S-adenosylmethionine (SAMe)

Figure 3 shows that S-adenosylmethionine (SAM, aka SAMe) is in the homocysteine-methionine pathway. SAM has been used in the treatment of liver disease, neurological disorders, rheumatoid arthritis (1), and fibromyalgia (2, 3). Houston et al. (4) noted that SAM is depleted in B12 deficiency. Loehrer et al. (1) reported that SAM levels are low in a significant proportion of coronary artery disease patients. Kelly (5) suggests that SAM is involved in converting cyanocobalamin to methylcobalamin.

Loehrer et al. (1) showed that 400 mg of SAM (in the form of S-adenosylcobalamin bis(sulfate)-p-toluenesulfonate) taken orally after an overnight fast (with the fast continuing for 6 more hours), caused serum SAM levels to increase substantially, indicating that SAM is absorbed when taken orally. It was well tolerated by all 14 volunteers.

Not enough research has been done to determine whether vegans who have depleted their stores of B12 can benefit from supplementing with SAM in addition to B12. Looking at the biochemical pathways, it would appear that if homocysteine levels are high (which would be expected in B12 deficiency) and folate is adequate, supplementing with B12 would be enough to replenish SAM stores. However, if supplementing with B12 does not resolve symptoms, someone might consider discussing SAM supplementation with their physician.


1. Loehrer FM, Schwab R, Angst CP, Haefeli WE, Fowler B. Influence of oral S-adenosylmethionine on plasma 5-methyltetrahydrofolate, S-adenosylhomocysteine, homocysteine and methionine in healthy humans. J Pharmacol Exp Ther. 1997 Aug;282(2):845-50.

2. Jacobsen S, Danneskiold-Samsoe B, Andersen RB. Oral S-adenosylmethionine in primary fibromyalgia. Double-blind clinical evaluation. Scand J Rheumatol. 1991;20(4):294-302.

3. Leventhal LJ. Management of fibromyalgia. Ann Intern Med. 1999 Dec 7;131(11):850-8.

4. Houston DK, Johnson MA, Nozza RJ, Gunter EW, Shea KJ, Cutler GM, Edmonds JT. Age-related hearing loss, vitamin B-12, and folate in elderly women. Am J Clin Nutr. 1999 Mar;69(3):564-71.

5. Kelly G. The co-enzyme forms of vitamin B12: Toward an understanding of their therapeutic potential. Alt Med Rev. 1997;2(5):459-471.