Low-fat diet linked with lower testosterone level

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Results of a cross-sectional study of adult American men show that adherence to a low-fat diet is associated with a lower serum testosterone level.

The implications of the findings for patient care, however, must take into account the limitations of the study and the effects of a low-fat diet on overall health, according to the investigators.

The research was recently published in the Journal of Urology (2020; 203:398-404). Study author Joshua A. Halpern, MD, MS, told Urology Times, “On the one hand, our study provides compelling evidence that a fat-restricted diet is associated with mildly decreased testosterone levels, regardless of body mass index. On the other hand, caution should be used when interpreting the results and applying them for counseling men with low testosterone considering that the potential benefits of fat-restricted diets, which could include improvement in lipid profiles and optimization of cardiovascular health, could outweigh the decrease in serum testosterone they may experience.

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“In addition, it is important to recognize that our study did not track the longitudinal impact of diet on testosterone. Rather, due to the cross-sectional nature of our study, the associations we identified between diet and serum testosterone are merely a snapshot from one point in time,” added Dr. Halpern, assistant professor of urology at Northwestern University Feinberg School of Medicine, Chicago.

“Some prior studies examining the effects of popular diets upon weight loss reported that weight loss can lead to increases in serum testosterone, but there have not been studies examining the direct effect of diet on testosterone levels,” lead author Richard J. Fantus, MD, told Urology Times. “Our investigation is the first to use a large, population-based cohort to understand the association between some of the most popular diets and serum testosterone.

“Our recommendation is that dietary advice should be personalized for each patient and their specific health goals, rather than use a ‘one-size-fits-all’ approach. We hope that our research will enable both physicians and patients to make more educated decisions in pursuing an individualized approach,” added Dr. Fantus, a urology resident at the University of Chicago Medicine.

To examine the relationship between serum testosterone and diet, the authors extracted data collected in three National Health and Nutrition Examination Surveys from adult men (ages 18 to 80 years) who completed the 2-day dietary history and underwent serum testosterone. Their analysis included 3,128 men.

Based on Dietary Intervention Randomized Controlled Trial group criteria, 457 men (14.6%) were identified as following a low-fat diet and 764 men (24.4%) were identified as following a Mediterranean diet. Less than 1% of the cohort were following a low-carbohydrate diet, and no additional analyses were done for that subgroup.

Next: Association observed on multivariable analysisAssociation observed on multivariable analysis

Mean serum testosterone in men on a low-fat diet was significantly lower than in men on a nonrestrictive diet (410.8 vs. 443.47 ng/dL; p=.002). On multivariable analysis controlling for a number of potential confounders, serum testosterone level remained significantly lower in the low-fat diet group compared with the men on nonrestrictive diets (p<.05).

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Mean serum testosterone for the men adhering to a Mediterranean diet was 412.90 ng/dL and significantly lower than in the group on a nonrestrictive diet in univariable analysis (p=.005), but the statistical difference between groups was not maintained on multivariable analysis.

The study also compared the diet groups for the proportion of men with serum testosterone <300 ng/dL, representing the AUA cutoff for low testosterone. The analyses found no statistically significant differences comparing either the low-fat diet or the Mediterranean diet groups to the nonrestrictive diet group.