Consumption Of Soy Protein May Reduce Risk Of Heart Disease

Soy beansDiets high in soy may reduce the incidence of heart disease according to recent studies. One such study, published in The Journal of Clinical Nutrition in 2002, looked at 64,915 women from Shanghai, China, in order to determine the effects of soy food consumption on the risk of coronary heart disease.

Over an average follow up period of 2.5 years, 62 new cases of coronary heart disease were documented. The researchers found that women in the highest quartile for soy protein intake were 75% less likely to develop coronary heart disease over the study period compared to women in the highest quartile for soy protein intake. The association between soy protein consumption and the risk of suffering a non-fatal myocardial infarction was even stronger with women in the highest quartile a massive 86% less likely to experience a non-fatal MI compared to those in the bottom quartile.

The risk of subsequently dying from coronary heart disease did not appear to be as strongly linked to soy protein intake however deaths from coronary heart disease were still lower amongst those who consumed high amounts of soy. Women in the highest quartile for soy protein intake were 27% less likely to die from coronary heart disease than those in the lowest quartile.

Women in the top quartile consumed an average of 1.99g of soy protein per 1000kj per day while women in the lowest quartile averaged 0.47g per 1000kj per day. Per capita consumption of soy protein in most western countries is below 1g per day. Japan, Korea, and parts of mainland China have the highest levels of soy protein intake in the world.

The authors concluded that: “Our study provides the strongest argument to date for the recommendation made by the American Heart Association to increase soy food intake to promote heart health.”

The full results of the study are presented in the graph below.

Graph of soy intake and coronary heart disease in women.

There are several mechanisms that are thought to explain the beneficial effects of soy on the heart. Soy protein is known to positively influence several risk factors for heart disease. Studies have shown a reduction in total cholesterol levels and LDL cholesterol levels, an increase in beneficial HDL cholesterol, and reduced blood pressure in individuals who consume large amounts of soy products.

One study, published in the American Journal of Clinical Nutrion in 2005, found that diets high in soy protein reduced total cholesterol levels by 3.8%, reduced LDL cholesterol levels by 5.25%, and increased LDL cholesterol levels by 3.0%.

Another study, also published in The American Journal of Clinical Nutrition, found that women who consumed 25g or more of soy protein a day had on average 1.9 mmHg lower systolic blood pressures and 0.9 mmHg lower diastolic blood pressures than women who consumed little or no soy.