London Guardian 
Thursday, July 24, 2008
Men who eat soya-based foods may be harming their fertility, doctors said yesterday, after a study found a link between soya-rich diets and lower sperm counts.
The study showed men who consumed more than two portions of soya-based foods a week had, on average, 41m fewer sperm per millilitre of semen than men who had never eaten soya products.
The apparent fall in sperm count is unlikely to make healthy men infertile, but some experts said it could have a significant impact on those already with lower than average sperm counts. A sperm count of between 80m and 120m per ml is regarded as normal, while men who produce fewer than 20m sperm per ml are regarded as clinically subfertile.
(Article continues below)
The study, by Jorge Chavarro at Harvard school of public health in Boston, builds on previous research in animals and on human tissues that has suggested certain ingredients in soya could harm sperm production.
Male fertility has been in decline in the west for several decades, with about 20% of young Europeans having a low sperm count, while levels of soya have risen steadily in the western diet since the 1940s because it is a cheap source of protein. Soya-based products are now found in two-thirds of manufactured food including biscuits, sweets, pasta and bread, according to the Institute of Food Research in Norwich.