Intestinal Absorption of Reduced Folate Compounds in Man

S ummary . Oral administration of folate compounds was followed by a rise in L. casei active factors in blood. This was due to reduction and methylation of the folate compounds in the small gut and this was demonstrated by the use of dihydropteroylglutamic acid labelled with tritium. Parenteral administration of tritium‐labelled folate analogues was followed by a rapid exchange with unlabelled L. casei active folate from tissues.