Vitamin B-6 Status during Childhood: Tracking from 2 Months to 11 Years of Age

To examine the development and tracking of long-term vitamin B-6 status from infancy to early adolescence, measurements of erythrocyte pyridoxal 5'-phosphate concentration (EPLP), the erythrocyte aspartate transaminase (EAST) stimulation test including measurements of basal activity (EAST o ) and activation coefficient (αEAST), were made in a follow-up study of healthy children aged 2 (n = 139), 4 (n = 147), 6 (n = 157), 9 (n = 159) and 12 mo (n = 188) and 5 y (n = 148). The EAST stimulation test was repeated at 11 y (n = 153). Vitamin B-6 status, high during infancy, reached the adult level by 5 y of age. The 10th to 90th percentile ranges for EPLP values were 61-201 nmol/L at 4 mo, 49-101 nmol/L at 12 mo and 27-59 nmol/L at 5 y. The respective ranges for EAST o were 16-24 μkat/L at 4 mo, 13-19 μkat/L at 12 mo, 9-14 μkat/L at 5 y and 25-39 μkat/L at 11 y of age. For αEAST values were 1.29-1.54 at 4 mo, 1.48-1.77 at 12 mo, 1.70-2.07 at 5 y and 2.00-2.57 at 11 y. Values for EPLP and the EAST stimulation test in the first year of life correlated with the values at 5 and 11 y. The individuals with values at the extreme ends of the distributions remained there from infancy to childhood up to 3.3 times more often than expected from random variation. Vitamin B-6 status, high in infancy, fell with age, and tracking of EPLP and EAST stimulation test values developed during the first year of life. The levels of these indices are affected by vitamin B-6 intake and age, but they may also be genetically influenced. Thus, the values for vitamin B-6 indices in infancy are predictive of the subsequent levels later in childhood.