Background. There are few studies on Arachidonic (AA) and Docosahexaenoic(DHA) acids intestinal absorption. It is not well known if the plasma pattern is modified by the fatty acid formula content.

Subjects. 26 AGA preterm babies were divided into three groups according to the formula received. Only formula PB contains AA 0.3% wt/wt and DHA 0.16% wt/wt. Seven day metabolic balances were performed. C8-C26 fatty acids-were quantitated though mass spectrometry, in formula, faeces, plasma and in erythrocyte membranes.

Results: Absorption of total fat was similar in the three groups (94-88%). In group PB net absorption for AA was 14.1 mg/Kg/d (75.2%) and for DHA 7.6 mg/Kg/d (71.0%). Plasma values (% wt/wt) were respectively in the three groups for AA 3.9±1.7; 3.0±1.2; 3.9±2.3 and for DHA 1.0±5;.9±.4; 1.0±.3.

Conclusion: Fatty acid pattern of RBC and plasma PL tends to remain unchanged despite the variety of fatty acid supplied.