Somewhere along the way, people realized that the soybean—besides its protein content—had other nutritional benefits as well: it contains few saturated fats; has no cholesterol; and provides isoflavones, minerals, and fiber. Some believe that all these characteristics make soy an effective disease fighter, working hard to combat certain cancers, strokes, and heart disease.

Some point out that, as a rule, Asians suffer from fewer of these diseases than Westerners, with their rich meaty diets, and they believe that soy consumption is one reason for that. Other studies suggest that soy’s properties may also combat osteoporosis, type 2 diabetes, and even obesity.

But, as it turns out, while some people describe soy as a “miracle” food, some skeptics challenge the prevalent notion that soy should be a staple in everyone’s diet, replacing meat partially or totally. If you scroll through the web, you’ll find plenty of conflicting arguments about the pros and cons of soy that will leave you completely mystified.

Soy Is Good for You

In a 1999 ruling, the FDA allowed food manufacturers to label their soy-based food—foods made with the whole soybean without any added fats and that contain at least 6.25 grams of soy protein per serving—as beneficial for keeping hearts healthy. That approval apparently opened the floodgates of soy’s popularity, and production of soyfoods soared.

In a 2000 FDA Consumer magazine article entitled “Soy: Health Claims for Soy Protein, Questions about Other Components,” author John Henkel pinpoints the various health benefits of soy in the diet, stating that soy is a good substitute for animal protein because it is a complete protein, containing all the amino acids humans require without high levels of saturated fats. Referring to earlier studies, the author also notes that research suggests that soy proteins may lower the bad cholesterol levels in blood without affecting good cholesterol levels. In addition, eating soy may reduce the incidence of osteoporosis and certain cancers—studies were underway to determine soy’s efficacy in these conditions.

Following the FDA’s endorsement of soy and its possible benefits, the American Heart Association issued an advisory recommending soy products, with their polyunsaturated fats and fiber and low saturated fat, as possibly beneficial as a source of protein.

Soy Is Not Good for You

On the other side of the soy debate, soy detractors point out that eating soy not only has drawbacks, but also could have serious health effects. Some consumers have claimed that soy in infant formulas lowers IQ; others say soy causes thyroid problems.

The FDA itself in its 2000 article on soy confirmed that the jury may still be out for much of soy’s touted health claims, particularly relating to soy isoflavones, which are a weak form of estrogen and in high levels could increase the risk of breast cancer; however, a study published by the Cancer Project News in 2006 and conducted by the Johns Hopkins School of Medicine found that high soy intake actually reduced breast cancer risk, particularly for premenopausal women.

An additional soy detractor is the D.C.-based Weston A. Price Foundation, which has filed a petition with the FDA asking the government agency to amend its earlier pro-soy statements. The petition suggests that soy may play a role in promoting certain cancers, in initiating thyroid diseases, and causing reproductive problems. It cites that the to-date scientific findings about soy’s health benefits are inconclusive.

Additionally, the American Heart Association’s Nutrition Committee, after reviewing twenty-two studies, is slightly revising its earlier statement about soy intake and its relationship to heart disease. Its conclusion: soy protein reduced harmful cholesterol by only 3 percent and had virtually no effect on lowering blood pressure. The committee’s report added that the findings on soy protein’s worth in preventing or treating breast or prostate cancers is not established. But researchers did note that using various soy products with their polyunsaturated fats to replace high-fat proteins had dietary benefit.

Many people report allergic reactions to soy proteins, a fact substantiated by the Asthma and Allergy Foundation of America, which reports that soy is one of the most common allergens in the market. It also notes that not all soyfoods cause a reaction, but since soy is now prevalent in many food products, even if the label does not state that soy is present, avoiding soy for the allergy sufferer becomes a challenge.

Draw Your Own Conclusions

As in all cases, the informed consumer is the best consumer. It’s reasonable to assume that many of the modern soy products are not produced, formulated, or processed in the way the ancient Chinese and Japanese soy masters made their tofu. Therefore, you should select soyfoods that are basically whole soy or based on soy proteins, without overprocessing or many added ingredients: as a consumer, figure out the many ways to bring soy to your table. And as with all foods—and with anything in life—moderation is the key.