|This paper starts with a review of the metabolism of n-6 (omega6) and n-3 (omega3) fatty acids, the resulting eicosanoids (prostaglandins, leucotrienes, and thromboxanes), and the physiological functions they are involved in, with special emphasis on effects during pregnancy (such as possible benefits on fetal growth, prevention of hypertension of pregnancy, and prevention of premature labor).
Attention is then turned to the key role for long-chain polyunsaturated fatty acids (LCPUFAs), most notably docosahexaenoic acid (DHA), in central nervous system and retinal cell membrane structure and in cerebral and retinal development.
Massive maternofetal transfer of LCPUFAs occurs during the third trimester of pregnancy, so that maintaining an adequate intake of DHA during pregnancy is crucial. Preterm babies must receive sufficient amounts of DHA, either via breast milk or via formula supplemented with LCPUFAs, both of which prevent DHA levels from declining in blood and cerebral phospholipids. These two methods of achieving an adequate DHA intake ensure normal maturation of visual acuity and cognitive function, as shown by randomized controlled trials.
Formula supplemented with fish oils rich in n-3 LCPUFAs but lacking a proportionate supply of arachidonic acid (ArA, 20: 4n-6) negatively affects somatic growth, confirming the need for an adequate ArA supply. Eicosapentaenoic acid (EPA) can also exert negative effects.
Therefore, the best source of supplemental LCPUFAs may be oil from single-cell algae and microscopic fungi, which contains adequate amounts of DHA and ArA.
In full term neonates, strong arguments support LCPUFA supplementation, despite continuing controversy generated by conflicting results from interventional studies. These discrepancies in study results may be ascribable to differences in study design, patient age, intervention duration, assessment tool sensitivity, and LCPUFA sources. In 1996, an amendment to the European Directive on infant formulas and follow-on formulas was developed to authorize LCPUFA supplementation and to specify appropriate ranges.
As a result, formulas supplemented with DHA and ArA were introduced on the market. Pregnant and nursing women should be advised to maintain an adequate dietary intake of DHA in order to meet their increased needs and those of the fetus or infant.