The effects of a fish-oil-enriched diet on pulmonary mechanics during anaphylaxis

Effect of arachidonic and eicosapentaenoic acids on acute lung injury induced by hypochlorous acid

BACKGROUND

Hypochlorous acid (HOCl) is the main oxidant of activated polymorphonuclear neutrophil granulocytes (PMN) and generated by myeloperoxidase during respiratory burst. This study investigates the effects of HOCl on pulmonary artery pressure (PAP) and vascular permeability and characterises the influence of arachidonic acid (AA) and eicosapentaenoic acid (EPA) on the observed effects.

METHODS

HOCl (500, 1,000, 2,000 nmol/min) was continuously infused into the perfusate (Krebs-Henseleit buffer solution, KHB). AA or EPA in subthreshold doses (both 2 nmol/min) or buffer were simultaneously infused using a separate port. PAP, pulmonary venous pressure (PVP), ventilation pressure, and lung weight gain were continuously recorded. The capillary filtration coefficient (Kf,c) was calculated before and 30, 60, and 90 minutes after starting the HOCl infusion.

RESULTS

HOCl application resulted in a dose dependent increase in PAP and Kf,c. The onset of these changes was inversely related to the HOCl dose used. The combined infusion of AA with HOCl resulted in a significant additional rise in pressure and oedema formation which forced premature termination of all experiments. The combination of EPA with HOCl did not result in an enhancement of the HOCl induced rise in pressure and oedema formation.

CONCLUSIONS

Changes in the pulmonary microvasculature caused by HOCl are differently influenced by omega-6 and omega-3 polyunsaturated free fatty acids, suggesting a link between neutrophil derived oxidative stress and pulmonary eicosanoid metabolism.

Effects of a fish oil enriched diet on aspirin intolerant asthmatic patients: a pilot study

The effect of a fish oil enriched diet containing about 3 g of eicosapentaenoic acid was studied in 10 patients with aspirin intolerant asthma. Subjects were studied during six weeks on a control diet followed by six weeks on the fish oil diet in a single blind study design. They were asked to record their peak expiratory flow (PEF) twice daily, bronchodilator and steroid doses, and subjective ratings of pulmonary symptoms on diary cards. There were no significant changes in symptom scores over the six weeks of either the control diet or the fish oil diet. PEF values, however, were significantly lower during the fifth and sixth week of the fish oil diet than during the control diet (308 v 262 l/min week 5 and 306 v 256 l/min week 6). Bronchodilator usage was also greater during the fifth and sixth week of the fish oil diet than during the control period (12.0 v 7.4 and 13.0 v 7.4 puffs a day in weeks 5 and 6). This pilot study suggests that fish diets may have a deleterious effect on patients with aspirin intolerant asthma.

Biological effects of fish oils in relation to chronic diseases

The low incidence of cardiovascular disease in Greenland Eskimos appears to be due to their high intake of seal, whale and fish. The lipids of these marine animals lower serum triglyceride and cholesterol levels and help to prevent blood clotting. The latter effect has been related to a change in the balance of prostacyclin and thromboxane as a result of replacing n-6 polyunsaturated fatty acids in the body by n-3 polyunsaturated fatty acids present in marine lipids. Dietary fish oils have also been shown to inhibit development of mammary, pancreatic, intestinal and prostatic tumors in experimental animals. This effect may likewise be due to changes in the production of prostaglandins or related compounds. The involvement of prostaglandins and leukotrienes in immune responses has led to studies on the effects of fish oil on various chronic diseases associated with abnormalities of the immune system. Some of these diseases, such as multiple sclerosis and psoriasis, are also relatively uncommon in Eskimos. Preliminary results of these studies are encouraging, but more work is required to assess the usefulness of dietary fish oils in treatment of these diseases. In addition to their apparent therapeutic value, n-3 fatty acids are considered essential dietary components since they cannot be synthesized in the body and appear necessary for normal vision and probably other body functions.