Homocysteine is an amino acid. Vitamins B12, B6 and folate break down homocysteine to create other chemicals your body needs. High homocysteine levels may mean you have a vitamin deficiency. With a High homocysteine doesn't usually cause symptoms on its own, but it can signal vitamin deficiencies or other health issues and it's something you can check with a simple blood test Homocysteine, B vitamins, and risk of cardiovascular disease Heart Glutathione reduces homocysteine levels