New research has shown that women who ate a lot of beef while pregnant had sons who were more likely to suffer from poor sperm quality as adults, and it suggests that the growth promoters used in cattle may play a role in these men?s reduced fertility.
The study of men living in the USA and born between 1949 and 1983 revealed that those whose mothers ate more than seven beef meals a week had a sperm concentration that was over 24% lower than in men whose mothers ate less beef.
In addition, three times more sons of high beef consumers had a sperm concentration that would be classified as sub-fertile according to World Health Organization standards, in comparison to men whose mothers ate less beef.
Professor Shanna Swan, the lead author of the study that is published online in Human Reproduction journal today (Wednesday 28 March), said: “These findings suggest that maternal beef consumption is associated with lower sperm concentration and possible sub-fertility, associations that may be related to the presence of anabolic steroids and other xenobiotics in beef.”
In the Associate Editor?s Commentary to the study, Frederick vom Saal, professor of biology at the University of Missouri, Columbia, USA, warned that if foreign chemicals (xenobiotics) such as anabolic steroids were involved in reducing sperm quality, it could be just “the tip of the iceberg” and that the xenobiotics might be involved in other reproductive problems as well.
“Furthermore, women would also be expected to be affected by developmental exposure to xenobiotic hormones; studies relating maternal beef consumption to daughters? incidence of polycystic ovarian syndrome, age at puberty and postnatal growth rate would be predicted to show a significant relationship,” he said.
Growth promoters for cattle, such as the synthetic hormone diethylstilbestrol (DES), have been used in the USA since 1954. Although DES was banned for use in cattle in 1979, other hormones such as oestradiol, testosterone, progesterone, zeranol, trenbolone acetate and melengestrol continue to be used. Residues of these chemicals remain in the meat after slaughter and so, in the USA, the FDA has regulated their use to avoid unintended adverse effects in humans eating the meat and defined an “acceptable daily intake”. The International Joint Food and Agricultural Organization?s World Health Organization Expert Committee on Food Additives (JECFA) has also published ADIs. In Europe, the use of these hormones has been banned since 1988.