Association of plant-based diets with odds of teratozoospermia in China: A case-control study

• Overall plant-based diet index (PDI), especially the healthful PDI, may be important for the prevention of teratozoospermia. • Unhealthful PDI was positively associated with teratozoospermia in younger participants. • An additive interaction was detected between age and unhealthful PDI. Previous research showed that plant-based diets were correlated with male-productive health, but evidence regarding the association of this diet with teratozoospermia remains unclear. This study aimed to investigate the association between plant-based diets and teratozoospermia odds. We conducted a case-control study involving 146 patients with teratozoospermia and 581 healthy controls in the infertility clinics of the Center for Reproductive Medicine during June and December 2020. To evaluate dietary data for the included participants, a validated food frequency questionnaire was utilized. Odds ratios (ORs) and 95% confidence intervals (CIs) for the development of teratozoospermia related to the plant-based diets were employed using unconditional logistic regression. Higher adherence to the overall plant-based diet index (PDI) was inversely associated with the odds of teratozoospermia (OR T3 vs. T1 = 0.56; 95 % CI = 0.33–0.94). Additionally, greater adherence to the healthful PDI (hPDI) was correlated with a lower odds of teratozoospermia (OR T3 vs. T1 = 0.56; 95 % CI = 0.34–0.90), whereas the null association of unhealthful PDI (uPDI) with teratozoospermia was observed (OR T3 vs. T1 = 1.15; 95 % CI = 0.70–1.91). Interestingly, uPDI was positively associated with the odds of teratozoospermia among men with age < 32 years (OR T3 vs. T1 = 2.80; 95 % CI = 1.23–6.58). Of note, an additive interaction between age and uPDI on the odds of teratozoospermia was also detected. Our findings indicate that overall plant-based diets, especially the healthful plant-based diets, may be important for the prevention of teratozoospermia.