Intestinal absorption of S-adenosyl-L-methionine.

The gastrointestinal absorption of S-adenosyl-L-methionine (SAMe) is demonstrated by evaluating plasma levels and gastrointestinal content of the unmodified molecule after oral administration. When [methyl-14C]SAMe is given orally, the radioactivity found in the liver is associated both with SAMe and phosphatidylcholine, a compound known to be derived from the methylation of phosphatidylethanolamine with SAMe as a methyl donor. These results and low plasma levels after the oral administration may be suggestive of a first-pass effect of SAMe characterized by an extensive uptake of the drug by the liver where it is rapidly metabolized.