The Crucial Soy Link

In view of the recent news on the health benefits of soy protein, what do we find in our China Project? Since China is one of the leading producers and consumers of soy products in the world, their use of this food may be of special interest. First, recall that our survey included a total of 65 mostly rural counties across the far reaches of the country, with two villages of 50 families each being surveyed in each county. Also recall that disease rates and diets varied enormously from area to area, thereby creating very distinct geographical patterns for heart disease, various cancers and so on. Because most rural Chinese rarely move to other areas and they eat mostly the same kinds of food throughout their lives, we find an almost perfect experimental setting to compare diet, lifestyle, and disease characteristics. Although consumption of soy products was not measured independently of other legume intakes, this does not compromise our question very much because soybeans comprised, on average, about 80% of the total legumes actually consumed. In fact, the Chinese word for soybean is “tatou,” meaning “the greater bean.” Total legume intake in China ranged from virtually nothing in a few counties to average daily intakes of 55-58 g/day for three counties (about two ounces, fresh weight). Surprisingly, average intakes across the whole of China were not as high as we had expected. We should recognize, however, that the survey included mostly rural counties where legumes have often been considered more of a luxury food than a regular staple. Thus, any cholesterol-lowering effects of soy protein itself are largely buried within the total diet effects and would be difficult to dig up.

Soy…The Rest of the Story

How interesting it is to see the recent flurry of soy stories hit the press.

Products such as tempeh, tofu, and soy burgers vie daily for headlines with reports of seemingly miraculous benefits all credited to the simple and versatile soybean. This latest wave of interest reached an unprecedented fervor after Dr. James Anderson and his group at the University of Kentucky published in August of 2005 a comprehensive summary of 37 individual human studies. Their conclusion: soy protein can, indeed, reduce blood cholesterol, especially the so-called “bad” kind (LDL).

As some of you who have been following my work over the years may know, I’ve been a long-time proponent of this soy-protein effect, so I was heartened to see these results finally brought into the public spotlight. Nevertheless, I would like to ask three pertinent questions. First, why is this finding just now being reported? It really is a very old story. Second, why are the news accounts focused exclusively on soy protein when there is good evidence that many other plant proteins, if not virtually all, have much the same cholesterol effect? And third, why is the emphasis being placed on the “cholesterol-lowering” effects of soy protein rather than the more devastating “cholesterol-raising” effects of animal protein?

Why Has it Taken so Long to Tell the Soy Story?

Since the beginning of this century, numerous studies with experimental animals have shown conclusively that soy protein, when compared with the milk proteins casein and lactalbumin, can dramatically reduce blood lipids such as total cholesterol, LDL (“bad”) cholesterol, and triglycerides. Particularly impressive findings were published between the years 1941 and 1965, with many more studies (especially among humans) following thereafter. It’s my opinion that the scientists who [...]