- Dr. Kilmer McCully discovered in the 1960s that high levels of the amino acid homocysteine were linked to atherosclerosis and other diseases, but his work was rejected in favor of the cholesterol hypothesis. - Homocysteine was "rediscovered" as a risk factor for heart disease and other illnesses in the 1980s and 1990s through large studies finding associations with cardiovascular and other diseases. - Maintaining homocysteine levels below 9 μmol/L through diet and supplements can significantly reduce risks of heart disease, stroke, cancers, Alzheimer's, and early death.