Table_1_The Association Between Dairy Product Consumption and Asthenozoospermia Risk: A Hospital-Based Case-Control Study.DOCX

Background: Evidence of an association between dairy product and main related dairy nutrient intake, and the asthenozoospermia risk have been limited and controversial.
Methods: A hospital-based case-control study including 549 men with asthenozoospermia and 581 normozoospermic controls was carried out in the infertility clinics of Shengjing Hospital of China Medical University between June, 2020 and December, 2020. Dietary intake was assessed with a validated food frequency questionnaire. According to the World Health Organization guidelines, semen parameters were collected through masturbation and were measured with WLJY9000 instrument and flow cytometry. The daily intake of dairy products and related nutrients was categorized into three groups according to control distribution, and the lowest tertile was used as the reference category. An unconditional multiple logistic regression was used to estimate the odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) for asthenozoospermia risk.
Results: After adjustment for potential confounders, we found no statistically significant associations between the intake of total dairy products and asthenozoospermia risk (ORT3vs.T1 = 1.19, 95%CI = 0.85–1.67). Additionally, we generated null findings regarding the main related nutrients from dairy, including protein (ORT3vs.T1 = 1.19, 95%CI = 0.85–1.68), fat (ORT3vs.T1 = 1.28, 95%CI = 0.91–1.80), calcium (ORT3vs.T1 = 1.20, 95%CI = 0.85–1.68), saturated fatty acids (ORT3vs.T1 = 1.30, 95%CI = 0.92–1.83), and phosphorous (ORT3vs.T1 = 1.18, 95%CI = 0.84–1.67), and the asthenozoospermia risk. Of note, after stratification by body mass index (BMI), and the saturated fatty acids consumption from dairy was significantly associated with a higher asthenozoospermia risk (ORT3vs.T1 = 1.76, 95%CI = 1.01–3.09) among participants with a BMI below 25 kg/m2.
Conclusion: This study provided limited evidence of an association between the intake of total dairy products and the main related dairy nutrients including protein, fat, calcium, saturated fatty acids, and phosphorus, and the asthenozoospermia risk. Further studies are warranted to confirm our findings in the future.

背景：目前关于乳制品及主要相关乳品营养素摄入与弱精子症（asthenozoospermia）发病风险之间关联的研究证据较为有限，且存在争议。方法：本研究于2020年6月至2020年12月在中国医科大学附属盛京医院不孕不育门诊开展，为基于医院的病例对照研究，共纳入549例弱精子症患者及581例正常精子症对照人群。采用经过验证的食物频率问卷评估膳食摄入情况。参照世界卫生组织（World Health Organization）指南，通过手淫方式采集精液样本，采用WLJY9000仪器及流式细胞术检测精液参数。根据对照人群的摄入分布，将每日乳制品及相关营养素摄入量分为三组，以最低三分位组作为参照组。采用无条件多因素logistic回归模型估算弱精子症发病风险的比值比（OR）及对应95%置信区间（CI）。结果：在对潜在混杂因素进行校正后，未发现总乳制品摄入量与弱精子症发病风险存在统计学显著关联（最高三分位组vs最低三分位组的OR=1.19，95%CI=0.85~1.67）。此外，针对乳制品来源的主要相关营养素，包括蛋白质（最高三分位组vs最低三分位组的OR=1.19，95%CI=0.85~1.68）、脂肪（OR=1.28，95%CI=0.91~1.80）、钙（OR=1.20，95%CI=0.85~1.68）、饱和脂肪酸（OR=1.30，95%CI=0.92~1.83）及磷（OR=1.18，95%CI=0.84~1.67），均未观察到与弱精子症发病风险存在显著关联。值得注意的是，按体质量指数（BMI）进行分层分析后，在BMI<25 kg/m²的参与者中，乳制品来源的饱和脂肪酸摄入与弱精子症发病风险升高显著相关（OR=1.76，95%CI=1.01~3.09）。结论：本研究仅获得有限证据，表明总乳制品及蛋白质、脂肪、钙、饱和脂肪酸、磷等主要相关乳品营养素摄入与弱精子症发病风险之间不存在明确关联。未来仍需开展进一步研究以验证本研究结果。