Not all fats are equal in how they affect our skin, according to a new study in the Journal of Investigative Dermatology, published by Elsevier. The investigators found that different ketogenic diets impacted skin inflammation differently in psoriasiform-like skin inflammation in mice. Ketogenic diets heavy in medium-chain triglycerides (MCTs) such as coconut, especially in combination with omega-3 fatty acids from fish oil and plant sources like nuts and seeds, exacerbated psoriasis.

'This study leads to a broader understanding of possible effects of ketogenic diets with a very high fat content on skin inflammation and underlines the importance of the composition of fatty acids in the diet," explained co-lead investigator, Barbara Kofler, PhD, Research Program for Receptor Biochemistry and Tumor Metabolism, Department of Pediatrics, Paracelsus Medical University, Salzburg, Austria. "We found that a well-balanced ketogenic diet, limited primarily to long-chain triglycerides (LCTs) like olive oil, soybean oil, fish, nuts, avocado, and meats, does not exacerbate skin inflammation. However, ketogenic diets containing high amounts of MCTs especially in combination with omega-3 fatty acids, should be used with caution since they may aggravate preexisting skin inflammatory conditions."

Ketogenic diets are increasingly popular because of their promise to treat a number of diseases and promote weight loss. They are currently being evaluated as a potential therapy in a variety of diseases and have been suggested to act as an anti-inflammatory in certain conditions. Dietary products containing coconut oil (high in MCTs) or fish oil (high in omega-3 fatty acids), consumed as part of a ketogenic diet, are marketed and used by the general population because of their reported health promoting effects.

Previous studies have indicated that high-fat diets with a substantial amount of carbohydrates promote the progression of psoriasiform-like skin inflammation and development of spontaneous dermatitis in mice. The investigators therefore hypothesized that high-fat ketogenic diets would dampen psoriasiform-like skin inflammation progression and that partial supplementation of LCT with MCT and/or omega-3 fatty acids would further enhance these effects. Although the study did not confirm that hypothesis, it showed that an LCT-based ketogenic diet does not worsen skin inflammation.

Co-lead investigator Roland Lang, PhD, Department of Dermatology, Paracelsus Medical University, Salzburg, Austria, elaborated on the study's results, "Ketogenic diets supplemented with MCTs not only induce the expression of pro-inflammatory cytokines, but also lead to an accumulation of neutrophils in the skin resulting in a worse clinical appearance of the skin of the mice. Neutrophils are of particular interest since they are known to express a receptor for MCTs and therefore a ketogenic diet containing MCTs may have an impact on other neutrophil-mediated diseases not limited to the skin."

Mice used in the study were fed an extremely high-fat (77 percent) ketogenic diet, which is uncommon except for patients following a strict regime for medical conditions like drug-resistant epilepsy. "I think most people following a ketogenic diet don't need to worry about unwanted skin inflammation side effects. However, patients with psoriasis should not consider a ketogenic diet an adjuvant therapeutic option, noted Dr. Kofler."