Glycine production in severe childhood undernutrition

Although nutritionally dispensable amino acids are not essential in the diet, from a biochemical standpoint, dispensable amino acids such as glycine are essential for life. This is especially true under unique circumstances, such as when the availability of labile nitrogen for dispensable amino acid synthesis is reduced, as in severe childhood undernutrition.

We aimed to measure glycine production in children with edematous and nonedematous severe childhood undernutrition.

Glycine flux and splanchnic glycine extraction were measured in 2 groups of children with edematous (n = 8) and nonedematous (n = 9) severe childhood undernutrition when they were infected and malnourished (clinical phase 1), when they were still severely malnourished but no longer infected (clinical phase 2), and when they were recovered (clinical phase 3).

Total and endogenous glycine flux and splanchnic glycine uptake did not differ significantly between the edematous and nonedematous groups during any clinical phase. In both groups of subjects, none of the glycine kinetic parameters changed significantly from clinical phase 1 through phases 2 and 3. Compared with the value at clinical phase 3, plasma glycine concentrations were not significantly lower during clinical phase 1 or 2 in either group.

These findings suggest that children with severe childhood undernutrition can increase their de novo glycine synthesis to compensate for the reduced contribution from chronic food deprivation. The maintenance of the plasma glycine concentration suggests that the rate of glycine production was sufficient to satisfy metabolic demands in these children when they were acutely undernourished and infected.