British researcher has discovered a plant chemical found in soy, tofu and legumes that potentially could damage sperm and affect male fertility.

Professor Lynn Fraser, of King's College London has shown that soy isoflavones, can mimic the effect of the female hormone estrogen and affect sperm in mice.

What are Isoflavones

Isoflavones is type of phytoestrogen, or plant hormone, that resembles human estrogen. Isoflavones are found in soybeans, chick peas and other legumes.

Dr. Fraser commented that her researched showed that soy was not only a problem for mice sperm but she was afraid it could even have a stronger impact on human sperm.

In laboratory tests, Fraser found that small amounts of the chemical can cause sperm to "burn out" and lose fertility.

Another Problem

Dr. Fraser stated that women who eat soy and other foods high in soy might have a bigger impact on male fertility because the chemical is likely to affect sperm when it is in the female preparing to fertilize an egg.

Although it is very preliminary research, Fraser speculated that the findings could have an impact on women trying to conceive.

Warning for Men and Women

Based on her research, Dr. Frazer informed the European Society of Human Reproduction and Embryology that it might be wise to restrict eating lots of soy-based products during ovulation.

Dr Allan Pacey, of the University of Sheffield in England, said it is worrying if these compounds affect mature sperm.