Department of Nutrition, Harvard School of Public Health, Boston, MA 02115, USA.
Hum Reprod. 2013 Aug;28(8):2265-75. doi: 10.1093/humrep/det133. Epub 2013 May 12.
Is increased consumption of dairy foods associated with lower semen quality?
We found that intake of full-fat dairy was inversely related to sperm motility and morphology. These associations were driven primarily by intake of cheese and were independent of overall dietary patterns.
It has been suggested that environmental estrogens could be responsible for the putative secular decline in sperm counts. Dairy foods contain large amounts of estrogens. While some studies have suggested dairy as a possible contributing factor for decreased semen quality, this finding has not been consistent across studies.
STUDY DESIGN, SIZE, DURATION: The Rochester Young Men's Study (n = 189) was a cross-sectional study conducted between 2009 and 2010 at the University of Rochester.
PARTICIPANTS/MATERIALS, SETTING, METHODS: Men aged 18-22 years were included in this analysis. Diet was assessed via food frequency questionnaire. Linear regression was used to analyze the relation between dairy intake and conventional semen quality parameters (total sperm count, sperm concentration, progressive motility, morphology and ejaculate volume) adjusting for age, abstinence time, race, smoking status, body mass index, recruitment period, moderate-to-intense exercise, TV watching and total calorie intake.
Total dairy food intake was inversely related to sperm morphology (P-trend = 0.004). This association was mostly driven by intake of full-fat dairy foods. The adjusted difference (95% confidence interval) in normal sperm morphology percent was -3.2% (-4.5 to -1.8) between men in the upper half and those in the lower half of full-fat dairy intake (P < 0.0001), while the equivalent contrast for low-fat dairy intake was less pronounced [-1.3% (-2.7 to -0.07; P= 0.06)]. Full-fat dairy intake was also associated with significantly lower percent progressively motile sperm (P= 0.05).
LIMITATIONS, REASONS FOR CAUTION: As it was a cross-sectional study, causal inference is limited.
Further research is needed to prove a causal link between a high consumption of full-fat dairy foods and detrimental effects on semen quality. If verified our findings would mean that intake of full-fat dairy foods should be considered in attempts to explain secular trends in semen quality and that men trying to have children should restrict their intake.
STUDY FUNDING/COMPETING INTEREST(S): European Union Seventh Framework Program (Environment), 'Developmental Effects of Environment on Reproductive Health' (DEER) grant 212844. Grant P30 DK046200 and Ruth L. Kirschstein National Research Service Award T32 DK007703-16 from the National Institutes of Health. None of the authors has any conflicts of interest to declare.
食用更多乳制品是否与精液质量下降有关？
我们发现，全脂乳制品的摄入量与精子活力和形态呈负相关。这些关联主要是由奶酪的摄入量驱动的，且与整体饮食模式无关。
有人认为环境雌激素可能是精子数量推测性的长期下降的原因。乳制品中含有大量的雌激素。虽然一些研究表明乳制品可能是精液质量下降的一个潜在因素，但这一发现并非在所有研究中都一致。
研究设计、规模、持续时间：罗切斯特年轻男性研究（n = 189）是 2009 年至 2010 年在罗切斯特大学进行的一项横断面研究。
参与者/材料、设置、方法：本分析纳入了 18-22 岁的男性。通过食物频率问卷评估饮食。线性回归用于分析乳制品摄入量与常规精液质量参数（总精子数、精子浓度、前向运动精子百分率、形态和精液量）之间的关系，调整因素包括年龄、禁欲时间、种族、吸烟状况、体重指数、招募期、中等强度至剧烈运动、看电视时间和总热量摄入。
总乳制品摄入量与精子形态呈负相关（P 趋势=0.004）。这种关联主要是由全脂乳制品的摄入量驱动的。在全脂乳制品摄入量最高和最低的两组男性中，正常精子形态百分比的调整差异（95%置信区间）为-3.2%（-4.5 至-1.8）（P<0.0001），而低脂乳制品摄入量的相应差异则不那么明显[-1.3%（-2.7 至-0.07；P=0.06）]。全脂乳制品摄入量也与显著较低的前向运动精子百分率相关（P=0.05）。
局限性、谨慎的原因：由于这是一项横断面研究，因此因果推断受到限制。
需要进一步的研究来证明大量食用全脂乳制品与精液质量下降之间存在因果关系。如果这一发现得到证实，那么我们的研究结果将意味着应该考虑摄入全脂乳制品，以解释精液质量的长期趋势，并且试图生育的男性应该限制他们的摄入量。
研究资金/利益冲突：欧盟第七框架计划（环境），“环境对生殖健康的发育影响”（DEER）赠款 212844。来自美国国立卫生研究院的 P30 DK046200 赠款和 Ruth L. Kirschstein 国家研究服务奖 T32 DK007703-16。作者均无利益冲突。
