Sydney School of Veterinary Science, The University of Sydney, Sydney, Australia.
Charles Perkins Centre, The University of Sydney, Sydney, Australia.
Obes Rev. 2019 Jun;20(6):921-933. doi: 10.1111/obr.12827. Epub 2019 Feb 12.
Sperm counts have shown a progressive decline across the world since the mid-1900s. Global rates of obesity have been climbing at a similarly alarming rate, suggesting that these two factors may be linked. However, studies examining the relationship between body mass index (BMI) and male fertility have produced conflicting results. These discrepancies among studies are commonly attributed to limitations that are inherent in human studies such as correlational data and confounding factors-limitations that are absent from animal studies. Hence, we conducted a systematic review and meta-analysis of animal studies that experimentally induced obesity with a high-fat diet and measured impacts on sperm traits and/or male fertility. Overall, we found strong, consistent evidence in animal studies that high-fat diets are detrimental for male fertility. Compared with controls, males fed a high-fat diet had smaller testes and sex accessory glands relative to body size, reduced semen quality, reduced mating success, and reduced fertilization success. This is the first time that experimental data of high-fat diet effects on male reproduction have been synthesized in a meta-analysis, and thus, our results provide novel insight to the complex question of how dietary-induced obesity affects male fertility. The strong negative effects detected in animal models suggest that the inconsistent results plaguing human studies are an artefact of limitations inherent in correlational studies rather than a true effect.
自 20 世纪中叶以来，全球精子数量呈持续下降趋势。全球肥胖率也呈同样惊人的速度攀升，这表明这两个因素可能存在关联。然而，研究肥胖症与男性生育力之间关系的研究得出了相互矛盾的结果。这些研究之间的差异通常归因于人类研究固有的局限性，如相关数据和混杂因素，而这些局限性在动物研究中并不存在。因此，我们对用高脂肪饮食诱导肥胖的动物研究进行了系统回顾和荟萃分析，并评估了这些研究对精子特征和/或男性生育力的影响。总的来说，我们在动物研究中发现了强有力的一致证据，证明高脂肪饮食对男性生育力有害。与对照组相比，喂食高脂肪饮食的雄性动物相对于体重而言睾丸和附属生殖腺较小，精液质量下降，交配成功率降低，受精成功率降低。这是首次对高脂肪饮食对男性生殖的影响进行荟萃分析，因此，我们的结果为饮食引起的肥胖如何影响男性生育力这一复杂问题提供了新的见解。在动物模型中检测到的强烈负面影响表明，困扰人类研究的不一致结果是相关研究固有局限性的人为产物，而不是真实的影响。
