Bioavailability of vitamin B-6 from rat diets containing wheat bran or cellulose.
Bioavailability of vitamin B-6 (B-6) in the total diet was studied in male, weanling Sprague-Dawley rats fed fiber-free (FF) diets with 0.2 or 6.9 mg pyridoxine/kg diet (0-, 2- or 6.9-PYR), 20% wheat bran (WB) diets with 3.9- or 5.5-PYR or 7% cellulose (C) diets with 0- or 2-PYR for 28 d. Body weight gain (mean +/- SEM) with 0-PYR was 70 +/- 9.0 and 81.2 +/- 4.2 g for FF and C, respectively. All other groups gained 170-180 g. Urinary excretion of 4-pyridoxic acid (4-PA), a major B-6 metabolite, for FF groups was 1.31 +/- 0.22, 2.26 +/- 0.28 and 6.39 +/- 1.73 micrograms/24 h, at 0-, 2- and 6.9-PYR, respectively. Rats fed WB diets excreted 4.99 +/- 0.58 and 9.81 +/- 0.76 micrograms/24 h (3.9- and 5.5-PYR, respectively) and those fed C diets excreted 1.46 +/- 0.34 and 2.69 +/- 0.72 micrograms/24 h (0- and 2-PYR). There was increasing turnover and shorter biological half-life of [14C]pyridoxine (1 mu Ci injected on d 1) with increasing dietary B-6. Growth, 4-PA and 14C turnover data indicated that WB contributed to B-6 intake of these rats. Cellulose acted as a simple dietary diluent and had no effect on indices of B-6 status. These data suggest that dietary fiber, as cellulose or the indigestible component of wheat bran, does not adversely affect the bioavailability of vitamin B-6.
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U.S. Department of Agriculture, Western Regional Research Center, Albany, CA 94710.
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D000818:Animals; D001835:Body Weight; D002244:Carbon / Q000378:metabolism; D002250:Carbon Radioisotopes; D002482:Cellulose; D004043:Dietary Fiber / Q000008:administration & dosage*; D004435:Eating; D008099:Liver / Q000378:metabolism; D008297:Male; D009753:Nutritive Value; D011735:Pyridoxic Acid / Q000652:urine; D011736:Pyridoxine / Q000493:pharmacokinetics*; D051381:Rats; D011919:Rats, Inbred Strains; D014908:Triticum
D002250:Carbon Radioisotopes; D004043:Dietary Fiber; D011735:Pyridoxic Acid; D002244:Carbon; D002482:Cellulose; D011736:Pyridoxine