Endotoxin challenge after menhaden oil diet: effects on survival of guinea pigs.

Improvement in survival to endotoxin has been seen after pretreatment with cyclooxygenase inhibitors. Because eicosapentaenoic acid (EPA), found in menhaden oil, competitively inhibits cyclooxygenase, we fed two groups of guinea pigs diets, in which the fat source was either menhaden or safflower oil, for 6 wk. A third group was allowed the safflower oil diet ad libitum. Menhaden oil-fed animals showed enhanced survival compared with safflower oil control animals 20 h after endotoxin (87 vs 63%, p less than 0.05). Ad libitum-fed safflower oil animals survived least well, with 47% alive at 20 h (p less than 0.005 vs menhaden oil group). We conclude that feeding animals a diet whose predominant lipid source is fish oil significantly improves survival after endotoxin. Dietary fat should be viewed not only as a caloric source but as a pharmacologically active substance that can have profound effects on the host's response to toxic insults.