SCIENCE REPORT- Soy Reduces CholesterolBy Nancy Steinbach
This is the VOA Special English SCIENCE REPORT.
The American Heart Association says that eating soy protein can improve the health of people with high levels of cholesterol in their blood. Its new statement follows studies showing that soy protein can help reduce the chance of developing heart disease.
John Erdman is a professor of food science and human nutrition at the University of Illinois in Urbana. He wrote the American Heart Association statement. It was published in The Association journal, "Circulation".
It says studies have shown that eating twenty-five to fifty grams of soy protein every day is a safe and effective way to reduce harmful cholesterol by up to eight percent. The greatest effects were seen in people with high cholesterol levels.
The statement also says that eating soy protein has little effect on people with normal cholesterol levels. So there is no danger that people with low cholesterol can reduce it too much by eating soy.
Heart disease is a major public health concern in many industrial countries. It causes more deaths in the United States than any other disease. Studies show an increased risk for heart disease in people with high total cholesterol levels and high levels of low-density lipoprotein cholesterol.
Soybeans and soybean products are the main source of protein for millions of people in Asia. People in that part of the world have been eating soy products since ancient times. Experts say the soybean probably was first grown in eastern China. Studies show that Asians have much lower rates of heart disease than Americans or Europeans.
Medical researchers say one reason soy protein reduces cholesterol is because it contains substances called isoflavones. Isoflavones are produced by plants. They are called phytoestrogens because they are like the hormone estrogen. Estrogen improves cholesterol levels. Phytoestrogens are thought to have a similar, but weaker, effect. Studies in humans have shown that soy protein with isoflavones lowered cholesterol more than soy protein without isoflavones. Researchers say both soy protein and isoflavones may be needed to produce the cholesterol-lowering effect.
Foods high in these substances include soy milk, tofu, and products made with soy flour.
This VOA Special English SCIENCE REPORT was written by Nancy Steinbach.