Soy Protein & Isoflavones

Article by Don Goldberg

 

Soy Protein & Isoflavones

In the introduction to his book, The Soy Revolution, Stephen Holt, M.D., founder of Biotherapies Inc, says the following:

"Soy and soy products have long been known as halthful and useful additions to our diet, But it is only recently that medical studies have begun to prove what Asians have believed for centuries: that soybeans and soy products are amazingly effective in the prevention and treatment of many widespread diseases and conditions.

Dr. Holt points out that soy:

•protects agains possible unwanted effects of estrogens,

•has potent anti-cancer effects,

•has been credited with the reduced incidence of prostate cancer among asian men

•helps in the fight agains diabetes mellitus

•may have an anti-agniogenice effect (diabetic retinopathy, which causes blindness)

•prevents and treats osteoporosis

Dr. Holt is not alone in his enthusiasm for soy and soy supplements.

Dr. Suzanne Paxton, a world-renowned phytopharmacologist, involved in the soy food industry, and author of a book on soy sponsored by Lumen Foods, reports on the following recent developments:

Preventing the Causes of Heart Disease

Heart Disease & Diet: The University of Toronto Study

The current barrage of studies coming out points specifically to correlations between soy protein consumption and these same lower rates. In 1990 Lumen Foods proudly participated in a study at the University of Toronto, funded by Canada's National Institute of Health. The study, headed by David J.A. Jenkins, M.D. at the Department of Nutritional Sciences (Faculty of Medicine, University of Toronto), was published in the July, 1993 issue of The New England Journal of Medicine. It concluded that: "... very high intakes of foods rich in soluble fiber lower blood cholesterol levels even when the main dietary modifiers of blood lipids -- namely, saturated fat and cholesterol -- are greatly reduced." In a private letter to this author Dr. Jenkins, the study's principal researcher, wrote that subjects who were served our Heartline products saw... "very significant fall(s) in total serum cholesterol... irrespective of whether they were taking soluble or insoluble fiber supplements." Nonetheless, the final paper (N Engl J Med 1993; 329:21-26(7/1/93) did not distinguish between vegetable protein and soy protein as such.

 

The "University of Kentucky" Meta-Analysis

This "meta-analysis" of 38 controlled clinical studies was far more specific in addressing soy protein's affect on serum lipid concentrations. The study itself (N Engl J Med 1995; 333:276-82(8/3/95) was far reaching in methodology and coverage. Among its statements and conclusions:

Background: It has been known for over 80 years that soy protein has cholesterol-lowering effects far exceeding those of animal protein when studied in animals. Recent studies have merely attempted to confirm that humans respond similarly to other mammals. Soy protein is well-known to produce less hypercholesterolemia and less atherosclerosis in animals than animal protein.

The analysis took in account a wide variety of soy protein sources among the 38 clinical studies: textured soy protein (such as Heartline), soy protein concentrate, and soy isolates. Nonetheless, of 38 studies 89% (34) reported a net decrease and 11% (4) reported a net increase in serum cholesterol concentrations. However, in these 11% of the studies the initial serum cholesterol values among subjects was already fairly low (average, 185 mg/deciliter). Changes i