Introduction: Fatty acids (FA) play an important role in growth and cellular metabolism. The ratio of unsaturated (mono- and polyunsaturated) to saturated fatty acids influences normal growth, brain development and susceptibility to infections. The fetus is entirely dependent on maternal supply for the essential FA (polyunsaturated). Determination of tissue lipid composition is therefore crucial for optimal nutritional support in premature infants.

Objective: To determine the ratio of unsaturated to saturated FA in human tissue at different stages of development. To guide nutritional support for optimal conditions for brain development.

Design/Methods: Preterm and fullterm infants unremarkable with respect to neurological and medical status were studied by 13C MRS within the first week of life. Natural abundance 13C MRS was performed on neonatal adipose and muscle tissue using a specially designed surface coil. Ratios of unsaturated to saturated fatty acids and percentages of polyunsaturated fatty acid were determined by calculation of peak heights (linewidth identical for resonances involved) in the fully relaxed spectrum(1).

Results: Initial results show marked differences in the distribution of fatty acids in newborns of various GA compared to adults. Total unsaturated fatty acids measured in young adults accounted for 60% of all FA (40% monounsaturated, 20% polyunsaturated) which is in agreement with other authors(1,2). In fullterm infants total unsaturated FA accounted for 55% of all FA, with a similar distribution of mono- to polyunsaturated ratio. In preterm infants (32wk/35wkGA) the proportion of unsaturated FA was lower (44%/46%)

Conclusion: Natural abundance 13C-MRS allows in vivo measurement of unsaturated (mono- and polyunsaturated) FA, which have been shown to be important in early brain development(3). Preterm infants have a lower percentage of unsaturated FA shortly after birth. This raises the possibility of a need for higher supplementation of these essential FA in preterm infants.