Nutritional Geometry of Male Fertility: Moving Beyond The ‘High-Fat’ Diet

Abstract

Background: Females are given extensive dietary recommendations both during and prior to pregnancy, but similar guidelines for males trying to conceive are conspicuously absent. There is an urgent need to fill this knowledge gap because male fertility is in decline, with rising rates of obesity likely to be a contributing factor. Yet, we understand surprisingly little about nutritional impacts on male fertility. Aim: To examine the individual and interactive effects of protein, carbohydrates, and fats on male reproductive traits, we conducted a nutritional geometry study in adolescent C57Bl6 male mice. Method: Mice were fed one of ten isocaloric diets differing only in macronutrient balance (n = 6/diet) from 5 to 20 weeks of age. Reproductive organs were fixed/frozen and processed for a range of fertility-related measures. Results: We found that different aspects of reproductive function were influenced by different macronutrients. Testis mass and expression of HSD17B3 (testosterone biosynthesis) were positively related to the proportion of protein in the diet. In contrast, dietary fat had a stronger influence on male body mass and seminal vesicle mass. Both dietary protein and fat were found to influence testicular expression of genes with antioxidant functions (GSS, GPX1, GPX4). The number of seminiferous tubules and degree of vacuolation within seminiferous tubules were influenced by complex interactive effects between macronutrients. Conclusion: This foundational study suggests that a far more nuanced approach is required to develop pre-conception dietary recommendations for males, and reveals exciting new directions for research.