A high-fiber diet rich in vitamin A may alter gut bacteria in a way that could prevent or reverse food allergies. This is the finding of a new study published in the journal Cell Reports.

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Researchers say a high-fiber diet enriched with vitamin A shows promise for reducing the risk of food allergy.

It is estimated that around 15 million people in the United States have food allergies, and this number is increasing.

According to the Centers for Disease Control and Prevention (CDC), between 1997-2007, the number of children and adolescents in the U.S. with food allergies rose by around 18 percent, though the reasons for this are unclear.

Eight food types account for around 90 percent of all food allergies. These are peanuts, tree nuts, egg, milk, wheat, soy, fish, and shellfish.

Allergic reactions to food vary from person to person, but they may include tingling or itching in the mouth, hives, nausea or vomiting, stomach pain, and diarrhea.

In more severe cases, a person with a food allergy may experience swelling of the lips, tongue, and/or throat, shortness of breath, trouble swallowing, chest pain, and a sudden drop in blood pressure.

Occurrence of severe symptoms – alone or alongside milder ones – could be indicators of anaphylaxis, a potentially life-threatening reaction that requires immediate medical attention.

Of course, the best way to avoid an allergic reaction to food is to avoid consuming the food that triggers it, though this can be easier said than done.

Now, a new study suggests there may be a simple way to prevent or reverse food allergies: a high-fiber diet, enriched with vitamin A.

Co-senior author Laurence Macia, of Monash University in Australia, and colleagues came to their conclusion after studying mice that were artificially bred to be allergic to peanuts.

The researchers fed some of the mice a high-fiber diet rich in vitamin A – found in many fruits and vegetables – while others were fed a diet with average fiber, sugar, and calorie content (the controls).

Fast facts about food allergy
  • In the U.S., someone is sent to the emergency room every 3 minutes due to a food allergy reaction
  • Childhood food allergies cost the U.S. around $25 billion every year
  • 1 in 13 children in the U.S. have food allergies.

Learn more about food allergy

They found that the mice fed the high-fiber diet had less severe allergic reactions to peanuts than mice fed the control diet.

On closer analysis, the researchers found that the high-fiber diet altered the gut bacteria of mice, which protected them against allergic reactions to peanuts.

Next, the researchers took some altered gut bacteria from mice fed the high-fiber diet and transferred it to the guts of mice with a peanut allergy that were “germ-free” – that is, they had no gut microbes.

Even though these germ-free mice were not fed a high-fiber diet, the team found that the addition of the altered gut bacteria protected them against allergic reactions to peanuts.

The researchers explain that gut bacteria break down dietary fiber into short-chain fatty acids.

In their study, the team found that increased levels of these fatty acids work with the body’s immune system, preventing dendritic cells – which regulate food allergies – from triggering an allergic response. Vitamin A is also important for dendritic cell regulation.

Their findings were supported when the team gave the allergic mice water enriched with short-chain fatty acids for 3 weeks, before exposing them to peanuts. Their allergic response was reduced.

Overall, the researchers say their findings indicate that a diet low in fiber could be driving food allergies, and that adopting a high-fiber diet – enriched with vitamin A – could be way to lower food allergy risk.

It’s likely that compared to our ancestors, we’re eating unbelievable amounts of fat and sugar, and just not enough fiber.

[…] these findings may be telling us that we need that high-fiber intake, not just to prevent food allergy, but possibly other inflammatory conditions as well.”

Co-senior author Prof. Charles Mackay, Monash University

Read about how the increase in childhood food allergy is not matched by an increase in food sensitivity.