Carnitine intake is associated with better postnatal growth and larger brain size in very preterm infants

Carnitine is a compound similar to amino acids, and its primary function in the body is to transport long-chain fatty acids to the cell powerhouse mitochondria for energy production. In addition, earlier studies have suggested that carnitine may also be involved in nervous system development. Carnitine is both obtained from nutrition and produced by the body. In preterm infants, the main sources of carnitine are breast milk and infant formulae containing carnitine.

Very preterm infants have an increased risk for developing carnitine deficiency

"Very preterm infants born before 32 weeks of gestation are at risk of developing carnitine deficiency due to limited tissue stores, immature endogenous synthesis, and insufficient intake from nutrition. Due to rapid growth, they also have an increased need for carnitine," says Postdoctoral Researcher Suvi Manninen of the University of Eastern Finland.

The associations of carnitine intake and serum carnitine levels with the growth and brain size of preterm infants have not been studied in a longitudinal setting before. In this new study, the researchers measured the carnitine levels of preterm infants at three time points and calculated the intake of nutrients, including carnitine, over the first five postnatal weeks. The researchers examined the associations of serum carnitine levels and nutrition with the growth of weight, length and head circumference, as well as brain diameters determined by magnetic resonance imaging.

The intake of carnitine, and free carnitine and short-chain acylcarnitine concentrations in serum, were associated with the growth of preterm infants and with cerebellar size in particular. In addition to these associations, dietary carnitine was found to correlate with free carnitine and short-chain acylcarnitine concentrations in serum, suggesting that these carnitine levels can be considered markers of carnitine intake.

Is carnitine supplementation necessary?

"Both breast milk and infant formulae contain varying amounts of carnitine. Parenteral nutrition, i.e., nutrient preparations given intravenously, on the other hand, usually do not contain carnitine," says Adjunct Professor, Neonatologist Ulla Sankilampi from Kuopio University Hospital.

It is possible to give carnitine parenterally, but evidence on the benefits of carnitine supplementation remains contradictory and it is not generally recommended in the current parenteral nutrition guidelines for preterm infants.

"Further research is still needed on whether carnitine supplementation is necessary during prolonged parenteral nutrition and, on the other hand, whether breast milk should be enriched with carnitine in some situations in the dietary treatment of preterm infants."