Abstract
Recent data revealed differences in human absorption kinetics and metabolism between food folates and folic acid supplements and fortificant. 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. 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. 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). 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.
Highlights
Good folate status is associated with a number of health benefits
The only labeled folate form that exceeded the limit of detection in postdose plasma was [13C5]5-CH3-H4 folate after ingestion of [13C5]5-CH3-H4 folate and [13C5]folic acid
Because the concentrations of folic acid and H4 folate in plasma samples were around the limit of quantification (1 nmol/L), only unlabeled 5-CH3-H4 folate concentrations were used for calculations
Summary
Good folate status is associated with a number of health benefits. mandatory fortification of staple foods with synthetic folic acid has been introduced in several countries to compensate for folate intakes below the recommended intake (1). Recent data in humans revealed differences in absorption kinetics and metabolism between (mainly reduced) food folates and folic acid supplements or fortificant (2). Recent data revealed differences in human absorption kinetics and metabolism between food folates and folic acid supplements and fortificant. Results: The median (range) plasma AUC0/12 (AUC from 0 to 12 h after ingested dose) of 66 nmol Á h/L (34–84 nmol Á h/L) after ingestion of bread that contained (6S)-[13C5]5-CH3-H4 folate was significantly greater (P , 0.001) than that after ingestion of [13C5] folic acid in fortified bread [28 nmol Á h/L (15–38 nmol Á h/L)] and a fortified breakfast meal [26 nmol Á h/L (15–60 nmol Á h/L)].
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