Dietary supplementation with very-long-chain n-3 fatty acids was no better than corn-oil supplementation in treating psoriasis. Clinical improvement was not correlated with an increase in the concentration of n-3 fatty acids in serum phospholipids among the patients in the fish-oil group, whereas there was a significant correlation between clinical improvement and an increase in eicosapentaenoic acid and total n-3 fatty acids in the corn-oil group.

The effect of marine n-3 polyunsaturated fatty acids on proliferation of human T-cells in vitro was compared to other polyunsaturated, monounsaturated and saturated fatty acids. Monoenes and saturated fatty acids had little effect on T-cell proliferation. Eicosapentaenoic acid and docosahexaenoic acid exerted a strong dose-dependent inhibitory effect on proliferation of mitogen- or antigen-stimulated T-cells, similar to that observed for arachidonic acid. Sixty microM of albumin-bound eicosapentaenoic acid or arachidonic acid promoted 25-40% inhibition of proliferation of T-cells stimulated with mitogen, whereas the same concentration of albumin-bound docosahexaenoic acid promoted 60% inhibition. When epidermal cells (Langerhans cells) were used as antigen-presenting cells, 100 microM of albumin-bound eicosapentaenoic acid or arachidonic acid caused 40% inhibition on T-cell proliferation. Low density lipoprotein (LDL), isolated after four months of dietary intake of fish oil or corn oil, inhibited mitogen-stimulated T-cell proliferation in a dose-dependent manner. Fish oil- and corn oil-enriched LDL showed similar ability to inhibit T-cell proliferation. Epidermal cells preincubated with docosahexaenoic acid, and extensively washed before adding purified T-cells and antigen, resulted in a strong inhibition of T-cell proliferation, whereas preincubation of purified T-cells with docosahexaenoic acid did not cause any inhibitory effect. Cyclooxygenase and lipoxygenase inhibitors (indomethacin, acetylsalicylic acid, nordihydroguaertic acid) did not affect the antiproliferative effect of eicosapentaenoic acid and arachidonic acid, neither did the antioxidants butylated hydroxytoluene or alpha-tocopherol. Eicosanoids, (PGE2, PGE3, LTB4, LTB5 and lipoxin A or lipoxin B) added directly to mitogen-stimulated peripheral blood mononuclear cells (PBMC) did not influence T-cell proliferation significantly. Decreased viability was observed when mitogen-stimulated lymphocytes were cultured with essential polyunsaturated fatty acids, whereas the viability of unstimulated lymphocytes was hardly influenced by the same fatty acids. We conclude that; (a) pharmacological albumin-bound concentrations of the highly unsaturated fatty acids eicosapentaenoic acid and docosahexaenoic acid promote a strong antiproliferative effect on mitogen- and antigen-stimulated human T-cells: (b) docosahexaenoic acid can suppress accessory cell function and consequently suppress T-cell activation; (c) physiologic concentration of LDL particles rich in n-3 and n-6 fatty acids, both promote a dose-dependent antiproliferative effect on mitogen-stimulated PBMC; (d) the inhibition is independent of eicosanoid metabolites; and (e) lipid peroxidation seems unlikely to be responsible for the antiproliferative effect.

Our data show that clinical improvement of psoriasis following sun exposure is preceded by a rapid reduction in local and systemic inflammatory markers, strongly suggesting that immune modulation mediated the observed clinical effect. We cannot completely rule out that other mechanisms, such as stress reduction, may contribute, but it is extensively documented that UV irradiation is a potent inducer of immunosuppression and we therefore conclude that the observed effect was primarily due to sun exposure.

The purpose of this study was to investigate whether fish oil and/or corn oil had a beneficial effect on the clinical state of atopic dermatitis, and to evaluate the dietary intake of nutrients in this group of patients. In a double-blind, multicentre study lasting 4 months, during wintertime, 145 patients with moderate to severe atopic dermatitis were randomly assigned to receive either 6 g/day of concentrated n-3 fatty acids, or an isoenergetic amount of corn oil. As local treatment, only an emollient cream or hydrocortisone cream was allowed. The fatty acid pattern in serum phospholipids, and the dietary intake of nutrients were monitored in a subgroup of patients, and the results were compared with a group of patients with psoriasis. The overall clinical score, as evaluated by the physicians, improved during the trial by 30% in the fish oil (P < 0.001) and 24% in the corn oil group (P < 0.001). This was also consistent with the results from a selected skin area, and it was further confirmed by the total subjective clinical score reported by the patients. There were no significant differences in the clinical scores between the two groups at baseline, and at the end of the study. In the fish oil group, the amount of n-3 fatty acids in serum phospholipids was significantly increased at the end of the trial, compared with pretreatment values (P < 0.001), whereas the level of n-6 fatty acids was decreased (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Background Climate therapy (heliotherapy) of psoriasis is an effective and natural treatment. Ultraviolet radiation (UVB)