A press release on the topic notes that previous studies have shown that obesity is a risk factor for the development or worsening of psoriasis; the diet, characterized by high intake of saturated fats and sucrose and low intake of fiber, has been linked to the increased prevalence of obesity. And it seems that the Western diet is the cause of both, rather than one causing the other: Sam T. Hwang, Professor and Chair of dermatology at UC Davis and senior author of the study, said in the release: “On our study, we found that short-term exposure to Western diet is able to induce psoriasis before significant body weight gain.”
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The study fed mice a diet that mimicked the Western diet, and within four weeks, the mice had significantly increased ear swelling and visible dermatitis compared to mice fed a controlled diet and to mice on a high-fat diet.The study identified bile acids as key signaling molecules in the regulation of skin immunity. Bile acids are produced in the liver from cholesterol and metabolized in the intestine by the gut microbiota. They play a role in lipid absorption and in cholesterol balance in the blood. Cholestyramine, a drug used to lower cholesterol levels by binding bile acids, was found in the study to reduce the risk of skin inflammation, suggesting that bile acids mediate the development of psoriasis.
The release notes that further studies are needed to understand the mechanism behind diet-induced skin inflammation and the interaction between metabolism, microbes, and immunity.