Research published in the Proceedings of the National Academy of Sciences threw more flame on the fire over the safety of soy-based products.
Researchers reported that infants who drink soy-based formula are exposed to 200 times as much genistein — a hormone-like compound — than are children who consume either breast milk or cow’s milk. The total amount of genistein from soy-based infant formula was 10 times that amount that an adult on a diet high in soy products would be exposed to.
Why should anyone care? Because genistein has been linked to suppression of the immune system in animals. Mice who were injected genistein saw an 80 percent decrease in the size of their thymus and an 86 percent reduction in the production of immune cells. Results were not quite so dramatic when mice were given genistein in their diet, but even in those mice the thymus size declined by 10 to 25 percent.
The researchers recommended that,
In light of our present results and other work suggesting potential immune, reproductive, and endocrine effects, the use of soy formula for infant nutrition and high soy/isoflavone intake by adults through the use of supplements needs to be approached with caution.
As I’ve said before, research in this area is intriguing but far from convincing. Much more research on soy in both animals and human beings will eventually clear up the situation, but in the meantime the evidence that soy-heavy diets are potentially harmful is sparse at best.
Source:
Soy-based infant formulas may hinder immune system. Rachael Moeller, Scientific American, May 21, 2002.