Butyrate, a short-chain fatty acid produced in the gut, reduces skin allergies.

The skin is an important biological barrier that plays critical roles in the body’s innate immune response. Skin allergies, which typically appear early in life and can impair barrier function, have become more common in recent decades. Findings from a recent study suggest that butyrate, a short-chain fatty acid produced in the gut, reduces atopic dermatitis, a type of skin allergy.

Short-chain fatty acids are fatty acids that contain fewer than six carbons in their chemical structure. They are produced by the gut microbiota during the fermentation of dietary fiber and are crucial to gut health. Short-chain fatty acids may play roles in the prevention and treatment of metabolic syndrome, inflammatory bowel disorders, and certain types of cancer. Some evidence suggests they can cross the blood-brain barrier to affect brain function. The principal short-chain fatty acids produced in the human gut are acetate, propionate, and butyrate.

The investigators first exposed two groups of mice to an allergen that induces a skin condition similar to atopic dermatitis. They fed both groups a low-fiber diet, but they supplemented one group with inulin, a type of fiber that undergoes microbial fermentation in the gut to produce butyrate. They supplemented the other group with cellulose, which does not readily ferment. They found that compared to the cellulose-supplemented mice, the mice that ate the inulin-supplemented diet had less severe skin disease, better barrier function, and a milder immune response, which they attributed to butyrate.

Next, they tracked the movement of butyrate in the animals' bodies and determined that it traveled quickly from the gut to the skin (about 45 minutes), where it directly influenced the mitochondrial metabolism of keratinocytes, the dominant cell type in the epidermal layer of the skin. Finally, they analyzed gene expression in skin collected from both groups of mice and observed a twofold increase in gene expression related to immunity and barrier function in the butyrate-exposed mice.

These findings suggest that butyrate influences skin health and reduces skin allergies. Learn more about the beneficial health effects of butyrate in our overview article.

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