison to reductions seen with prescription antihypertensive drugs."
Still, they say the modest reduction would translate into benefits at the population level.
For example, it is estimated that a 3-mmHg reduction in systolic blood pressure could reduce risk for mortality by 4%, mortality after stroke by 8%, and mortality after coronary artery disease by 5%, they state.
Based on these data, Coleman et al conclude that the antihypertensive effects of grape seed extract should be studied in larger randomized clinical trials of longer duration, such as those with increased risk for CV disease, including hypertension patients.
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