Purpose of review: Lipid emulsions are crucial for providing essential fatty acids and energy in infants and children requiring parenteral nutrition. There is ongoing debate about the optimal composition of lipid emulsions and the optimal timing for introducing lipids to the parenteral nutrition of premature infants in order to enhance the benefits and to minimize the risk of complications.
Recent findings: Several studies have investigated the effects of early compared with late administration of lipid emulsions. A meta-analysis demonstrated that early introduction of lipid emulsions does not improve short-term growth or prevent morbidity and mortality in preterm infants. On the other hand, early introduction of lipid emulsions was not shown to increase the risk of complications. A number of studies have investigated the effects of different fatty acid compositions in lipid emulsions on peroxidation. In-vitro findings suggest that lipid peroxidation is related to the polyunsaturated fatty acid content and inversely related to the alpha-tocopherol/polyunsaturated fatty acid ratio of the fat emulsion. The composition of lipid emulsions has also been shown to influence fatty acid metabolism. A mixture of medium-chain and long-chain triglycerides seems to enhance the incorporation of essential fatty acids and long-chain polyunsaturated fatty acids into circulating lipids when compared with an emulsion containing only long-chain triglycerides.
Summary: Although the composition of lipid emulsions has been demonstrated to influence peroxidation and fatty acid metabolism, outcome studies are needed to confirm advantageous effects.