Description Biochem/physiol Actions End-product of oxidative metabolism of choline, betaine is a general methyl donor, in particular in a minor pathway of methionine biosynthesis. It is used to treat homocystinuria, which is a defect in the major pathway of methionine biosynthesis. Other Notes Download our Flavors and Fragrances Catalog to view our entire product line. Subscribe to our Newsletter to keep up to date on our latest Flavors and Fragrances offerings.