Apparent deficiency of vitamin B6 in typical individuals who commonly serve as normal controls.

Individuals who typically serve as normal controls were found by the differential assay of the glutamic oxaloacetic transaminase in their erythrocytes to have a deficiency (P less than 0.001) of enzyme activity as well as a deficiency (P less than 0.001) of pyridoxal phosphate. Contrary to the understanding that the diet provides an adequate intake of vitamin B6, the dietary intake of vitamin B6 of these controls was inadequate.