May a standard dietary fiber set off an allergy-like response?

May a standard dietary fiber set off an allergy-like response?

May a standard dietary fiber set off an allergy-like response?Share on Pinterest
Some dietary supplements might have negative effects on sure people. Douglas Sacha/Getty Photographs
  • When intestine microbes break down prebiotic dietary fiber, a number of molecules that may modulate the immune system can type.
  • Nonetheless, scientists nonetheless don’t perceive the inflammatory results that will come up when the physique metabolizes particular dietary fiber varieties.
  • A current examine in mice confirmed that an inulin complement modified the metabolism of sure intestine micro organism, leading to a rise within the serum ranges of bile acids.
  • The researchers noticed that inulin triggered a particular sort of inflammatory response, sometimes noticed in response to allergic reactions and parasitic worms, within the lungs and colon.

A current examine revealed in Nature means that the dietary fiber inulin can alter the composition and metabolism of intestine microbiota, leading to a type-2 inflammatory response, which is usually noticed in response to allergic respiratory circumstances.

The examine calls into query the connection between food plan, immunity, and often helpful prebiotics—on this case, inulin, a dietary fiber generally utilized in anti-inflammatory dietary supplements.

Commenting on the examine’s findings, Dr. Sarkis Mazmanian, a microbiologist on the California Institute of Expertise, mentioned:

“The outcomes are counterintuitive primarily based on earlier literature displaying anti-inflammatory properties of dietary fiber, although how microbiota-derived metabolites form sort 2 immunity is probably going complicated and nonetheless poorly understood.”

Dr. Mazmanian mentioned that the examine affords new insights into how dietary fiber, intestine micro organism, and the immune system work together.

“Extrapolation to people, both by way of organic relevance or doable interventions, stays restricted. Nonetheless, the examine does elevate intriguing new insights that may require replication and additional analysis towards mechanisms of motion,” he informed Medical Information As we speak.

The intestine microbiota performs an vital function in human well being and illness. The intestine microbiota can modify dietary parts and molecules the physique produces, reminiscent of bile acids, to supply an unlimited array of biologically energetic compounds. These metabolites, the intermediate or finish merchandise of bacterial metabolism, can affect the host’s metabolism and immunity.

Weight loss program can affect the composition of the intestine microbiome, which, in flip, can affect the manufacturing of those metabolites.

For example, sure varieties of dietary fiber can act as prebiotics— meals that may affect the expansion and exercise of the intestine microbiota to supply helpful well being results. These prebiotic dietary fibers can’t be digested by human enzymes within the small gut and are damaged down by fermentation by intestine microbes within the massive gut.

The fermentation of undigested dietary fiber by the intestine micro organism produces metabolites reminiscent of short-chain fatty acids, together with acetic acid, butyric acid, and propionic acid. Earlier research have proven that these short-chain fatty acids can have a helpful influence on metabolism and produce anti-inflammatory results.

Nonetheless, along with short-chain fatty acids, the breakdown of dietary fiber by intestine microbiota additionally produces different metabolites, together with branched-chain amino acids, indoles, and bile acids.

There are a number of several types of dietary fiber, together with inulin, cellulose, and lignin, with every dietary fiber sort differentially impacting intestine microbiota composition and the manufacturing of microbiota-derived metabolites.

Though researchers have extensively examined the results of short-chain fatty acids on the metabolic and immune techniques, the results of consuming a food plan wealthy in a particular sort of dietary fiber on the immune system aren’t properly understood.

Within the current examine, the researchers examined the influence of a food plan enriched in inulin, a kind of soluble dietary fiber, on intestine microbiota composition and irritation.

Inulin is a storage carbohydrate in a number of vegetation and consists of repeating models of fructose. For example, inulin is current in bananas, onions, artichokes, garlic, wheat, oats, garlic, and chicory.

Inulin is just not digested within the small gut and is a prebiotic fiber. Animal research counsel that inulin can stimulate the manufacturing of short-chain fatty acids and enhance lipid and glucose metabolism.

Furthermore, there may be proof to counsel that dietary supplementation with inulin can promote weight reduction in people. Consequently, inulin is used as a dietary complement and as a bulking agent in processed meals.

Earlier research had proven that inulin can enhance the degrees of regulatory T cells that may suppress the response of the immune system. Within the current examine, the researchers additional examined the influence of inulin on the immune system in mice.

To look at the influence of inulin on intestine microbiota, the researchers used mice that have been maintained on both an inulin-rich food plan or a calorie-matched management food plan for 2 weeks.

The inulin-rich food plan led to a rise in micro organism belonging to the Bacteroidetes phylum and a decline in these from the Firmicutes phylum.

The inulin-rich food plan additionally engendered adjustments within the ranges of a number of microbiota-derived metabolites within the serum. The biggest change in mice maintained on the inulin-rich food plan was noticed within the serum ranges of bile acids.

