INDIVIDUAL FISH-OIL N-3 POLYUNSATURATED FATTY-ACID DEPOSITION AND MOBILIZATION RATES FOR ADIPOSE-TISSUE OF RATS IN A NUTRITIONAL STEADY-STATE

The storage in and mobilization from rat adipose tissue of 20:5n-3, 22 :6n-3, 22:5n-3, and 18:4n-3 fatty acids were investigated. After fish- oil feeding, substantial amounts of these fatty acids were stored in f at depots. However, the in vivo relative incorporation (% in triacylgl ycerols/% in diet) increased significantly in this order: 20:5n-3 (0.2 5) < 18:4n-3 (0.37) < 22:6n-3 (0.49) < 22:5n-3 (0.78). The in vitro re lative mobilization (% in free fatty acids/% in triacylglycerols) decr eased significantly in this order: 20:5n-3 (2.88) > 18:4n-3 (1.51) > 2 2:6n-3 (1.08) > 22:5n-3 (0.91). Similar results were obtained from rat s maintained on a low-fat control diet. Dietary essential n-3 polyunsa turated fatty acids are therefore selectively mobilized from fat store s, which could explain their selective storage. The preferential mobil ization of eicosapentaenoic acid could contribute to its maintenance i n the circulation after fish-oil feeding, but it probably limits its p ostintake long-term storage.