Scientists believe one of those factors is a substance called homocysteine. Atherosclerosis, the accumulation of plaque in the arteries, accounts for more than 1.5 million heart attacks and 600,000 strokes every year in the U.S., Hodis says. A variety of factors, including the amount and type of fat in the diet, blood cholesterol levels, exercise habits, smoking and heredity, contribute to the build-up of fatty deposits in the arteries.
Doctors also monitor trigylceride levels in the blood.
But Hodis and colleagues are looking for more answers. And homocysteine is a promising one. When a person eats proteins in food, the body processes the proteins to extract an important amino acid, called methionine. Certain chemical reactions in the body help get rid of homocysteine through urine or recycle it back into methionine through the liver. But if homocysteine accumulates in the body, it is thought to become toxic to arteries and contribute to the formation of atherosclerotic plaque.