Long-chain polyunsaturated fatty acids with 20 and 22 carbon atoms (LC
Ps) seem to play an important role during the rapid development of the
infant brain in the late fetal and early postnatal period. These LCPs
are integral constituents of biological membranes and they are involv
ed in the regulation of functional properties like fluidity, permeabil
ity and activity of membrane-bound enzymes. Human milk contains LCPs i
n an amount of 0.5-3 wt% of total fatty acids, whereas commercially av
ailable infant formulae are almost free of them. Recently, several cli
nical trials, primarily with preterm infants, have reported that the c
ontent of LCPs in the blood and a functional parameter like visual acu
ity correlate with the content of LCPs in the diet. In this clinical t
rial we studied the effect of different diets on the fatty acid patter
n of plasma and erythrocyte lipids of healthy term infants during the
first 3 months of life. Breast-fed infants were compared with formula-
fed babies who received a commercially available formula without LCPs
or a new experimental formula enriched with LCPs that was similar to h
uman milk. The results indicate that the introduction of milk feeding
leads to marked differences in the blood lipid composition during the
first months of life, independent of the feeding regimen. Secondly, th
e supplementation of a formula with LCPs seems to result in a blood li
pid composition similar to infants fed with human milk. This supports
the hypothesis that the newborn term infant has a limited desaturating
capacity and depends on an exogenous supply of LCPs during the first
months of life.