MethylAssistWith Metafolin L 5 MTHF Supports nutrient metabolism Contributes to the formation of red blood cells MethylAssist provides activated B vitamins, including Metafolin L 5 methyltetrahydrofolate (L 5 MTHF), to support nutrient metabolism. Activated B vitamins are particularly important for their contribution of methyl groups participating in the methylation cycle. Methylation involves the transfer of a methyl group (CH3) from one molecule to another.