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Folate-binding protein and the absorption of folic acid in the small intestine of the suckling rat

Journal Article · · Am. J. Clin. Nutr.; (United States)
OSTI ID:7095404
The folate in milk is largely bound to high-affinity folate-binding protein (FBP). With an in vivo intestinal loop technique, we examined the absorption of folic acid bound to FBP (FA-FBP) in the small intestine of the suckling rat. In contrast to unbound folic acid (FA), FA-FBP is absorbed more avidly in the ileum than in the jejunum (p less than 0.025) and its absorption is not inhibited by 1 mmol sulfasalazine/L. Folate-binding activities in the mucosa of the proximal (duodenum and jejunum combined) and distal (ileum) small intestine were also examined and found to be 0.32 and 1.31 pmol/mg protein, respectively (p less than 0.001). A 6-h fast produced a 42% decrease in folate-binding activity in the distal small intestine (p less than 0.01) but did not change activity in the proximal portion. Collectively, these observations suggest that FA-FBP is absorbed by a mechanism that is distinct from that responsible for the absorption of FA and that absorption does not require prior dissociation of the vitamin-binding protein complex.
Research Organization:
Univ. of Chicago, IL (USA)
OSTI ID:
7095404
Journal Information:
Am. J. Clin. Nutr.; (United States), Journal Name: Am. J. Clin. Nutr.; (United States) Vol. 48:3; ISSN AJCNA
Country of Publication:
United States
Language:
English