14 DAY TRIAL // Multiple studies have shown that animals that consume large amounts of soy beans are likely to have a lower fertility rate. On the other hand, research regarding the impact of soy on humans revealed that the chemicals found in this plant have absolutely no effect on fertility. Now, a new study carried out at the Harvard School of Public Health suggests that even small amounts of food containing soy could reduce the sperm concentration by as much as half.
By studying the diet of 99 men with fertility problems, researchers found that the amount of soy based foods they ate on a daily basis had a significant impact on their reproductive cell count. Usually, the cell concentration is somewhere between 80 and 120 million per milliliter, as compared to 41 million less in the case of men eating on average a serving of soy-based food every day.
Leader of the study, Dr Jorge Chavarro, believes that the chemicals responsible for this effect, known as isoflavones, could be able to mimic a human hormone called oestrogen. High levels of oestrogen can also be caused by the increase of body fat levels, which could explain why overweight and obese men are prone to fertility problems.
The same cannot be said about men living in many parts of the Asian continent, where the soy bean plant comes from, who, although they consume significantly higher amounts of soy than the participants in the study, do not appear to have their fertility impaired.
"Many men are obviously worried about whether their lifestyle or diet could affect their fertility by lowering their sperm count. Oestrogenic compounds in food or the environment have been of concern for a number of years, but we have mostly thought that it was boys exposed in the uterus before birth who were most at risk," said senior lecturer in andrology Dr. Allan Pacey of the University of Sheffield.
"We will have to look at adult diet more closely, although the fact that such large parts of the world have soy food as a major part of their diet and don't appear to suffer any greater infertility rates than those on western diets suggests that any effect is quite small," he added.