Depressed plasma pyridoxal phosphate concentrations in adult asthmatics

In 15 adult patients with bronchial asthma, plasma and erythrocyte pyridoxal phosphate (PLP) concentrations were significantly lower than in 16 controls (P less than 0.0001 and P less than 0.005, respectively). Oral supplementation of seven asthmatics with 50 mg pyridoxine as pyridoxine X HC1 twice daily failed to produce a sustained elevation of PLP in either the plasma or erythrocytes. However, all subjects reported a dramatic decrease in frequency and severity of wheezing or asthmatic attacks while taking the supplement. The reasons for the failure of a uniform elevation in plasma and erythrocyte PLP concentration and for the apparent beneficial effects of pyridoxine supplementation on the asthmatic symptoms of the patients are unknown at present.