The effects of olive leaf extract on cardiovascular risk factors in the general adult population: a systematic review and meta-analysis of randomized controlled trials

Systematic review and meta-analysis of randomized controlled trials in adults from the general population, including participants with hypertension, dyslipidemia, obesity, or type 2 diabetes. The review pooled 12 studies and 819 participants across active and placebo-controlled arms.

Olive leaf extract was given orally, most often as tablets or capsules, with two studies using liquids or beverages. Across trials, doses ranged from 500 mg/day to 5 g/day and treatment lasted 6 to 48 weeks, generally compared with placebo.

Olive leaf extract produced modest but favorable effects on blood pressure and lipid measures, with the clearest benefits seen in participants with hypertension and in normal-weight subgroups. Compared with placebo, triglycerides decreased by -9.51 mg/dl (95% CI -17.83 to -1.18; P = 0.025) and systolic blood pressure decreased by -3.86 mmHg (95% CI -6.44 to -1.28; P = 0.003). In hypertensive subgroups, effects were larger for TG (-14.42 mg/dl), TC (-9.14 mg/dl), LDL-C (-4.6 mg/dl), and SBP (-4.81 mmHg); in normal-weight subgroups, TC (-6.69 mg/dl), TG (-9.21 mg/dl), and SBP (-7.05 mmHg) improved. No meaningful changes were found for glucose homeostasis, liver or kidney function, or inflammatory markers.

The evidence base was limited by low-to-very low certainty for several outcomes, heterogeneity in some pooled analyses, and substantial variation in OLE formulation, dose, and duration across studies. Many trials were relatively small and short, and not all outcomes were consistently reported, which limits confidence in the overall estimate of benefit.