Well, I guess I'm one of those fortunate "fewer than 50%." When my cholesterol reached 230 my doctor told me what foods to cut and what foods to add. I was quite surprised to hear him tell me I needed to eliminate most meat and dairy from my diet and look toward a plant-life type of protein.
Medical research now has at least 40 years of evidence that shows positive benefits of soy protein in lowering cholesterol. One study I found dates back to 1967. Another study done in 1977 on a group of people with elevated cholesterol said that soy protein lowered cholesterol levels by 14% in two weeks and by 21% in three weeks.* And the studies seem to have been non-stop since then.
So how does the soy I've added to my diet lower my cholesterol? It's all about the amino acids. These are the chemicals or "building blocks" in our bodies that make up protein. There are twenty different types of amino acids and we humans produce ten of these in our bodies. The rest that we need we get from our food.
Certain amino acids change the levels of thyroid hormone (which regulates metabolism) and hormone insulin (which communicates with the liver about how we are being fed), which in turn controls cholesterol levels. When we eat foods such as chick peas, legumes and soybeans, which are high in the amino acids glycine and arginine, the insulin levels in our blood are lowered. It's the insulin that stimulates the liver to make cholesterol.
So you can see the simple chemical chain reaction here. When we take in the correct amino acids, like those found in soy, the insulin is lowered which helps keep the production of cholesterol lower.
An added note; proteins in meat are low with the amino acids glycine and arginine but high with one called lysine, which increases the insulin levels. Thus, the chain reaction of meat results in higher cholesterol. Meat proteins have the exact opposite effect on your body of the soy proteins.
*Agradi E, Conti F, Gatti E, Mantero O, Sirtori CR. Soybean protein diet in the treatment of type-II hyperlipoproteinaemia. Lancet. 1977; 5: 275-277.
