Does the type of soy food matter?

To date, there have only been a few studies in humans directly comparing the health effects of different soy foods.

Researchers from Harvard School of Public Health examined the effects of a soy protein containing diet and a soy nut (whole roasted soybeans) containing diet, compared to a control diet on features of the 'metabolic syndrome'. The results from this study showed that soy nuts had a more significant effect than soy protein on reducing blood fat levels as well as markers of the metabolic syndrome including an improvement in insulin sensitivity, a reduction in fasting plasma glucose and serum C-peptide levels (a marker of insulin resistance) ¹⁶ .

In contrast, a study from Stanford University found that soymilk made from soy protein and soymilk made from whole soy beans both equally lowered LDL cholesterol levels by approximately 5%, relative to dairy milk ¹⁷ .

Another study by Matthan and Jalbert et al (2007) compared the effect of three different types of soy foods to animal protein for cardiovascular disease risk factors: 1) Whole soybeans/soy nuts and foods made from whole soybeans (defatted soy flakes, soya granules and soy-nut butter); 2) Soy flour and 3) Soymilk. In this study, LDL cholesterol was significantly lower after the soymilk containing diet compared to the diet with animal protein or soy flour. HDL cholesterol and apolipoprotein A-I concentrations were higher on the soymilk diet when compared to the whole soybean and soy flour diets ¹⁸ . HDL cholesterol is the "good cholesterol", therefore, high concentrations are beneficial for heart health.

At present, there is insufficient evidence to determine which soy foods may provide greater heart health benefits. Based on population studies in Asia and numerous clinical trials, it seems that a range of soy foods can boost health and lower cholesterol levels.