The investigators examined the effect of different levels of docosahexaenoic aicd (a long chain polyunsaturated fatty acid) intake on the fatty acid composition of plasma and erythrocyte phospholipids and on the maturity of visually evoked potentials in preterm infants. As a secondary outcome the conversion of linoleic acid and alpha linolenic acid into their corresponding long chain polyunsaturated fatty acids was studied.

Preterm infants were randomized in a double-blind fashion to one of three formulas containing different amounts of docosahexaenoic acid during the first two weeks of postnatal life. A control group received human milk. Blood samples were collected at study entry and 14 and 28 days thereafter. Uniformly 13C-labeled linoleic acid and alpha linolenic acid were applied orally before blood sampling at day 28. At postconceptional ages 48 weeks and 56 weeks visually evoked potentials were recorded.

Inclusion Criteria:

• preterm birth
• birth weight between 1000 and 2200 g
• more than 80 % of energy intake from infant formula or human milk at enrollment

Exclusion Criteria:

• apparent genetic, gastrointestinal or metabolic disorders
• artificial ventilation or oxygen supply > 30% at the time of enrollment
• administration of parenteral fat emulsion (> 1 g/kg/day for more than seven days) before or after study entry