Homocysteine is simply an amino acid. The body produces this amino acid usually as a byproduct from meat consumption. Having too much of this amino acid is a good indication that you may be at risk for a heart attack or a stroke. In elderly people, an elevated homocysteine level has been linked to brittle bones in elderly people.
Folate and vitamin B12 have been shown to help lower the homocysteine levels but there are more studies needing to be done. For now the best hope is to prevent and then reduce levels once they are elevated. Levels can be reduced with a change to diet and supplementation.
The best way to prevent the problems related to elevated homocysteine is to get annual tests of this amino acid. If you have a family history of high homocysteine levels, semi-annual testing may be recommended. You can get a test at TestMeHealth.com that will test you for this amino acid.