Phytochemical consumption and the risk of teratozoospermia: findings from a hospital-based case–control study in China
Authors: Zhao Jun-Qi , Lv Jia-Le , Wang Xiao-Bin , Wei Yi-Fan , Guo Ren-Hao , Leng Xu , Du Qiang , Huang Dong-Hui , Wu Qi-Jun , Pan Bo-Chen , Zhao Yu-Hong 
Published: June 2023

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% confidence intervals (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 &lt;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 &lt;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 INTERESTS
This study was funded by Natural Science Foundation of Liaoning Province (No. 2022-MS-219 to X.B.W.), Outstanding Scientific Fund of Shengjing Hospital (No. M1150 to Q.J.W.), Clinical Research Cultivation Project of Shengjing Hospital (No. M0071 to B.C.P.), and JieBangGuaShuai Project of Liaoning Province (No. 2021JH1/1040050 to Y.H.Z.). All authors declared that there was no conflict of interest.

TRIAL REGISTRATION NUMBER
N/A.