HOMOCYSTEINE an amino acid that is from the breakdown of protein metabolism. When present in high concentrations, has been linked to an increased risk of heart attacks and strokes. Blood levels of homocysteine are highest in people who eat a lot of animal protein and consume few fruits and leafy vegetables, which provide the folic acid and other B vitamins that help the body rid itself of homocysteine. Eating fatty animal proteins and drinking caffeine products are the main sources of increased homocysteine.