Soy perfectly safe, insist experts
Scientists have issued a robust defence of soy in the wake of a series of media attacks on the ingredient on both sides of the Atlantic, linking it to health problems ranging from cancer to infertility.
Speaking at the Soy and Health conference in Düsseldorf last week, which brought together scientists and physicians conducting clinical trials into the health benefits of soy, Mark Messina, associate professor at Loma Linda University in the US, said: “Almost without exception, those questioning the safety of soy are drawing upon a handful of in vitro studies or trials on animals that use extremely high does of soy isolates, not soy foods. But rodents metabolise soy isoflavones very differently to humans.”
He added: “When you look at the clinical trials conducted on humans, the evidence that soy foods are not only safe, but positively beneficial for health, is overwhelming.”
While soy isoflavones have oestrogen-like qualities under certain conditions, which critics claim could lead to premature development of oestrogen sensitive organs in young children, “it should be noted that more than 22M infants are estimated to have been fed soy formula in the US since 1965 and the incidence of adverse health effects in this group is no greater than in counterparts fed on breast milk,” said Messina.
“Unfortunately, scare stories in the press have had an impact on how the public perceives the value of soy and as result, health professionals and the industry need to do a much better job at communicating its merits to diet and health.”
Although soy’s ability to reduce cholesterol was now established beyond any doubt, more research was needed before food manufacturers were likely to secure regulatory approval to make claims about its ability to reduce the risk of certain cancers, ease menopausal symptoms, promote immune function, and boost bone, eye, and cognitive health, said Messina.
While the new European Nutrition and Health Claims Regulation would enable companies to apply to make claims about disease risk reduction, with so many variables at play it was hard to see how anyone could make a truly compelling case about the efficacy of bioactive ingredients in tackling chronic disease, he added.
“That it is not possible to definitely conclude that soy foods reduce the risk of chronic disease is hardly surprising because the etiology of most chronic diseases is highly multifactorial and they have such long latency periods,” he said.
Furthermore, most nutrition-related clinical trials involved small subject numbers and were generally of short duration, which made inconsistent results more likely, added Messina.
