In functional medicine, we search high and low for studies that either explain mechanisms of therapies we already use successively or for new ways to use old therapies. Folkerts et al in Frontiers of Immunology accomplished both goals in a 2018 article I just found. Like all discoveries, it is built on the work of countless others to lay a foundation. From the growing understanding of mast cell function to the growing epidemic of allergic diseases, there was added a recognition of fiber and its breakdown product, butyrate, in modulating allergic diseases. In this paper, they walked through a series of studies to highlight the various mechanisms others had discovered linking fiber and mast cells.
Mast cells are immune system sentries residing in tissue and organs where our body contacts the outside world, like skin, GI tract, and other mucosal surfaces. When they sense something wrong, they send out signals for help which bring other inflammatory cells and chemicals. Their activation is involved in allergic diseases of all types. If we can find a way to modulate their function, we may be able to control allergic disease or maybe prevent it.
Butyrate belongs to a group of gut bacteria metabolites called short chain fatty acids (SCFA). While humans do not possess enzymes capable of digesting fiber in our diets, the bacteria living in our colon break the fiber down into a variety of chemicals including SCFA like butyrate, acetate, and propionate. These short chain fatty acids serve a number of niche functions in human physiology. For example butyrate is used as an energy source for intestinal lining cells.
The low fiber intake of the Western diet has been linked to increasing allergic diseases in various epidemiologic studies. As fiber intake increases, the Bacteroidetes to Firmicutes ration improves such that the higher counts of Bacteriodetes produce higher amounts of SCFA’s. SCFA’s were already known to activate cell membrane receptors GPR41, GPR43, GPR103, and peroxisome proliferator-activate receptors (PPAR) (see references 19-21 in the article). They can downregulate histone deacetylase enzyme which affects gene expression.
The paper authors worked through various clinical settings where fiber or butyrate show potential for clinical benefit. They include food allergies, inflammatory bowel disease (mast cells play a role in its development), airway inflammation, and atopic dermatitis.
As often as is possible in functional medicine, we try to use therapies which have multiple benefits. If I can use a single herb that meets three needs for my patient, it is a win-win for both of us. With butyrate, I occasionally recommend it for gut healing, but armed with this article I may apply it to allergic diseases and even inflammatory bowel disease. Likewise, as I encourage almost all patients to eat more fiber, I can give them one more reason that it is good for them. Just another couple of ways to help our patients live healthier more abundant lives.
Folkerts, Jelle et al. “Effect of Dietary Fiber and Metabolites on Mast Cell Activation and Mast Cell-Associated Diseases.” Frontiers in immunology vol. 9 1067. 29 May. 2018, doi:10.3389/fimmu.2018.01067