Switching from a western diet to a balanced diet may reduce inflammation of the skin and joints

The secret to healthier skin and joints may lie in the intestinal microorganisms. A study by researchers at UC Davis Health found that a diet high in sugar and fat causes an imbalance in the microbial culture of the gut and may contribute to inflammatory skin diseases such as psoriasis.

The study, published in the Journal of Investigative Dermatology, suggests that switching to a more balanced diet diet restores the health of the intestine and removes skin inflammation.

“Previous studies have shown that the Western diet, characterized by its high sugar and fat content, can lead to significant skin inflammation and psoriasis flare-ups, “said Sam T. Hwang, professor and president of dermatology at UC Davis Health and lead author of the study.” Despite potent anti-inflammatory drugs for the skin, our study indicates that simple changes in diet can also have effects on psoriasis. “

What is psoriasis?

Psoriasis is a stubborn skin condition related to the body’s immune system. When immune cells mistakenly attack healthy skin cells, they cause inflammation of the skin and the formation of red, itchy scales and patches.

Up to 30% of psoriasis patients also suffer from psoriatic arthritis with symptoms such as morning stiffness and fatigue, swollen fingers and toes, joint pain and nail changes.

Diet affects the microbial balance in the intestines and inflammation of the skin

Diet is one of the main modifiable factors regulating the intestinal microbiota, the community of microorganisms living in the intestines. Eating a western diet can cause a rapid change in the gut’s microbial community and its functions. This disturbance of the microbial balance, known as dysbiosis, contributes to intestinal inflammation.

Since gut bacteria can play a key role in the formation of inflammation, the researchers wanted to test whether gut dysbiosis affects inflammation of the skin and joints. They used a mouse model to study the effect of diet on psoriasis and psoriatic arthritis. They injected mice with interleukin-23 (IL-23) minicircle DNA to induce a response mimicking skin and joint disease like psoriasis.

IL-23 is a protein generated by the immune cells responsible for many autoimmune inflammatory reactions, including psoriasis and inflammatory bowel disease (IBD).

Hwang and colleagues found that a short-term Western diet appears to be sufficient to cause microbial imbalance and increase susceptibility to IL-23-mediated psoriasis-like skin inflammation.

“There is a clear link between inflammation of the skin and changes in the gut microbiome due to food intake“Hwang said.” The bacterial balance in the gut was disrupted soon after starting a Western diet and worsening the inflammation of the psoriatic skin and joints.

A critical finding of their work was to identify the gut microbiota as a pathogenic link between diet and manifestations of psoriatic inflammation. The study also found that the antibiotics block the effects of the Western diet, thereby reducing inflammation of the skin and joints.

Is the damage caused by poor nutrition reversible?

The researchers wanted to test whether the switch to a balanced diet could restore the gut microbiota, despite the presence of inflammatory proteins IL-23. They fed mice a Western diet for six weeks before giving them an IL-23 inducing agent to trigger the hallmarks of psoriasis and psoriatic arthritis. Then they randomly divided the mice into two groups: a group that continued the Western diet for another four weeks and a group that switched to a balanced diet for the same amount of time.

Their study showed that a diet high in sugar and fat for 10 weeks predisposed mice to inflammation of the skin and joints. The mice that have passed to a Balanced diet had less peeling skin and reduced ear thickness than mice on a Western diet. Skin improvement inflammation for mice removed from the Western diet indicates a short-term impact of the Western diet on inflammation of the skin.

This suggests that diet changes may partially reverse the pro-inflammatory effects and altered gut microbiota caused by the Western diet.

“It was quite surprising that a simple modification of the diet containing less sugar and fat could have significant effects on psoriasis,” said Zhenrui Shi, visiting associate researcher in the department of dermatology at UC Davis and lead author of the study. “These results reveal that patients with psoriatic skin and joint conditions should consider switching to a healthier diet.”

“This work reflects a fruitful collaboration between researchers, in particular with Prof. Satya Dandekar and his team from the Department of Medical Microbiology and Immunology and Prof. Yu-Jui Yvonne Wan from the Department of Medical Pathology and Laboratory Medicine,” Hwang said.