Polyunsaturated fatty acids: Metabolism and nutritional requirements in pregnancy and infancy

Omega-3 long chain polyunsaturated fatty acids (n-3 LCPUFAs), in particular docosahexaenoic acid (DHA), are essential for optimal development of the fetus, especially the brain, nervous, and visual systems. The fetus has a limited capacity to synthesize eicosapentaenoic acid (EPA) and DHA, and therefore relies almost exclusively on EPA/DHA transferred across the placenta from the maternal circulation. Failure to accumulate sufficient n-3 LCPFUA during the last trimester of pregnancy has long-term impacts on developmental outcomes, and growth-restricted and preterm infants are at highest risk of early DHA deficits. Besides maternal dietary DHA intake, placental metabolism and n-3 LCPUFA transfer, biomagnification, fetal synthesis, and metabolism, also play an important role in determining fetal DHA (and EPA) concentrations. However, while an adequate supply of n-3 LCPUFA is essential for fetal and infant growth and development, there is limited evidence that supplying additional n-3 LCPUFA to mothers during pregnancy or to term infants who are not overtly deficient has any additional benefits for cognitive, visual, or metabolic outcomes in the infant.