The effect of three intravenous fat emulsions containing different concentrations of linoleic and alpha-linolenic acids on the plasma total fatty acid profile of neonates

Influence of different intravenous lipid emulsions on growth, development and laboratory and clinical outcomes in hospitalised paediatric patients: A systematic review

BACKGROUND & AIMS

Fats in the form of lipid emulsions (LEs) are an integral part of intravenous nutrition. The fatty acid composition of different LEs varies. The exact composition of a LE may influence cell and tissue function and clinical outcome. Currently, it is not clear which LE might be best for paediatric patients. We conducted a systematic review of the effects of different intravenous LEs in hospitalised paediatric patients.

METHODS

Randomised controlled trials published in a peer reviewed journal, written in the English language, and comparing two or more different intravenous LEs in hospitalised paediatric patients were included. Data on outcomes of relevance (growth, development, laboratory and clinical outcomes) were extracted, collated and interpreted.

RESULTS

Thirty-one articles involving 1522 infants or children were included. Most outcomes were not affected by the nature of the LE used. LEs containing fish oil, a source of omega-3 fatty acids, improved outcome of retinopathy of prematurity, decreased liver cholestasis and increased blood omega-3 fatty acid levels. LEs containing olive oil increased blood oleic acid level and had a cholesterol lowering effect.

CONCLUSION

Blood fatty acids are influenced by the nature of the intravenous LE used in hospitalised paediatric patients. Most studies suggest limited differences in relevant laboratory or clinical outcomes or in growth in paediatric patients receiving different LEs, although several studies do find benefits from including fish oil or olive oil. There is a need for larger trials to fully evaluate the effects of the available LE types in hospitalised paediatric patients.

Essential fatty acid metabolism and requirements for LBW infants

Humans are unable to synthesize linoleic acid (LA) (18:2 omega-6) and alpha-linolenic acid (LNA) (18:3 omega-3). Most formulas provide ample LA, yet infants are at risk for omega-3 deficiency unless they are fed human milk. Neonates born at 30 weeks received human milk or were randomized to three formulas: formula A, based on corn oil, similar to old commercial formula; formula B, based on soy oil supplied LNA; or formula C, a product similar to B with added marine oil to provide docosahexaenoic acid (22:6 omega-3). The fatty acids of plasma and red blood cells had marked diet-induced differences. The rod photo-receptor tests demonstrated higher threshold and decreased sensitivity in the omega-3-deficient infants. Visual acuity also showed improved function of the brain cortex in the human milk and group C infants at follow-up at 57 weeks. These results suggest that omega-3 fatty acids are needed for optimal development of visual function.

Effect of three intravenously administered fat emulsions containing different concentrations of fatty acids on the plasma fatty acid composition of premature infants

The effects of an intravenously administered lipid emulsion supplemented with gamma-linolenic acid on the fatty acid profile of premature infants were compared with those of two conventional lipid emulsions. Fifty-nine premature neonates receiving total parenteral nutrition were randomly assigned to receive either fat emulsion containing gamma-linolenic acid and long-chain triglycerides (LCT), an LCT emulsion, or a 50% (wt/wt) mixture of medium-chain triglycerides and LCT emulsion. Forty-nine infants completed the study. During the 6-day study there was a significant tenfold increase in the plasma levels of gamma-linoleic acid in the supplemented group versus the other two groups. A significant threefold to fivefold increase in the omega 6 long-chain polyunsaturated fatty acids was observed in all groups. These changes seemed to be attributable mostly to linoleic acid from the lipid emulsion, despite the 50% lower dose in the medium- and long-chain triglycerides group. The increase in the omega 3 long-chain polyunsaturated fatty acids also was mainly caused by a similar increase in the level of alpha-linolenic acid. No differences were recorded in the linoleic/alpha-linolenic acid ratio among the groups. Plasma levels of some of the semiessential fatty acids were significantly higher in the medium- and long-chain triglycerides group than in the LCT group. This may be related to slower elimination of LCT, to the difference between emulsions, or to less substrate inhibition on delta-6-desaturase, which seems to be less of a rate-limiting enzyme than previously considered. Further intravenous feeding trials are needed to identify the optimal balance of fatty acids for nutrition of these premature infants.