Soy Milk Complications

No longer just the drink of choice for vegetarians and those allergic to milk, in the last few years soy milk sales have rocketed by 20 percent annually and is so popular that some supermarket chains even produce their own in-house brands. While soymilk does have it benefits, research has shown that there is a darker side as well.

Impaired Fertility

• Soymilk can increase the risk of infertility. According to Dr. Lorraine Anderson, a specialist in reproductive medicine at Belfast's Royal Maternity Hospital, phytoestrogen, which is found in soybeans, causes sperm motility, which means sperm has a harder time moving toward and fertilizing an egg. Her study showed that infants who were fed only soymilk formula received an oestrogen doze that was equal to five birth control pills daily. Leading British fertility expert, Professor Neil McClure said, "If a couple were having trouble conceiving and the man's sperm was a borderline case, then I have seen enough evidence from these studies to advise a change in his diet to minimize soy."

Thyroid Problems

• Soymilk can cause thyroid problems. Environmental scientist and phytoestrogen researcher Dr. Mike Fitzpatrick conducted studies, which revealed that soymilk has isoflavones, which act as potent anti-thyroid agents. Isoflavones in soymilk can suppress thyroid function and aggravate hypothyroidism. Because soy is a phytoestrogen, it reacts like an oestrogen within the body, upsetting the thyroid's hormonal system. People who consume high quantities of soymilk are also at a greater risk of developing goiters.

Kidney Stones

• A study in the published in the Journal of Agricultural and Food Chemistry reports that excessive consumption of soymilk can lead to kidney stones. In this study, almost a dozen varieties of soybeans were measures for oxalate, a compound that binds with calcium to form kidney stones. The amount of oxalate found in most commercial soy products was much greater than the 10 milligram-per-serving recommended for people suffering from kidney stones. Some soy milk products have oxalate levels that at 50 times higher than recommended. According to Professor Linda Massey at Washington State University in Spokane, "Under these guidelines, no soybean or soy-based food tested could be recommended for consumption by patients with a personal history of kidney stones."