Soy It Ain’t So!

It’s been claimed that soy foods lower LDL-cholesterol, and this claim has been allowed by the FDA. Since the analysis made to support this claim, additional studies have been done that throw it into doubt. Now an Australian study has been reported in the American Journal of Clinical Nutrition, which also brings negative results.

The participants in the study were volunteers with mildly raised total cholesterol levels (over 212 mg/dL) who normally did not eat soy products. There were 91 of them (33 men, 58 women); they consumed 3 diets for 6 weeks each in a random order. The diets contained: 1. a daily supply of 24 grams of soy protein and 70-80 grams of soy isoflavones; 2. a daily supply of 12 grams of dairy protein and 70-80 grams of soy isoflavones; and 3. a daily supply of 24 grams of dairy protein and no isoflavones.

Total cholesterol was found to be 3% lower with the soy + isoflavone diet, and the triglyceride levels were 4% lower with this diet and the dairy + isoflavone diet. Importantly, LDL-cholesterol, HDL-cholesterol, and the total cholesterol/HDL-cholesterol ratio were all unchanged by the different diets.

The bottom line: regular consumption of foods providing 24 grams of soy protein and isoflavones had no effect on blood LDL-cholesterol in subjects with mildly raised cholesterol levels. This doesn’t mean you should stop eating soy if you like it. Soy provides a healthy substitute for other foods that may do you more harm . . .