Phytoestrogen intake and other dietary risk factors for low motile sperm count and poor sperm morphology

Abstract

Background Few potentially modifiable risk factors of male infertility have been identified, and while different diets and food groups have been associated with male infertility, evidence linking dietary factors including phytoestrogens and semen quality is limited and contradictory. Objectives To study the associations between phytoestrogen intake and other dietary factors and semen quality. Materials and Methods A case‐referent study was undertaken of the male partners, of couples attempting conception with unprotected intercourse for 12 months or more without success, recruited from 14 UK assisted reproduction clinics. A total of 1907 participants completed occupational, lifestyle and dietary questionnaires before semen quality (concentration, motility and morphology) were assessed. Food intake was estimated by a 65‐item food frequency questionnaire (FFQ) covering the 12 months prior to recruitment. Analyses of dietary risk factors for low motile sperm concentration (MSC: <4.8 × 106/mL) and poor sperm morphology (PM: <4% normal morphology) used unconditional logistic regression, accounting for clustering of subjects within the clinics, first without, and then with, adjustment for confounders associated with that outcome. Results High consumption of daidzein (≥13.74 μg/d), a phytoestrogen found in soy products, was a protective factor for MSC with an odds ratio (95%CI) of 0.58 (0.42‐0.82) after adjustment for clustering and potential confounding. Dietary risk factors for PM after similar adjustment showed that drinking whole milk (OR 0.67, 95%CI 0.47‐0.96) and eating red meat were protective with an OR 0.67 (0.46‐0.99) for eating red meat >3 times/wk. Discussion In this case‐referent study of men attending an infertility clinic for fertility diagnosis, we have identified that low MSC is inversely associated with daidzein intake. In contrast, daidzein intake was not associated with PM but eating red milk and drinking whole milk were protective. Conclusions Dietary factors associated with semen quality were identified, suggesting that male fertility might be improved by dietary changes.

Neither soyfoods nor isoflavones warrant classification as endocrine disruptors: a technical review of the observational and clinical data

“…Finally, there is a case-referent study involving the male partners of couples attempting conception with unprotected intercourse for 12 months or more without success, recruited from 14 UK assisted reproduction clinics (Povey et al 2020). Food intake was estimated by a 65-item food frequency questionnaire (FFQ) covering the 12 months prior to recruitment.…”

Improved Food-Processing Techniques to Reduce Isoflavones in Soy-Based Foodstuffs

“…In addition, five clinical or population studies have so far reported the association of high soy IFs intake and their biomarkers in body fluids with a reduction in sperm count and quality [ 11 , 12 , 13 , 14 , 15 ]. When studies reported no effects on semen quality in men, it was at low doses [ 16 ] or for too short exposure times [ 17 ]. Overconsumption of soy has also been linked to several adverse clinical cases in women [ 18 ] and men [ 19 ].…”

Phytoestrogens and Health Effects

“…Currently, in men, five population studies linked a decrease in sperm count and quality to high isoflavones intakes (>40 mg/day) and high isoflavones levels in biological fluids [ 217 , 243 , 244 , 245 , 246 ]. Conversely, intervention studies did not show any effect, but either the time of exposure was too short [ 247 ] or the dose of exposure was below the efficient intake [ 248 ]. In American women, high isoflavone exposure (>50 mg/day) was shown to increase the occurrence of luteal-phase deficiencies that can delay conception [ 249 ] and was also shown to increase the risk of being nulliparous at the age of 26 or at menopause [ 64 ].…”