Soy foods likely play a key role in preventing heart disease, according to a University of Toronto study in the June issue of the journal Metabolism.
Researchers were able to reduce the levels of "bad" cholesterol -- while still preserving "good" cholesterol levels -- in healthy middle-aged men and women by feeding them modest amounts of soy foods over two one-month periods.
"We're only beginning to understand the potentially powerful health benefits of soy," says lead author David Jenkins, a professor of nutritional sciences at U of T and director of the Risk Factor Modification Centre, St. Michael's Hospital. "These findings demonstrate the power of certain foods in the fight against cholesterol and may explain why heart disease is so rare in East Asian countries where soy consumption is much higher."
Jenkins' team of researchers studied 19 men and 12 women with elevated concentrations of harmful LDL (low density lipoprotein) cholesterol. Subjects were fed a low-fat, low-cholesterol diet that doubled intake of soluble fibre and replaced most animal protein with vegetable protein from soy, other legumes and cereals, meat substitutes and vegetarian cold cuts.
Compared to the low-fat control diet, the test diet significantly lowered total cholesterol levels, LDL cholesterol and the ratios of good to bad cholesterol levels. "Dietary strategy needs to be broadened to include high soluble fibre and soy protein foods which are also low in saturated fat."
These cardiovascular benefits are supported by a second study presented by Jenkins demonstrating that in the same subjects, smaller amounts of the same soy foods prevented oxidation of LDL cholesterol -- a process which damages the coronary artery lining, creating an even greater risk of heart disease.
Results of both studies will be presented at the annual meeting of the Canadian Federation of Biological Societies in Winnipeg on Saturday, June 5. Funding was provided by the University-Industry Research Partnership Program of the Natural Sciences and Engineering Research Council of Canada and Loblaw Brands Ltd.
Journal
Metabolism