A recent report in the New England Journal of Medicine was reported in the media to show that eating soybeans prevents heart attacks. The study showed no such results. However, there is no evidence that soy protein lowers cholesterol.
Most people eat the same number of calories each day.
So when you increase your intake of one food, you often decrease your intake of another to keep your caloric intake constant. Therefore, people who increase their intake of soy usually reduce their intake of meat, fish and chicken. We have known for more than 60 years that animal protein raises cholesterol far more than plant protein does. So, it is the reduction of animal protein, rather than the increase of soy protein that lowers cholesterol. Several years ago, the same author published a paper showing that people who eat oat bran also have lower blood cholesterol levels.