Several studies have shown that Momordica charantia L. (Cucurbitaceae, bitter melon)
has beneficial effects on metabolic syndrome (MetS) parameters and exerts antidiabetic,
anti-hyperlipidemic, and anti-obesity activities. Since the findings of these studies
are contradictory, the goal of this systematic review and meta-analysis was to assess
the efficacy of bitter melon in the treatment of metabolic syndrome, with special
emphasis on the anti-diabetic effect. Embase, Cochrane, PubMed, and Web of Science
databases were searched for randomized controlled human trials (RCTs). The meta-analysis
was reported according to the PRISMA statement. The primary outcomes of the review
are body weight, BMI, fasting blood glucose, glycated hemoglobin A1c, systolic blood
pressure, diastolic blood pressure, serum triglyceride, HDL, LDL, and total cholesterol
levels. Nine studies were included in the meta-analysis with 414 patients in total
and 4–16 weeks of follow-up. In case of the meta-analysis of change scores, no significant
effect could be observed for bitter melon treatment over placebo on fasting blood
glucose level (MD = −0.03; 95% CI: −0.38 to 0.31; I 2 = 34%), HbA1c level (MD = −0.12;
95% CI: −0.35 to 0.11; I 2 = 56%), HDL (MD = −0.04; 95% CI: −0.17 to 0.09; I 2 = 66%),
LDL (MD = −0.10; 95% CI: −0.28 to 0.08; I 2 = 37%), total cholesterol (MD = −0.04;
95% CI: −0.17 to 0.09; I 2 = 66%,), body weight (MD = −1.00; 95% CI: −2.59–0.59; I
2 = 97%), BMI (MD = −0.42; 95% CI: −0.99–0.14; I 2 = 95%), systolic blood pressure
(MD = 1.01; 95% CI: −1.07–3.09; I 2 = 0%) and diastolic blood pressure levels (MD
= 0.24; 95% CI: −1.04–1.53; I 2 = 0%). Momordica treatment was not associated with
a notable change in ALT, AST, and creatinine levels compared to the placebo, which
supports the safety of this plant. However, the power was overall low and the meta-analyzed
studies were also too short to reliably detect long-term metabolic effects. This highlights
the need for additional research into this plant in carefully planned clinical trials
of longer duration.
