Folate bioavailability from breads and a meal assessed with a human stable-isotope area under the curve and ileostomy model.
BACKGROUND
Recent data revealed differences in human absorption kinetics and metabolism between food folates and folic acid supplements and fortificant.


OBJECTIVE
The objective was to determine folate bioavailability after ingestion of breads or a breakfast meal fortified with either 5-CH(3)-H(4) folate or folic acid by using a stable-isotope area under the curve (AUC) and ileostomy model.


METHODS
In a randomized crossover trial, healthy ileostomists (n = 8) ingested single doses of whole-meal bread that contained ap 450 nmol (200 micro g) of either (6S)-[(13)C(5)]5-CH(3)-H(4) folate or [(13)C(5)]folic acid or a breakfast meal that contained ap 450 nmol (200 micro g) [(13)C(5)]folic acid. We collected blood from the subjects during 12 h postdose for assessment of plasma kinetics. Nonabsorbed folate was assessed from labeled folate contents in stomal effluent 12 and 24 h postdose.


RESULTS
The median (range) plasma AUC(0 rarr 12) (AUC from 0 to 12 h after ingested dose) of 66 nmol sdot h/L (34-84 nmol sdot h/L) after ingestion of bread that contained (6S)-[(13)C(5)]5-CH(3)-H(4) folate was significantly greater (P lt 0.001) than that after ingestion of [(13)C(5)]folic acid in fortified bread [28 nmol sdot h/L (15-38 nmol sdot h/L)] and a fortified breakfast meal [26 nmol sdot h/L (15-60 nmol sdot h/L)]. Both labeled doses resulted in increases of plasma [(13)C(5)]5-CH(3)-H(4) folate. However, the kinetic variables C(max) (maximum plasma concentration) and T(max) [time (min) of maximum plasma concentration] varied after ingestion of the different folate forms. The stomal folate content was lt 10% of the ingested dose and did not vary significantly after ingestion of test foods that contained (6S)-[(13)C(5)]5-CH(3)-H(4) folate [median (range): 13 nmol (10-31 nmol)] or [(13)C(5)]folic acid [median (range): 25 nmol (8-42 nmol)] (P = 0.33).


CONCLUSIONS
Our data confirm differences in plasma absorption kinetics for reduced folates and synthetic folic acid administered with the test foods. Stomal folate contents indicated almost complete bioavailability of labeled folate from the breads or breakfast meal.
Ohrvik
Veronica E
VE
Department of Food Science, Swedish University of Agricultural Sciences, Uppsala, Sweden. veronica.ohrvik@lmv.slu.se
Büttner
Barbara E
BE
Rychlik
Michael
M
Lundin
Eva
E
Witthöft
Cornelia M
CM
D000328:Adult; D000368:Aged; D019540:Area Under Curve; D001682:Biological Availability; D001939:Bread / Q000032:analysis; D018592:Cross-Over Studies; D004032:Diet; D002523:Edible Grain; D005260:Female; D005492:Folic Acid / Q000097:blood / Q000493:pharmacokinetics*; D005527:Food, Fortified; D006801:Humans; D007081:Ileostomy; D007408:Intestinal Absorption; D007553:Isotope Labeling; D008297:Male; D008875:Middle Aged
D005492:Folic Acid