The Great Soy Formula Experiment

From Undark Truth, Beauty, Science, August 2, 2017.

Soy milk and soy formula contain potent human hormone disruptors. We don’t know what this means for child development.

I’m hesitating over this one question I want to ask the scientist on the phone, a federal researcher studying the health effects of soy formula on infants. I worry that it’s going to sound slightly Dr. Frankenstein-esque. Finally, I spill it out anyway: “Are we talking about a kind of accidental experiment in altering child development?”

With our fondness for all things soy, have we created a kind of inadvertent national study?

The line goes briefly silent. “I’m a little worried about the word ‘experiment,’” replies Jack Taylor, a senior investigator at the National Institute of Environmental Health Sciences, a division of the National Institutes of Health. Taylor and his colleagues in North Carolina have been comparing developmental changes in babies fed soy formula, cow-milk formula, and breastmilk. His group’s most recent paper, “Soy Formula and Epigenetic Modifications,” reported that soy-fed infant girls show some distinct genetic changes in vaginal cells, possibly “associated with decreased expression of an estrogen-responsive gene.”

But his first reaction is that my phrasing would, incorrectly, “make it sound like we were giving children a bad drug on purpose.” The research group, he emphasizes, is merely comparing the health of infants after their parents independently choose a preferred feeding method. No one is forcing soy formula on innocent infants.

“No, no, that’s not what I meant,” I explain with some hurry. “I wasn’t suggesting that you were experimenting on children.”

Rather, I was wondering whether we as a culture, with our fondness for all things soy, have created a kind of inadvertent national study. Soy accounts for about 12 percent of the U.S. formula market and I’ve become increasingly curious about what this means. Because the science does seem to suggest that we are rather casually testing the effect of plant hormones on human development, most effectively by feeding infants a constant diet of a food rich in such compounds.

Research shows that soy milk and soy formula contain up to 4,500 times the level of phytoestrogens found in cow’s milk or breastmilk. That’s a notable number. And it’s been associated with remarkably high levels of these compounds circulating in the bloodstreams of soy-fed infants. All of this matters when you consider that phytoestrogens are potent human endocrine disruptors, binding efficiently to the estrogen receptors found in both females and males. And consider further, that a baby on a soy formula diet is being repeatedly dosed every day.

Read the full article.