Herbal blend claims a testosterone boost — by its maker

Supplements marketed as adaptogenic or androgen-supportive are a large and growing category, promising more strength, more endurance and better hormonal health without a prescription. Most such products are sold on the back of animal data or mechanistic reasoning rather than controlled human trials, so a paper that runs both a preclinical and a clinical arm on the same formulation is at least attempting the harder standard. The question this work set out to answer is whether a proprietary herbal blend, NS2128E03, is safe and whether any hormonal effects seen in rodents actually appear in training humans. Understanding who ran the study matters as much as what it reports.

The preclinical arm gave Sprague Dawley rats oral NS2128E03 at low and high doses for 50 days, assessing toxicity, sexual behaviour indices such as mount frequency, intromission latency and ejaculatory latency, hormonal changes and endurance, with histopathology of the reproductive organs. The clinical arm was described as a randomised, double-blind, placebo-controlled trial in healthy adult males taking NS2128E03 or placebo for 60 days alongside resistance training. Outcomes included muscle performance measured by cable pulldown and mid upper arm circumference, treadmill endurance, serum testosterone and safety laboratory measures. Recovery biomarkers mTOR, lactate dehydrogenase and creatine kinase were also tracked. The authors are affiliated with the company that produces the formulation.

In rats, the blend significantly increased total and free testosterone, improved the sexual behaviour indices measured, and enhanced physical endurance without adverse effects, with normal reproductive organ architecture on histopathology. In the human trial, the authors report statistically significant improvements versus placebo in bench press, leg press and handgrip strength, treadmill endurance, and both total and free testosterone. Recovery biomarkers changed significantly (P < 0.01), with mTOR increased and lactate dehydrogenase and creatine kinase reduced. No adverse events or clinically meaningful laboratory abnormalities were reported. Notably, the abstract reports no participant numbers, no baseline values and no magnitudes for any of the human outcomes, and the strength tests listed in the results do not fully match the outcomes listed in the methods.

Rodent hormonal responses to botanical extracts translate to humans inconsistently, so the preclinical arm is supportive at best rather than confirmatory. A placebo-controlled design alongside a training programme is the right shape of study, but without sample size, effect magnitude or independent oversight the human findings cannot be weighed against the wider literature on testosterone-supportive supplements, which is characterised by small trials and frequent commercial sponsorship. The mismatch between the stated methods and the reported strength outcomes is an additional reason for caution. Open questions include how large the changes actually were, whether testosterone shifts stayed within normal physiological range, and whether an independent group can reproduce any of it.

This is a manufacturer's own evidence package for its own product, and it should be read in that light rather than as neutral science. The rodent work suggests a plausible hormonal signal worth testing properly, and the reported absence of adverse events is mildly reassuring, but reassurance from a self-funded study is weak reassurance. Because no numbers accompany the human results, there is no way to judge whether any improvement would be noticeable in a gym or merely statistically detectable. The resistance training itself is the part of this protocol with well-established effects on strength and endurance.