Taking in extra soy or oats does not prevent heart attacks. I'm Dr. Gabe Mirkin on Fitness. Meta-analysis of the effects of soy protein intake on serum lipids. The most recent issue of the New England Journal of Medicine has an article that was reported to show that eating soy beans prevents heart attacks. James Anderson of the University of Kentucky reviewed other authors' studies on the effects of soybeans on cholesterol.
People tend to take in the same number of calories.
When you increase your intake of one food, you eat less of another. Several years ago, the same author published a paper that was reported to show that oatmeal prevents heart attacks. The same applies to oats. It's your total diet that counts. There are no good foods and there are no bad foods.