Association between dietary total antioxidant capacity and semen quality among men attending an infertility clinic: a cross-sectional study.

Study question: Is dietary non-enzymatic antioxidant capacity related to semen quality?

Summary answer: The only statistically significant association of semen quality parameters with dietary total antioxidant capacity (DTAC) detected was an inverse association between DTAC and ejaculate volume.

What is known already: Growing interest exists regarding the role of diet in influencing semen quality. While DTAC is linked to favorable health outcomes, its association with semen quality, especially among men attending infertility clinics, remains understudied.

Study design size duration: This cross-sectional study was carried out between June and December of 2020. In total, 1715 participants were included in the final analysis.

Participants/materials setting methods: Men who attended an infertility clinic in China were enrolled. Experienced clinical technicians performed the semen analysis. The DTAC indices included the ferric-reducing ability of plasma, oxygen radical absorbance capacity, total reactive antioxidant potential, and Trolox equivalent antioxidant capacity. The quantile regression model was used for multivariate analysis.

Main results and the role of chance: After adjustment for a variety of confounding variables, a significant inverse association was identified between DTAC and ejaculate volume (β_{continuous FRAP} = -0.015, 95% CI = -0.023, -0.006, β_{T3 vs T1} = -0.193, 95% CI = -0.379, -0.006, P_trend = 0.007; β_{continuous TRAP} = -0.019, 95% CI = -0.041, 0.002, β_{T3 vs T1} = -0.291, 95% CI = -0.469, -0.112, P_trend = 0.002). The majority of DTAC indices have no statistically significant association with semen quality parameters.

Limitations reasons for caution: We cannot infer causality because of the nature of the cross-sectional study design. The robustness of the conclusion may be compromised by the exactness of non-enzymatic antioxidant capacity estimation.

Wider implications of the findings: Our findings demonstrated no association between DTAC indices and semen quality parameters among men attending an infertility clinic, except for ejaculate volume. Even though our findings are mostly non-significant, they contribute novel knowledge to the field of study while also laying the groundwork for future well-designed studies.

Study funding/competing interests: This work was supported by the JieBangGuaShuai Project of Liaoning Province [grant number 2021JH1/10400050], the Clinical Research Cultivation Project of Shengjing Hospital [grant number M1590], and the Outstanding Scientific Fund of Shengjing Hospital [grant number M1150]. The sponsors had no role in study design, or in the collection, analysis, and interpretation of data, or in the writing of the report, or in the decision to submit the article for publication. There are no conflicts of interest to declare.

Trial registration number: N/A.