Background

    Most men experience reductions in testosterone as they age. Eurycoma longifolia (EL), an herb sometimes used as an aphrodisiac, has been hypothesized to increase testosterone levels.

    The study

    This 12-week randomized controlled trial assessed the effects of an EL extract on testosterone levels and quality of life in men. The participants — 105 men, 50-70 years of age, with testosterone levels of less than 300 ng/dL and BMI between 18 and 30.0 — took 100 mg of EL, 200 mg of EL, or a placebo daily for 12 weeks. The investigators assessed the following outcomes:

    • Total testosterone (TT)
    • Free testosterone (FT)
    • Sex hormone-binding globulin (SHBG)
    • DHEA
    • HbA1C
    • Insulin-like growth factor-1 (IGF-1)
    • Thyroid hormones
    • Cortisol
    • Aging male symptoms (AMS) score
    • Fatigue severity scale (FSS)
    • Muscle strength, assessed via back-leg-chest dynamometer

    The results

    TT was higher at week 12 in the 100 mg EL group and at weeks 4, 8, and 12 in the 200 mg EL group, compared to placebo. There were no differences between groups in FT at any time point, but the 100 mg EL group experienced significant within-group increases at weeks 4, 8, and 12, and the 200 mg EL group experienced within-group increases at weeks 2, 4, 8, and 12.

    AMS and FSS scores were higher at weeks 2, 4, 8, and 12 in both EL groups. Free T3 (a thyroid hormone) was higher at baseline and at the end of the study in the 100 mg EL group than in the placebo group, and muscle strength was higher at the end of the study in the 200 EL mg group than the placebo group.

    Note

    The company that formulated the supplement (Biotropics Malaysia) funded the study. Additionally, two of the study authors are employees of Biotropics Malaysia.

    While statistically significant, the increases in total testosterone (+25 ng/dL from baseline to the end of the study in the 200 mg EL group) were not clinically significant.

    The body of literature as a whole does not support the use of EL to increase testosterone.

    This Study Summary was published on September 1, 2021.