A substance called homocysteine can be found in trace amounts in your blood. The homocysteine in your body is broken down into other molecules by the vitamins B6, B9, and B12. Your blood should contain very little homocysteine after this process. However, if the process isn't operating correctly, your homocysteine level could be elevated. Your chance of developing cardiovascular disorders such as coronary artery disease, heart attack and atherosclerosis might rise as a result of homocysteine buildup in your blood vessels.