Detection of a milk factor that facilitates folate uptake by intestinal cells.

Folate binding proteins in milk were tested for their effect on folate absorption. The uptake of bound folate by isolated mucosal cells from the rat small intestine was twice that of free folate and differed from it in being more effective with progression down the small intestine, in not being affected by glucose or Dilantin, in having a higher pH optimum, and in being affected by calcium concentration. This milk factor may enhance folate absorption in infants, whose risk of folate deficiency is high.