Phytochemical consumption and the risk of teratozoospermia: findings from a hospital-based case–control study in China

Abstract

STUDY QUESTION Are dietary phytochemicals associated with the risk of teratozoospermia? SUMMARY ANSWER Dietary intake of carotene, including total carotene, α-carotene, β-carotene as well as retinol equivalent, and lutein + zeaxanthin, were inversely correlated with the risk of teratozoospermia. WHAT IS KNOWN ALREADY Phytochemicals are natural plant derived bioactive compounds, which have been reported to be potentially associated with male reproductive health. To date, no study has investigated the association between phytochemical intake and the risk of teratozoospermia. STUDY DESIGN, SIZE, DURATION This hospital-based case-control study, which included 146 newly diagnosed teratozoospermia cases and 581 controls with normozoospermia from infertile couples, was conducted in a hospital-based infertility clinic in China, from June 2020 to December 2020. PARTICIPANTS/MATERIALS, SETTING, METHODS Dietary information was collected using a validated semi-quantitative 110-item food frequency questionnaire. Unconditional logistic regression was applied to estimate odds ratios (ORs) and 95% CIs for the associations between phytochemical (i.e., phytosterol, carotene, flavonoid, isoflavone, anthocyanidin, lutein + zeaxanthin, and resveratrol) intake and the risk of teratozoospermia. MAIN RESULTS AND THE ROLE OF CHANCE We observed a decreased risk of teratozoospermia for the highest compared with the lowest tertile consumption of total carotene (OR = 0.40, 95% CI = 0.21-0.77), α-carotene (OR = 0.53, 95% CI = 0.30-0.93), β-carotene (OR = 0.47, 95% CI = 0.25-0.88), retinol equivalent (OR = 0.47, 95% CI = 0.24-0.90), and lutein + zeaxanthin (OR = 0.35, 95% CI = 0.19-0.66), with all of the associations showing evident linear trends (all P trend < 0.05). In addition, significant dose-response associations were observed between campestanol and α-carotene consumption and the risk of teratozoospermia. Moreover, there was a significant multiplicative interaction between BMI and lutein + zeaxanthin intake (P interaction < 0.05). LIMITATIONS, REASONS FOR CAUTION The cases and controls were not a random sample of the entire target population, which could lead to admission rate bias. Nevertheless, the controls were enrolled from the same infertility clinic, which could reduce the bias caused by selection and increase the comparability. Furthermore, our study only included a Chinese population, therefore caution is required regarding generalization of our findings to other populations. WIDER IMPLICATIONS OF THE FINDINGS Dietary phytochemicals, namely carotene, lutein, and zeaxanthin, might exert a positive effect on teratozoospermia. These phytochemicals are common in the daily diet and dietary supplements, and thus may provide a preventive intervention for teratozoospermia. STUDY FUNDING/COMPETING INTEREST(S) : This study was funded by Natural Science Foundation of Liaoning Province (No. 2022-MS-219 to XB Wang), Outstanding Scientific Fund of Shengjing Hospital (No. M1150 to QJ Wu), Clinical Research Cultivation Project of Shengjing hospital (No. M0071 to BC Pan), and JieBangGuaShuai Project of Liaoning Province (No.2021JH1/1040050 to YH Zhao). All authors declare that there is no conflict of interest. TRIAL REGISTRATION NUMBER N/A. WHAT DOES THIS MEAN FOR PATIENTS? Teratozoospermia, a condition which is characterized by the majority of sperm having an abnormal structure, is a common cause of male infertility yet, at present, there is no effective treatment. Available evidence indicates that several physiological, environmental, and genetic factors may cause teratozoospermia, but these factors are difficult to modify. Therefore, the identification of factors that could be changed is important for the prevention of teratozoospermia. Previous studies also report that diet, as a potentially modifiable factor, is correlated to sperm morphology. Phytochemicals are a group of naturally bioactive compounds that exist in multiple plant foods, and they may have effects on sperm quality. However, based on only a few studies, current evidence for an association between dietary phytochemical intake and risk of teratozoospermia is inconclusive. Hence, we performed a large case-control study where we compared 146 men with teratozoospermia to 581 healthy controls with normal sperm. Our results showed that dietary intake of phytochemicals, specifically carotene and lutein + zeaxanthin, was linked to a decreased risk of teratozoospermia. These findings shed some light on the effect of phytochemicals on the development of teratozoospermia. If further studies, also in non-Chinese populations, are carried out and confirm our results, the possibility may then exist to reduce sperm abnormalities in this condition through diet.