Plasma vitamin B6 concentrations in Nigerian adolescents

Vitamin B6 status was assessed from dietary and plasma vitamin B6 concentration using Saccharomyces uvarum as test organism, and erythrocyte alanine amino transferase activity (E-ALAT). The subjects participating in the study were 72 males and 30 females (aged 10-18 years) who resided in a boarding institution. Mean daily dietary vitamin B6 and protein intakes were 1.56 +/- 0.42 mg and 63.0 +/- 9.6 g respectively. The corresponding mean plasma vitamin B6 concentration was 194 +/- 44.2 nmol/l. Neither age, sex nor menarche had significant effect (P less than 0.05) on plasma vitamin B6 concentration of these adolescents. Dietary vitamin B6 but not protein intake correlated with plasma vitamin B6 (r = 0.3076, P less than 0.002). However, low dietary vitamin B6/protein ratio (less than 0.02 mg/g) was not reflected in plasma vitamin B6 concentration, but low plasma vitamin B6 concentration (120-179 nmol/l) corresponded to low E-ALAT activity after in vitro addition of pyridoxal phosphate (E-ELAT 16 per cent). A stimulation above 25 per cent, 16-25 per cent and below 16 per cent was used as an indicator of poor, marginal and adequate vitamin B6 status, respectively. Based on these criteria 30.7 per cent, 17.8 per cent and 51.5 per cent of subjects, with corresponding mean plasma vitamin B6 of 150 +/- 28.4, 192 +/- 8.5 and 237 +/- 18.7 nmol/l are of deficient, marginal and adequate vitamin B6 status, respectively.