Portal and peripheral plasma folates after ingestion of folic acid

Folic acid in amounts of 2 mumol (0.88 mg) was given by mouth to four patients who had undergone portal vein catheterization. All had normal liver function. The increase in folates in plasma obtained from portal and peripheral veins was followed for three hours with the use of L. casei and S. faecalis as test organisms. The results lend support to the assumption that the liver is the main site of methylation of folic acid when given in physiological amounts.