Relative bioavailability of B-6 vitamers from cooked ground beef in humans

Abstract

The relative bioavailability of vitamin B-6 from cooked beef, supplemented with pyridoxal (PL) or pyridoxamine (PM), was investigated in two groups of healthy young men (age 22–35 years). The subjects were fed a controlled diet (2100–2500 kcal/day) for four days during the two test periods. After two days of controlled dietary intake, subjects ingested equimolar amounts of PL (5.98 μmol) or PM (5.95 μmol) in apple juice or cooked beef (176 0 C, 75 mins). After vitamin B-6 dosage, 24 hr urine samples were collected. In vitro assays revealed an increase in the irreversible binding (15–20%) of the [ 3H]B-6 vitamers to proteins in cooked beef extrinsically labelled with [ 3H]PL or [ 3H]PM compared to their respective controls in apple juice. There was no difference in the urinary excretion of 4-pyridoxic acid (4-PA) when subjects consumed the vitamin in apple juice or in cooked beef. Furthermore, urinary 4-PA excretion was not significantly different between the groups supplemented with PL or PM in the cooked test samples. In conclusion, vitamin B-6 from cooked beef appears to be highly bioavailable despite the increased irreversible binding of B-6 vitamers to proteinaceous components in beef.