Low Fat, Mediterranean Diets Linked to Low Testosterone in Men

A new analysis of more than 3000 participants from a nationwide health study is revealing more about how a male patient’s diet can play a role in their testosterone levels.

Results of the study suggested patients adhering to low fat or Mediterranean diets were more likely to have low serum testosterone levels than patients with a nonrestrictive diet.

To assess the impact of various diets on serum testosterone levels, investigators conducted an analysis of 3128 men from the National Health and Nutrition Examination Survey (NHANES). To be eligible for inclusion, participants needed to be between the ages of 18 and 80 years, have undergone serum testosterone testing, and have complete full 2-day dietary history data.

Investigators classified diets into 3 categories: low fat, Mediterranean, and low carbohydrate diets. The primary outcome of the study was the impact of diet on total serum testosterone level and secondary outcome was serum testosterone dropping below a threshold of 300 ng/dl, which is the American Urological Association’s cutoff for testosterone deficiency. Investigators noted multivariable modeling was to evaluate potential relationships between a patient’s diet and serum testosterone levels.

Of the 3128 included in the analysis, 2156 had diets that did not meet the investigators’ criteria for a restrictive diet. Among the 973 who met the criteria for a restrictive diet, 764 adhered to a Mediterranean diet, 457 adhered to a low fat diet, and 2 adhered to a low carbohydrate diet—due to the low number of participants classified as having a low carbohydrate diet, this group was excluded from the analyses.

Overall, the mean serum testosterone level of the cohort was 435.5±6.72 ng/dl and 26.8% were classified as having low serum testosterone. When examining the relationship between diet and serum testosterone, univariable analyses revealed men on a low fat (410.81±11.34 versus 443.47±7.31 ng/dl, P=0.002) and Mediterranean (412.90±9.19 versus 443.47±7.31 ng/dl, P=0.005) diet had lower levels than men on a nonrestrictive diet.

Multivariable analyses indicated similar results in regard to men with low fat diets and lower serum testosterone levels compared to nonrestrictive diets (ß —57.22; 95% CI –105.60 to –8.83, P=0.02) and Mediterranean diets were associated with lower serum testosterone levels compared to a nonrestrictive diet, but this did not reach statistical significance (ß —26.15; 95% CI –61.92–9.62, P=0.15).

Investigators noted a multitude of limitations in their study. Limitations included the inability to account for potential longitudinal changes in diet, serum testosterone, and other comorbidities due to the cross-sectional dataset, dietary intake was self-reported, and serum testosterone was only measured once. Other limitations included subject to diet adherence was assumed based on subject recall, men in the later, less restrictive phase of a ketogenic diet were not captured in the analysis, and the study may not have been able to account for all potential confounding factors.

This study, titled “The Association between Popular Diets and Serum Testosterone among Men in the United States,” was published in The Journal of Urology, the Official Journal of the American Urological Society.