Does Tribulus terrestris reduce blood pressure in people with prehypertension? Original paper

Prehypertension (defined as a mean daytime systolic blood pressure of 120–140 mmHg and a diastolic blood pressure of <90 mmHg) increases the risk of developing hypertension and cardiovascular disease. Tribulus terrestris, an Ayurvedic plant, may improve blood pressure in individuals with prehypertension. However, few clinical trials have examined this possibility.

In this 2-month randomized controlled trial, 40 prehypertensive adults (aged 41 years on average) who were not taking antihypertensive medications took capsules containing either 6 grams of Tribulus terrestris dried fruit powder or a placebo.

The primary outcomes were systolic and diastolic blood pressure after 2 months of treatment. The secondary outcomes were systolic and diastolic blood pressure at 2 months of follow-up and adverse events.

As compared to placebo, Tribulus terrestris supplementation improved diastolic blood pressure (from 87 to 82 mmHg), whereas no change was observed with the placebo. Tribulus terrestris supplementation also improved systolic blood pressure (from 132 to 124 mmHg), but this change did not reach statistical significance in the between-group comparisons.

The improvements in systolic and diastolic blood pressure were sustained after 2 months of follow-up. There were no differences in adverse effects between the groups.

Although the results are promising, the researchers did not make adjustments for multiple comparisons, despite measuring two primary outcomes. As such, the findings should be considered exploratory.