Since high levels of homocysteine are associated with an increased risk for atherosclerosis, diabetic heart disease, heart attack, and stroke, it's a good idea to be sure that your diet contains plenty of vitamin B12 to help keep homocysteine levels low (homocysteine is also associated with osteoporosis, and a recent study found that osteoporosis occurred more frequently among women whose vitamin B12 status was deficient or marginal compared with those who had normal B12 status.)