Chilli boosting testosterone in rats by how many

1. The basic finding: rodents showed higher testosterone after capsaicin exposure

Multiple summaries and some primary animal papers report that experimental exposure to capsaicin led to increased testosterone or altered testicular physiology in rodents. Media pieces and a PubMed-indexed article note that capsaicin “appears to enhance testicular cell proliferation and can affect the release of … testosterone” and that serum testosterone rose in pubertal and adult rats/mice fed capsaicin ^{[1] [2]}. Secondary write-ups repeat the statement that rodents given capsaicin showed increased gonadal testosterone production ^{[5] [6]}.

2. How strong are the animal results — and what exactly was measured?

Available sources describe increased serum testosterone and changes in testis morphology or ghrelin expression after capsaicin exposure ^{[1] [2]}. They do not, in the provided coverage, give a single consolidated effect-size number (e.g., “X% increase”) or the full experimental protocol and sample sizes needed for quantitative comparison; reporting summarizes that levels “increased” or that production “significantly increased” in adolescent and adult rodents ^{[1] [5]}. Therefore, the precise magnitude by which testosterone rose in those rodent studies is not provided in the supplied reporting (not found in current reporting).

3. Human evidence points to correlation, not causation

The human study from Grenoble measured endogenous salivary testosterone in 114 men and found that men with higher testosterone voluntarily used more hot sauce in a lab task — a correlation between preference and baseline testosterone ^{[3] [4]}. Multiple outlets caution that correlation does not equal causation and that the human study did not measure whether eating chili raises testosterone in people ^{[7] [8]}. Some outlets explicitly state that the boosting effect has “only been shown to work in rodents so far” ^[8].

4. Possible alternative explanations and confounders

Commentary in the coverage offers alternative explanations: men with higher testosterone might be more willing to take sensory risks or to “show off” by tolerating heat, cultural associations of masculinity could influence consumption, and color preferences (red sauce) or learned desensitization to capsaicin might explain behaviour rather than a hormonal effect of the food itself ^{[7] [9] [4]}. The human study authors and science commentators emphasize those behavioral and cultural confounders ^{[7] [4]}.

5. Media amplification and repeated phrasing

Several news outlets translated the rodent observations into headlines implying that chili “boosts testosterone,” sometimes without the important caveat that that effect was only shown in animals ^{[10] [11] [12]}. Other outlets maintained the caveat; The Local and ScienceAlert explicitly remind readers that direct boosting of human testosterone by spicy food has not been demonstrated ^{[8] [7]}. The disparity shows how preliminary animal findings can be framed as human benefits in popular coverage ^{[10] [6]}.

6. What this means if your question is “by how many?”

The sources provided do not include a clear numerical effect size for the increase in rodent testosterone that would let us answer “by how many” precisely; summaries say “increased” or “significantly increased” but omit exact percent or ng/dL figures in the cited reporting (not found in current reporting). For humans, the available study does not report an experiment of chili ingestion raising testosterone, so there is no human effect-size to cite ^{[3] [7] [8]}.

7. Bottom line and recommended caution

There is consistent reporting that capsaicin exposure raised testosterone-related measures in rodents and that human observational data link higher baseline testosterone with preference for spicy food ^{[1] [2] [3]}. However, available sources do not provide the numeric magnitude of the rodent increase in the material you supplied, nor do they show that eating chili raises testosterone in people — the human data only show correlation and not causation ^{[3] [7] [8]}. Further reading of the original rodent papers (full texts, methods, and numeric results) would be required to quantify “by how many.”