Benefits from oily fish

Fish Oil Supplementation Inhibits Platelet Aggregation and ATP Release Induced by Platelet-activating Factor and Other Agonists

The anti-inflammatory effects of fish oil may partly be due to the inhibition of platelet activation induced by platelet-activating factor (PAF) and other agonists. To investigate this hypothesis, the diets of 12 healthy volunteers were supplemented with 12 fish oil capsules or 12 olive oil capsules daily for 4 weeks in a double blind crossover study. Aggregation induced by PAF (18 and 12.5 nM) and collagen (20 μg/ml)tended to be reduced after fish oil but the effect was statistically significant only in subjects receiving fish oil in the 6rst 4 weeks of the study (P 0.05, n=6). The effect of fish oil supplementation on platelet ATP release was more marked with significant inhibition of ATP release induced by PAF (1200 and 36 nM, P 0.01, n = 12), collagen (20 μg/ml, P 0.005, n = 12) and ADP (15,10 and 5 μM, P 0.05, n = 12). Olive oil supplementation appeared to inhibit ATP release induced by collagen (45 and 30 μg/ml, P> 0.025, n = 12), while aggregation and ATP release induced by arachidonic acid and adrenaline were unaffected by the supplements. Plasma fibrinogen was significantly reduced after olive oil (P 0.01, n = 12) while prothrombin time was reduced after fish oil (P 0.001, n = 12) and olive oil (P 0.0025). Reduced platelet aggregation and more importantly, inhibition of platelet release induced by PAF and other agonists may contribute to the anti-inflammatory effects of fish oil supplementation in a number of disease states but olive oil may also independently affect platelet function and influence the effect offish oil.

Asthma, oxidant stress, and diet

It has been suggested that the increased prevalence of atopy and asthma observed in many developed countries over the past 30 y is in part the result of a decrease in the incidence and severity of early childhood infections. The immunologic consequence of this phenomenon has been the expansion of T-lymphocyte populations away from the T-helper 1 (Th1) subset and in the direction of the Th2 subset. This leads to the creation of a cytokine-mediated propensity for the development of an intense inflammatory response in the airways, resulting in oxidative stress, airway tissue injury, and the development of atopy and asthmatic symptomatology. Over this same period, there has been a decreased intake of dietary substances that contribute to antioxidant defense, and this appears to have contributed to the rise of atopy and asthma. Studies evaluating the efficacy of these antioxidant substances in the prevention of asthma and as adjuvants in the treatment of asthma are reviewed, and suggestions are made for the direction of future studies.

Highly purified omega-3-polyunsaturated fatty acids for topical treatment of psoriasis. Results of a double-blind, placebo-controlled multicentre study

We report the results of a multicentre, double-blind, placebo-controlled study of topical therapy with omega-3-polyunsaturated fatty acids (omega-3-PUFA) in 52 patients suffering from moderate plaque-type psoriasis. In each patient, two similar stable psoriatic plaques served as indicator lesions for the study. One indicator lesion was randomly assigned to treatment with topical preparations of highly purified omega-3-PUFA in one of two concentrations (1 or 10%), and the other was treated with placebo. Efficacy assessment was based on changes in local psoriasis severity index, area involved, erythema, desquamation, induration and pruritus. After 8 weeks of treatment, all indicator lesions had improved significantly, compared with baseline. However, no statistically or clinically relevant differences between the omega-3-PUFA-treated and the placebo-treated lesions were found. Therapy was well tolerated and, apart from one patient who developed perilesional eczema, no clinically relevant adverse events occurred. In conclusion, topical omega-3-PUFA were not effective in a randomized, placebo-controlled, double-blind setting. Results of non-blind trials should be (re-)considered with caution.

The effect of eicosapentaenoic acid consumption on human neutrophil chemiluminescence

The effect of eicosapentaenoic acid (EPA) on the inflammatory potential of neutrophils was investigated by supplementing the diets of 12 subjects with 2.16 g of EPA or 12 g of olive oil per day for 4 weeks in a double blind crossover study. Neutrophil function as assessed by luminol enhanced chemiluminescence responses to platelet-activating factor (PAF) and formyl-methionyl-leucyl-phenylalanine (FMLP) was significantly reduced after EPA but not after olive oil consumption in the subjects who consumed EPA first. In contrast, EPA had no significant effect on neutrophil chemiluminescence in the subjects who consumed olive oil first. Dietary supplementation with EPA inhibits neutrophil responses to inflammatory mediators such as PAF while other fatty acids appear to modify the effects of EPA.

n-3 fatty acids and leukocyte chemotaxis. Effects in hyperlipidemia and dose-response studies in healthy men

Dietary supplementation with n-3 polyunsaturated fatty acids (n-3 PUFAs) has been shown to inhibit neutrophil and monocyte chemotaxis in healthy subjects and, with respect to neutrophils, also in various patient groups. We studied the effect of dietary supplementation with n-3 PUFAs on monocyte and neutrophil chemotaxis in patients with hyperlipidemia. Chemotaxis was investigated with the under-agarose assay, using autologous serum and N-formyl-methionyl-leucyl-phenylalanine as chemoattractants. The patients were examined before and after 6 weeks of supplementation with 6 g n-3 PUFAs daily. Monocyte chemotaxis was reduced after n-3 PUFA supplementation in type IIa patients but was unaffected in patients with type IV hyperlipidemia. Furthermore, monocyte chemotaxis was increased in untreated type IIa patients compared with normocholesterolemic controls. We also studied the dose-response effects of n-3 PUFAs on monocyte and neutrophil chemotaxis in healthy men given 1.3, 4, and 9 g n-3 PUFAs daily for 6-week periods. Monocyte and neutrophil chemotaxis was reduced after n-3 PUFA supplements in a dose-dependent fashion, with the majority of the effect observed after the low dose. These results lend support to the notion of an antiatherosclerotic effect of n-3 PUFAs and may provide an explanation for the hitherto-unexplained effect of low doses of n-3 PUFAs in coronary heart disease.

Red blood cell and adipose tissue fatty acids in mild inactive multiple sclerosis

The fatty acid profiles of phosphatidyl ethanolamine (PE) and phosphatidyl choline (PC) of the red blood cells of 30 patients with mild inactive multiple sclerosis (MS) and 30 healthy controls were studied by gas chromatography. The groups were well matched for factors likely to influence tissue lipid levels, including diet. The MS patients showed a significant reduction in PE eicosapentaenoic acid (p = 0.009) especially in women, and an increase in both PE dihomo-gamma-linolenic acid (p = 0.004) and PC stearic acid (p = 0.04). No reduction in linoleic acid was observed in either the PC or PE fractions of the MS subjects. A similar study of the fatty acid profile in adipose tissue in 26 MS and 35 healthy controls found no detectable eicosapentaenoic acid in either group. However, whereas docosahexaenoic acid was not detectable in any MS patient, 40% of the controls had measurable levels varying from to 0.1 to 0.3% of total estimated fatty acid (p = 0.0003). No reduction in linoleic acid in MS subjects was observed. Supplementation with oral fish body oil demonstrated that n-3 fatty acids were incorporated into red blood cells over 5 weeks and this occurred equally in MS and controls. The effects of oral supplementation on adipose tissue were studied after 1 and 2 years. Whereas many fatty acids such as linoleic acid were raised at 1 year, but did not rise subsequently, eicosapentaenoic acid and docosahexaenoic acid continued to rise through the 2-year period.(ABSTRACT TRUNCATED AT 250 WORDS)