A Healthy Gut May Resist Allergies, Asthma

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A Healthy Gut May Resist Allergies, Asthma

Keeping Helpful Bacteria and Fungi in Balance Is Key, Say Researchers

By Miranda Hitti

WebMD Medical News Reviewed By Brunilda Nazario, MD

on Thursday, December 23, 2004

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Dec. 23, 2004 -- Allergies and asthma may start in your gut. Upset

the gut's natural mix of helpful bacteria and fungi, and allergies

and asthma may develop.

According to researchers, the rates of allergies and asthma have

increased. They say this correlates with increasing antibiotic use

and possibly relates to the hygiene theory. This may mean that

modern practices of sanitation could deprive people of defenses

needed to prevent asthma and allergies.

That theory was recently tested on lab mice. First, the mice drank

water laced with antibiotics for a few days. This disrupted their

microflora -- healthy bacteria and fungi found naturally in the

gastrointestinal tract. The mice got increasing numbers of fungal

inhabitants. Specifically, they had increased amounts of the yeast

called Candida, which is commonly seen after taking antibiotics.

Candida, like many other yeast, secrete molecules that affect the

immune system's response to allergens.

With their microflora out of whack, the mice were then exposed to

allergens. They promptly showed signs of allergic airway disease

similar to asthma.

But another group of mice weren't bothered by the mold. Their

microflora had been left alone. That suggests that allergies and

related breathing problems could start in the gut.

The study didn't stop there. The researchers pushed a bit further to

see if genetics or other allergens mattered.

They found that the genes of the mice made no difference, and they

saw the same effect with several other allergens (pollens, danders,

dust mites, and cockroach feces).

Change the microflora in the gut and you upset the immune system's

balance between being exposed to allergens and having a severe

reaction to them, says researcher Huffnagle, PhD, in a news

release.

Huffnagle is an associate professor of internal medicine,

microbiology, and immunology at the University of Michigan's medical

school. He worked on the study with Mairi Noverr, PhD, a

postdoctoral fellow at the University of Michigan, as well as

British colleagues.

The findings could apply to humans.

People need a mix of healthy bacteria and fungi in their guts.

Microflora in humans can be thrown off by antibiotics and a sugary,

high-fat, low-fiber diet. Swallowing also brings potential allergens

to the gut.

The researchers aren't against antibiotics. Instead, they want

people to know that eating a healthy diet with lots of fruits and

vegetables is important after taking antibiotics to restore

microflora as quickly as possible.

The study appears in the January issue of Infection and Immunity.

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SOURCES: Noverr, M. Infection and Immunity, January 2005. News

release, University of Michigan.