Human vitamin B-6 pools estimated through muscle biopsies.

Previous estimates of total vitamin B-6 pools in humans based on extrapolations from tracer studies yielded values of 107-190 mumol when the tracer was administered orally and 345-725 mumol when the tracer was administered intravenously. To obtain a more direct estimate of vitamin B-6 pools, muscle biopsies from five female and seven male adults were analyzed by cation-exchange chromatography. Total muscle mass was estimated from creatinine excretion and the assumption that muscle is 40% of the body weight. The total muscle vitamin B-6 pool was estimated to be 917 +/- 319 mumol in the females and 850 +/- 216 mumol in the males. Because muscle accounts for approximately 80% of the vitamin B-6 in the body, the total body pool of vitamin B-6 in adult humans is probably approximately 1000 mumol.