To examine the relationship between low-fat, Mediterranean, and low-carbohydrate diets and serum testosterone (T) level using a large, nationally-representative patient sample.

The National Health and Nutrition Examination Survey (NHANES) database was queried from 1999-2000, 2003-2004 and 2011-2012. Men 18-80 years who completed the two-day dietary history and underwent serum T testing were included. Diets were categorized as low-fat, Mediterranean, low-carbohydrate, or non-restrictive. Multivariable modeling was used to determine the relationship between diet and serum T.

Among 3128 men who met inclusion criteria, 457 (14.6%) met criteria for a low-fat diet, 764 (24.4%) a Mediterranean diet, and only 2 (<0.1%) a low-carbohydrate diet, which was removed from further analysis. Mean serum T was 435.5 ± 6.7 ng/dL. Mean T was lower among men with low-fat (410.8±8.1 vs. 443.5±7.3, p=0.005) and Mediterranean diets (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 men with non-restrictive diets had higher serum T compared to those adhering to a low-fat diet (ß -57.2, 95% confidence interval [CI] -105.6 – -8.8, p<0.05).

Men adhering to low-fat diets had lower serum T levels, even when controlling for comorbidities, age, BMI and activity levels. As differences in serum T between diets were modest, the avoidance of fat-restrictive diets should be weighed against the potential benefits on an individual patient basis.

The Journal of urology. 2019 Aug 08 [Epub ahead of print]

Richard J Fantus, Joshua A Halpern, Cecilia Chang, Mary Kate Keeter, Nelson E Bennett, Brian Helfand, Robert E Brannigan

Section of Urology, Department of Surgery, University of Chicago Medicine, Chicago, Illinois., Department of Urology, Northwestern University Feinberg School of Medicine., Department of Surgery, NorthShore University Health System.