Can grape seed extract help patients early-stage high blood pressure?

This study examined if grape seed extract could improve symptoms of early-stage high blood pressure (prehypertension). This study concluded that blood pressure and blood vessel health improved with high doses of the extract.

Hypertension (high blood pressure) and poor blood vessel health can lead to further health complications, such as heart disease. Prehypertension is a precursor to hypertension. It is defined as having a systolic blood pressure (SBP) of 130 – 139 mmHg and/or a diastolic blood pressure (DBP) of 85 – 89 mmHg.

Reactive oxygen species contribute to hypertension. These molecules cause damage to blood vessels and the heart. Antioxidants, often found in plants, break down these molecules and protect cells from damage. Proanthocyanidin is an antioxidant found in grape seeds. Previous studies suggest that grape seed extract can help lower blood pressure. Whether grape seed extract can improve symptoms of prehypertension is unclear.

30 patients with prehypertension were divided into 3 groups. 10 patients received a placebo (a substance with no active effect). 10 patients received a low dose (200 mg/day) of grape seed extract (low dose group). 10 patients received a high dose (400 mg/day) of grape seed extract (high dose group). Blood pressure was measured for 12 weeks.

Overall, the high dose of grape seed extract reduced blood pressure the most. SBP dropped from 148 to 135 mmHg in the high dose group. SBP slightly decreased in the other two groups, from 144 to 142.5 mmHg (low dose) and from 150 to 144 mmHg (placebo). DBP dropped from 96 to 89.9 mmHg in the high dose group compared to 95.9 to 94.3 mmHg (low dose) and 98.4 to 97.1 mmHg (placebo).

The high dose of grape seed extract also improved blood vessel health. Blood vessel stiffness decreased from 28 to 20.6 in the high dose group, compared to the reduction of 25.5 to 21.7 in the low dose group and 23.1 to 19.8 in the placebo group. Distensibility (the ability of blood vessels to be stretched) increased from 6.1 to 8.6 Pa^-1 in the high dose group. The low dose group had an increase from 8.4 to 9.6 Pa^-1, and the placebo group increased from 8.8 to 10 Pa^-1.

Non-smoking participants experienced a greater benefit from grape seed extract. Among participants who received a high dose of the extract, average SBP decreased by 13.1 mmHg and DBP decreased by 6.5 mmHg.

This study concluded that a high dose of grape seed extract helped improve blood pressure and blood vessel health for patients with prehypertension.

This study had a very small number of patients, all of which were Japanese. These results may not apply to all patients. A larger study with a longer follow-up time is needed to confirm these results.