Methylmethionine Sulfonium Chloride Vitamin U Supplement Methylmethionine sulfonium chloride supplement is a term introduced in the early 1950s to identify a compound in cabbage juice. Examples of methionine derivatives often called vitamin U Supplement include S methylmethionine supplement (SMM), methylmethionine sulfonium (SMM), and 3-amino-3-carboxypropyl dimethylsulfonium.
Methylmethionine sulfonium chloride vitamin U Supplement is available not only as a supplement but also found naturally in various foods, particularly cruciferous vegetables like cabbage, broccoli, Brussel sprouts, and kale (1Trusted Source).