US soy producers on Wednesday disputed a Harvard School of Public Health study that shows products containing soy and isoflavones can result in reduced sperm count among men.
"Headlines claiming 'soy products lower sperm count' do not tell the whole story," the Soyfoods Association of North America said in a statement challenging the methods used in the medical study, the first to relate soy to fertility problems in humans.
The Harvard study examined the soy intake of 99 men experiencing fertility problems for three months and found that isoflavones in soy act like female hormones, giving "an inverse association between soy food intake and sperm concentration."
The Soyfoods Association said the study "conflicts with the large body of US government and National Institutes of Health-sponsored human and primate research, in which controlled amounts of isoflavones were fed and no effect on quantity, quality or motility of sperm were observed."
The Harvard study led by Jorge Chavarro and published in Human Reproduction journal "is the first to find this correlation" between soy ingestion and low sperm count, said University of Alabama at Birmingham pharmacologist Stephen Barnes in the statement.
The European Natural Soyfoods Manufacturers Association also disputed Chavarro's study from a different approach.
"Generations of Asians have regularly consumed soya without fertility disorders, and Asian countries have prodigiously produced very healthy, highly-functioning children for centuries," the European group said.