The study was a review and meta-analysis combining the results of six controlled studies
Low fat diets decrease men’s testosterone levels by 10-15%, according to a study conducted at the University of Worcester and published in The Journal of Steroid Biochemistry and Molecular Biology.
Low testosterone levels are reportedly linked to a higher risk of heart disease, diabetes, and Alzheimer’s disease. Testosterone levels also have an impact on men’s athletic performance along with their mental and sexual health. Low risk dietary strategies could be a useful treatment for low testosterone.
The study was a review and meta-analysis, which combined the results of six controlled studies with a total of 206 participants. The studies first put men on a high fat diet (40% fat), and then transferred them to a low fat diet (20% fat), and found their testosterone levels decreased by 10-15% on average. Particularly significant were vegetarian low fat diets causing decreases in testosterone up to 26%.
The authors linked the results to similar studies conducted in humans and mice. These studies found high intakes of monounsaturated fats found in olive oil, avocados, and nuts may boost testosterone production. However, omega 6 polyunsaturated fats predominantly found in vegetable oils, may damage the cells’ ability to produce testosterone. This is because highly unsaturated fats such as polyunsaturated fats are more prone to oxidation, which causes cell damage.
The authors say further research needs to be done in this area. Lead researcher Joseph Whittaker said: “Ideally, we would like to see a few more studies to confirm our results. However, these studies may never come, normally researchers want to find new results, not replicate old ones. In the meantime, men with low testosterone would be wise to avoid low fat diets”.
Traditionally dietary guidelines have focused on limiting fat intake, with the current UK and US guidelines limiting fat intake to less than 35% of total calories. However, as more research on the benefits of high fat, low carbohydrate diets is done, the researchers say, this traditional view is coming under increasing scrutiny.