Hello Thanks for writing to HCM Patients experiencing an insufficiency in their intrinsic factor levels cannot benefit from a low dose oral vitamin B12 supplement, because it will not absorb through the wall of the small intestine.Unlike other water-soluble vitamins, vitamin B12 is stored in the liver. The high dose of vitamin B12 thus ingested allowed enough of it to be taken up passively. As more and more potent liver extracts became available this repugnant treatment became unnecessary, improving the life quality of the patients. Today synthetic vitamin B12 is injected monthly, thus bypassing the digestive tract altogether. More recently, Swedish researchers discovered that sufficiently large doses of B12 can also be absorbed sublingually, removing the necessity for injectable B12.[2] However, no standards have been set for treatment by the sublingual route yet, and injections of B12 are the only reliable method of treatment. Discuss this with your doctor and then decide Hope this helps Take Care.