Hi SJB, Homocysteine. It's presence is associated with heart dieases, strokes, inflammation and all sorts of things. It's presence is caused by lack of mb12 and/or methylfolate and/or p5p. Prescriptions to reduce homocycteine such as Metanx (the best) contain methylb12, Metafolin and p5p. Older less effective ones contain cyanocbl, folic acid and b6.