The Association between Popular Diets and Serum Testosterone among Men in the United States

Purpose: We examined the relationship of the serum testosterone level to low fat, Mediterranean and low carbohydrate diets in a large, nationally representative patient sample. Materials and Methods: We queried the NHANES (National Health and Nutrition Examination Survey) from 1999 to 2000, 2003 to 2004 and 2011 to 2012. Men 18 to 80 years old who completed the 2-day dietary history and underwent serum testosterone testing were included in analysis. Diets were categorized as low fat, Mediterranean, low carbohydrate or nonrestrictive. Multivariable modeling was used to determine the relationship between diet and serum testosterone. Results: Of the 3,128 men who met study inclusion criteria 457 (14.6%) and 764 (24.4%) met the criteria for a low fat and a Mediterranean diet, respectively. Only 2 men (less than 0.1%) met the criteria for a low carbohydrate diet, which was removed from further analysis. Mean +/- SD serum testosterone was 435.5 +/- 6.7 ng/dl. Mean testosterone was lower among men with a low fat diet (410.8 +/- 8.1 vs 443.5 +/- 7.3, p = 0.005) and a Mediterranean diet (412.9 +/- 9.1 vs 443.5 +/- 7.3, p = 0.002). Multivariable analysis controlling for age, body mass index, activity level, diabetes, comorbidities and prostate cancer showed that men with a nonrestrictive diet had higher serum testosterone than those adhering to a low fat diet (beta -57.2, 95% CI -105.6 to -8.8, p <0.05). Conclusions: Men adhering to low fat diets had lower serum testosterone levels even when controlling for comorbidities, age, body mass index and activity levels. As differences in serum testosterone between the diets were modest, the avoidance of fat restrictive diets should be weighed against the potential benefits on an individual basis.