Bile acids, the key constituents of bile, are produced by the liver and may facilitate the digestion and absorption of fat within the small gut.

“[The study reveals that] a modified fiber food plan modulates sort 2 immunity by way of results on bile acids, defining a brand new diet-microbiome axis that impacts irritation within the intestine and lungs of mice.”
— Dr. Sarkis Mazmanian

After their synthesis from ldl cholesterol, bile acids are conjugated with the amino acids glycine and taurine within the liver. Upon touring to the gut, bile acids may be remodeled by enzymes produced by intestine micro organism. For example, the bile salt hydrolase enzyme secreted by intestine microbiota deconjugates bile acids from glycine and taurine within the small gut.

Within the current examine, the researchers discovered a rise within the ranges of main varieties of unconjugated bile acids, reminiscent of cholic acid, within the serum.

Earlier research have proven that bile acids can modulate the immune response. Therefore, the researchers examined the results of inulin on the immune response.

Per earlier research, inulin produced a modest enhance in regulatory T-cell ranges. Moreover, mice maintained on an inulin-rich food plan confirmed a rise within the stage of eosinophils, a kind of white blood cells, within the colon and lungs.

Such elevated eosinophil ranges are a attribute of a particular sort of immune response known as type-2 irritation, which is usually noticed in allergic reactions, bronchial asthma, and eczema.

As well as, inulin additionally prompted an upregulation of immune cells and inflammatory proteins concerned in mediating a type-2 inflammatory response.

The researchers then examined the function of intestine microbiota in mediating the inulin-induced type-2 inflammatory response. They discovered that germ-free mice—i.e., mice missing microbiota— maintained on an inulin-rich food plan didn’t present a rise in eosinophil ranges within the colon.

Furthermore, germ-free mice inoculated with a single bacterial pressure and fed an inulin-rich food plan confirmed elevated serum cholic acid ranges and promoted a kind 2 inflammatory response. This inulin-induced type-2 inflammatory response was abolished in germ-free mice inoculated with the identical bacterial pressure missing a useful bile salt hydrolase enzyme.

As well as, oral administration of cholic acid, however not short-chain fatty acids, for two weeks additionally triggered the type-2 inflammatory response just like that noticed with inulin.

These information present that intestine microbiota is critical for mediating the results of inulin on type-2 irritation.

Furthermore, the need for a useful bacterial bile salt hydrolase enzyme to set off the kind 2 inflammatory response suggests a necessary function for microbial metabolism of bile acids in mediating the inulin-induced type-2 irritation.

The inulin-rich food plan additionally prompted adjustments in microbiota composition, a rise in serum bile ranges, and activation of the type-2 inflammatory response within the germ-free mice transplanted with human microbiota.

These results have been just like these noticed in mice with a various microbiota maintained on the inulin-rich food plan. This exhibits that inulin had an analogous influence on each human and mouse microbiota.

The researchers discovered that inulin consumption led to a extra extreme type-2 inflammatory response in mice responding to allergens, reminiscent of home mud mites and the meals additive papain.

For example, publicity to deal with mud mites resulted in a heightened type-2 inflammatory response within the lungs and elevated airway resistance, indicative of a decline in lung perform.

In distinction to those hostile results, the elevated type-2 inflammatory response because of inulin had a protecting impact in opposition to parasitic worms, ensuing of their extra fast removing.

Thus, though inulin might probably exacerbate allergic reactions in inclined people, an inulin-rich food plan might not essentially have a unfavorable influence on wholesome people.

The examine’s writer Dr. Mohammad Arifuzzaman, a postdoctoral researcher at Weill Cornell Medical School, famous, “It could possibly be that this inulin to type-2-inflammation pathway represents an adaptive, helpful response to endemic helminth parasite an infection, although its results in a extra industrialized, helminth-free surroundings are extra complicated and tougher to foretell.”

Molly Rapozo, registered dietician, nutritionist and mind well being coach at Pacific Neuroscience Institute at Windfall Saint John’s Well being Heart in Santa Monica, CA, mentioned dietary fibers may be helpful in a number of methods, and “due to this fact the optimistic results might actually supersede any negatives.”

Nonetheless, she cautioned that extra analysis was wanted, particularly in people.

“The inflammatory impact of inulin on this examine doesn’t essentially outweigh the advantages of dietary fiber total, nonetheless, this is a chance to have a look at our sources of inulin fiber,” she mentioned.

She additionally suggested selecting complete meals sources of prebiotic fibers like inulin, as an alternative of selecting extremely processed meals and dietary supplements.

Getting inulin from meals

“Select extra complete meals sources of inulin reminiscent of Jerusalem artichokes, onions and leeks, garlic, chicory root (in espresso and occasional substitutes), dandelion greens, jicama, asparagus, flaxseed, oats, wheat, and barley.”
— Molly Rapozo, registered dietician



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