Homocysteine Homocysteine is a common amino acid found in our blood, and a homologue to cysteine. First discovered in 1932 by Butz and Vigneaud, and eventually identified for its role in promoting arteriosclerosis in 1969 (McCully, 2004). New studies in 2016 and 2017 are now linking high levels of homocysteine to degenerative brain disorders, and other illnesses ( (Refsum & Smith, 2017). As we age, our ability to enzymatically metabolize and absorb folic acid is compromised,