Eating foods with high levels of phytoestrogens can help women with low estrogen levels improve bone density and can relieve skin dryness and hot flashes. Men on similar diets can suffer effects such as swollen breasts, reduced sperm count, increased emotional volatility and loss of libido, according to Men's Health.
Phytoestrogens are naturally occurring plant chemicals that are converted to estrogen in the human body. Common sources include soybeans and other legumes, baker's yeast, olives and olive oil. Apples, potatoes, wheat, barley and oats also contain phytoestrogens. Some natural health providers and nutritionists support a diet rich in phytoestrogens to manage menopausal symptoms, and in moderation, these foods are good for most people.
High levels of phytoestrogens are another story, particularly when exposure occurs before birth and during the period prior to puberty. There is some evidence that consuming these chemicals can change the timing and development of the breasts in girls and may also affect the prenatal development of the brain and reproductive system. Other concerns are possible negative effects on immune system function and development in infants and on dementia in adults older than 65. In a 2010 paper, the National Center for Biotechnology Information summarized the available data by acknowledging the contradictory or preliminary nature of many studies and cautioned that the benefits or harms caused by phytoestrogens may depend on a complex interaction between age, health status and the presence or absence of specific gut microflora.