Plasma concentrations of N-acetylneuraminic acid in severe malnutrition

In rat studies, circulating concentrations of N-acetylneuraminic acid (NANA) have been shown to be an indicator of NANA concentrations in the brain and functional brain activity, in relation to nutritional state and stimulation. Abnormal behaviour can be improved with exogenous NANA. In the present study, the plasma NANA concentration has been measured in children with severe malnutrition and compared with that in controls. NANA was measured colorimetrically in the plasma of twenty-three severely malnourished children (mean age 11.43 (SD 6.05) months) before and after recovery, and in thirty-four controls (mean age 14.28 (SD 7.32)months). In thirteen of the malnourished children, NANA was measured after infections had been treated with a course of antibiotics. Mean plasma NANA concentration was significantly higher in protein-energy malnutrition (PEM) (2.89 (SD 0.58) mumol/ml; n 23) compared with controls (2.13 (SD 0.37) mumol/ml; n 34, P less than 0.001). The levels remained high in PEM after infections had been treated (2.87 (SD 0.43) mumol/ml, n 13) but returned to control levels at recovery from PEM (2.14 (SD 0.24) mumol/ml). In contrast to the findings in rats, in malnourished children plasma NANA concentrations were not reduced and did not relate directly to nutritional state or, by inference, brain function. These findings do not provide any support for the use of exogenous NANA supplements to improve brain function in humans.