CAS 3211-76-5 L-Selenomethionine L-SeMet For Dietary Supplements And Animal Nutrition Product Description L-Selenomethionine Description L-Selenomethionine is the selenium analogue of the essential amino acid L-methionine, where a selenium atom replaces the sulfur atom. It serves as a primary organic source of selenium in biological systems and is considered the most bioavailable form of selenium for humans and animals. In nature, it is synthesized by plants and microorganism