Sublingual B-12 MC by Foodscience Of Vermont.80% of Vitamin B12 in the plasma is in the methylcobalamin form, Methylcobalamin is the active form of B12. Sublingual B12-MC is absorbed through the oral mucosal thus by-passing the need for the intrinsic factor in the stomach. This is especially important for the elderly as the intrinsic factor declines with age. B12 also benefits vegetarians who are often deficient due to dietary inadequacy.