Study question: Is there any association between the intake of different food groups and the risk of idiopathic asthenozoospermia?
Summary answer: A high intake of processed meat and sweets was positively associated with a higher risk of asthenozoospermia, whereas a high intake of fruits, vegetables, poultry, skim milk and sea foods was associated with a lower risk.
What is known already: A high intake of lipophilic foods like meat products or milk may be negatively associated with semen quality in humans, whereas some fruits or vegetables may maintain or improve semen quality.
Study design, size, duration: A case-control study including 72 asthenozoospermic men and 169 normozoospermic men all from infertile couples who underwent face-to-face private interviews, from January 2011 to December 2011.
Participants/materials, setting, methods: Semen was assessed by volume, sperm concentration, motility and morphology. Usual dietary intakes were assessed using a semi-quantitative food frequency questionnaire. Odds ratios (ORs), 95% confidence intervals (CIs) and evaluation of trends were calculated using logistic regression. The first tertile served as the reference category for regression analyses.
Main results and the role of chance: After adjusting for potential confounders, the risk of asthenozoospermia was significantly higher in the highest tertiles of processed meat (OR: 2.03, 95% CI: 1.70-2.44) and sweets intake (OR: 2.05, 95% CI: 1.09-2.26). Conversely, being in the highest tertile of total fruits and vegetables, the intake of dark green vegetables, skim milk, poultry and sea food intake was associated with a lower risk of asthenozoospermia (P for trend = 0.04, 0.01, 0.02, 0.03 and 0.04, respectively).
Limitations, reasons for caution: Recall bias, selection bias and measurement bias are inevitable in this kind of study and residual confounding due to omission or imprecise measurement of important covariates remains possible.
Wider implications of the findings: Patients with asthenozoospermia should be advised to adhere to a diet rich in fruits, vegetables, poultry, skim milk and sea foods while low in processed meat and sweets.
Study funding/competing interest(s): This study was financially supported by the National Nutrition and Food Technology Research Institute, Faculty of Nutrition and Food Technology, Shahid Beheshti University of Medical Science, Tehran, Iran. No conflict of interests to declare.