Spilanthes acmella supplementation leads to implausible increases in muscle strength Original paper

In this 3-month randomized controlled trial in 546 men (ages 25 to 40), supplementation with Spilanthes acmella (the toothache plant) increased muscle strength, but the effects were so large that it raises doubts about the legitimacy of the findings.

This Study Summary was published on June 5, 2025.

The study

The participants took 500 mg of Spilanthes acmella extract (3.5% spilanthol) or a placebo daily. Half of the participants in each group were assigned to a strength training program.

In the non-strength-training groups, the supplement group had greater increases than the placebo group on their maximum bench press (+39 lb vs. −4.9 lb) and squat (+43 lb vs. −3.6 lb).

In the strength-training groups, the supplement group had greater increases than the placebo group on their maximum bench press ( +112 lb vs. +66 lb) and squat (+198 lb vs. 68 lb).

Reported side effects included taste changes and nausea.

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The results

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    This Study Summary was published on June 5, 2025.

    References

    1. ^Ahtiainen JP, Walker S, Peltonen H, Holviala J, Sillanpää E, Karavirta L, Sallinen J, Mikkola J, Valkeinen H, Mero A, Hulmi JJ, Häkkinen KHeterogeneity in resistance training-induced muscle strength and mass responses in men and women of different agesAge (Dordr).(2016 Feb)
    2. ^Bhasin S, Storer TW, Berman N, Callegari C, Clevenger B, Phillips J, Bunnell TJ, Tricker R, Shirazi A, Casaburi RThe effects of supraphysiologic doses of testosterone on muscle size and strength in normal menN Engl J Med.(1996 Jul 4)
    3. ^Giorgi A, Weatherby RP, Murphy PWMuscular strength, body composition and health responses to the use of testosterone enanthate: a double blind study.J Sci Med Sport.(1999 Dec)
    4. ^Blazevich AJ, Giorgi AEffect of testosterone administration and weight training on muscle architecture.Med Sci Sports Exerc.(2001 Oct)