Another Look at Soy

The latest issue of the journal Nutrition and Cancer reports on a study by Korean researchers showing a protective effect of soy on the risk of developing breast cancer.

If you've read my book, "The 150 Healthiest Foods on Earth" you know that I've not been a huge fan of soy. And if you've read any of the writings of Sally Fallon and Mary Enig ("The Ploy of Soy") or the book, "The Whole Soy Story: The dark side of America's favorite health food" by Kalia Daniels, PhD, CCN, you probably know why.

Yet studies like this new one continue to pop up and can't be responsibly ignored. So I took some time to "re-evaluate" the whole soy controversy and would like to share some of my thoughts about it.

First, the new study. Researchers at Hanyang University in Seoul, Korea compared 362 women diagnosed with breast cancer with an equal number of healthy women matched for age and menopausal status. Participants were interviewed concerning their diets, and total soy protein intake was used as a measure of total soy food consumption.

High soy protein intake was associated with a reduced risk of breast cancer. The researchers divided the women into five tiers depending on their soy consumption. Premenopausal women who were in the highest 20% for consumption of soy protein had a 61 percent lower adjusted risk of breast cancer compared with those in the lowest 20% of consumption. For postmenopausal women, those consuming the highest soy protein intake had a 78% lower risk.

But here's the thing- look at the kind of soy they were consuming. "Tofu, soybean paste, boiled soybeans and soy milk". This study was done in Korea. I've often said that the type of soy they consume in Asian countries is considerably different than the soy junk food we consume over here, a point that has been made by Fallon, Enig and Daniel many times.

Fact is, fermented soy is a whole different story, and even those who are "anti-soy" agree that this can be good stuff.

But that's a far cry from the stuff that lines the "health food" section of your local supermarket- soy products, soy chips, soy derivatives, soy concentrates, soybean oil and soy ice cream. These food products have little in common with traditionally fermented soy foods from the whole bean like tempeh, miso and the like.

Coincidentally, an excellent and well-researched article in this month's Townsend Newsletter for Doctors and Patients asks- and attempts to answer- the question "why the conflicting research on soy?" The article is detailed and well-researched and summing it up in a couple of sentences doesn't do it justice.

But here's the bottom line: All soy products are very far from equal.

As the Townsend Newsletter article points out, epidemiological studies examining the relationship between soy intake and health outcomes "have involved Asian populations and therefore evaluated the intake of traditional fermented foods such as tofu and other soy products that are derived from whole or dehulled soybeans". This is a far cry from many of the studies that use soy concentrates, soy isolates, isolated isoflavone mixtures or pure genisten.

"There are dozens of soy products used for research, and they differ markedly in micro (isoflavone, saponin, phytic acid, phytosterol, vitamin and mineral content) and macro (protein, fat and carbohydrate) content" says the author, Walter Wainright.

He's absolutely right.

This newsletter item isn't an attempt to resolve the soy controversy, which is complicated and fueled by partisanship and passion on both sides. I think the point here is that soy isn't always "bad" and it certainly isn't always "good". Like everything else in food and supplements, the source and quality and nature of the product is a huge determinant when it comes to sorting out its effects.

Grass-fed meat isn't the same as ballpark hot dogs- and "soy isolate" isn't the same thing as fermented miso. In an era when we tend to reduce complex issues to manageable sound bites ("soy is good" "soy is bad") it's good to remember that all soy products are not created equal.