如果你的“牛奶”来自大豆而不是奶牛，你可能要考虑可能的激素影响。大豆中含有一种叫做异黄酮的物质，它具有荷尔蒙活性——尤其是雌激素——但是关于大豆对睾酮的影响，目前还没有定论。
研究结果不同
2010年8月发表在《生育与不育》(Fertility and Sterility)上的一篇文章称，在食用大豆食品或大豆制品的成年男性中，大豆蛋白和大豆异黄酮都对睾丸激素水平没有任何影响。This article was a meta-analysis, which is a review of many studies on one subject. Since that time, however, two research studies have produced different findings. Men who performed heavy resistance exercises after supplementation with soy protein for 14 days developed decreased serum testosterone, according to a 2013 article published in the "Journal of the American College of Nutrition." Another article reported that when male rats were exposed to soy isoflavones in the first three weeks of life, testosterone production increased, according to findings in the February 2014 article in "Biology of Reproduction."