Dietary fiber is fermented in the intestines, producing short-chain fatty acids that inhibit inflammation and influence the immune system, which can protect against or at least alleviate allergies.
In a new study, researchers at the Tokyo University of Science examined in vitro and in vivo how short-chain fatty acids influence the function and gene expression of mast cells in mice. The results are published in the “Journal of Immunology”.
Intestinal flora influences health
A healthy diet is beneficial for the intestinal flora and can also have a positive effect on general health and particularly on allergies, the researchers explain.
The fiber consumed, which is mainly found in plant-based foods, is particularly important. When fiber is fermented by the intestinal flora, short-chain fatty acids are formed as secondary metabolites, which, among other things, have anti-inflammatory and immune-modulating effects, the experts explain.
Fatty acids and the immune system
Short-chain fatty acids are known to interact with the immune system, for example by activating mast cells. Mast cells are special white blood cells that are loaded with so-called granules, which contain enzymes and signaling molecules.
When mast cells identify foreign bodies (antigens), these enzymes and signaling molecules are released into the surrounding tissue, leading to a rapid immune response. According to the researchers, mast cells also play a central role in allergic diseases, for example food allergies or hay fever (pollinosis).
There is various evidence that short-chain fatty acids have anti-allergic properties, but the exact mechanisms through which short-chain fatty acids regulate mast cell function are still unclear. In the new study, the team has now tried to close this knowledge gap.
Reduced allergic reactions
The experts found that oral intake of the short-chain fatty acids valerate or butyrate alleviated both passive systemic anaphylaxis and passive cutaneous anaphylaxis (an artificially induced allergic reaction in the laboratory) in mice.
Using mast cell cultures, it was also shown that treating mast cells with various short-chain fatty acids suppressed immunoglobulin E (IgE)-mediated activation, which is a crucial pathway in allergic reactions, the team explains.
The new findings help to understand how the body regulates the immune system with the help of intestinal bacteria, which could particularly benefit people with allergies, the researchers continue.
Possible cause of the increase in allergies
“Mast cell activation is a common cause of various allergic diseases and is not limited to anaphylaxis. “In addition, I think that the increasing frequency of allergy patients is related to a change in diet in these decades,” adds study author Professor Chiharu Nishiyama in a press release.
The new study has revealed part of the complex regulatory mechanisms involving various food-related components, including fiber, short-chain fatty acids, polyunsaturated fatty acids and vitamins, the doctor added.
The results highlight that fiber can be an effective tool for treating allergies and how important diet is for overall health and for protecting and alleviating allergies, the research team concluded. (as)