An unintended benefit of having a high-fiber diet is protection against skin allergens, finds a new mouse study from Monash University. Researchers show that the gut’s fermentation of fiber strengthened the skin barrier, preventing environmental allergens from entering the body.
The research could pave a new direction for new allergy treatments.
The gut microbiome is involved in regulating the immune system, but its role in how the immune system reacts to skin irritants remains less understood. While some people have touted the importance of diet on skin health, there is no strong evidence for this, according to the team.
“Previous work from our group, and others, has focused on the local health benefits of [short chain fatty acids] in the gut as well as at distal sites such as the lung and cardiovascular system,” says study co-author Ben Marshland, an immunology professor, in a statement. “We wondered if this might also extend to the skin, which is an area that has not really been investigated.”
Researchers fed mice a fermentable high-fiber diet or purified short-chain fatty acids. Certain bacterial species and short-chain fatty acids, especially butyrate, are involved in microbial fermentation. Butyrate was labeled with isotopes to track it in the body. Within minutes, butyrate reached the skin where it provided a metabolic boost for keratinocytes. The increased metabolism allowed keratinocytes to mature and produce a healthy skin barrier.
“The upshot of this was that the skin barrier was fortified against allergens – we were using house dust mite allergens – that would normally penetrate the skin barrier, activate the immune system and start an allergic reaction in these models,” says Marshland. “It turns out the immune system was secondary to this skin barrier function.”
A reinforced skin barrier could make it harder for environmental exposures that cause allergies or skin diseases to penetrate the skin and enter the body. Marshland says one treatment avenue is applying a topical cream filled with short-chain fatty acids directly on the skin, removing the gut as the middle man.
“The fact that short-chain fatty acids can be given topically and are well-tolerated opens up possibilities for the development of preventative strategies or disease-modifying interventions – that represents the most significant translational potential of our research,” explains Marshland.
Another possibility is preventing further allergies, such as in children who first have skin allergies and later develop food allergies or asthma.
The study is published in the journal Mucosal Immunology.