Dairy food intake in relation to semen quality and reproductive hormone levels among physically active young men

main results and the role of chance: Total dairy food intake was inversely related to sperm morphology (P-trend ¼ 0.004). This association was mostly driven by intake of full-fat dairy foods. The adjusted difference (95% confidence interval) in normal sperm morphology percent was 23.2% (24.5 to 21.8) between men in the upper half and those in the lower half of full-fat dairy intake (P , 0.0001), while the equivalent contrast for low-fat dairy intake was less pronounced [21.3% (22.7 to 20.07; P ¼ 0.06)]. Full-fat dairy intake was also associated with significantly lower percent progressively motile sperm (P ¼ 0.05). limitations, reasons for caution: As it was a cross-sectional study, causal inference is limited. wider implications of the findings: Further research is needed to prove a causal link between a high consumption of full-fat dairy foods and detrimental effects on semen quality. If verified our findings would mean that intake of full-fat dairy foods should be considered in attempts to explain secular trends in semen quality and that men trying to have children should restrict their intake. study funding/competing interest(s): European Union Seventh Framework Program (Environment), ‘Developmental Effects of Environment on Reproductive Health’ (DEER) grant 212844. Grant P30 DK046200 and Ruth L. Kirschstein National Research Service Award T32 DK007703-16 from the National Institutes of Health. None of the authors has any conflicts of interest to declare.