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Tuesday, August 21, 2012

The Microflora Hypothesis

The following post was published July 11, 2011 on

The Mocroflora Hypothesis of Allergies and Asthma

It's a proven fact asthma rates are on the rise in Western nations like the U.S. and U.K.  In the past pollution was blamed.  Yet with pollution on the decline and asthma rates still rising, many experts are looking at other theories.

Two theories gaining acceptance are the hygiene hypothesis and the microflora hypothesis.

The hygiene hypothesis pretty much proposes allergies and allergic are caused because we're too clean.  In the absence of bacteria our immune system gets bored and attacks things we consider normal -- like allergens.

I simplified the hygiene hypothesis in a previous post.  If you're not familiar with it I recommend you click here.  In this post I'd like to introduce you to the microflora hypothesis.

First a few definitions:

Normal Flora:  According to the Online Textbook of Bacteriology these are tiny little microbes that cover the surface areas of your body, including your skin and mucus membranes.  This consists of some fungi, but mostly bacteria.  Their main job is to prevent the growth of bad bacteria.

Microflora:  According to these are normal flora of a specific location, such as the intestines.

Probiotics:  This is simply a synonym for normal flora.

So what is the microflora hypothesis?

It's actually similar to the hygiene hypothesis only it goes a step further.  It states microbes in your intestinal tract (microflora) work together with your immune system to keep your immune system working right.

An imbalance of these microbes any time in your life can cause your immune system to develop an inappropriate response.  This may best explain why asthma can be developed at any time in your life.

So what causes microflora to become imbalanced?

Two things in our modern, industrialized way of life are suspected to cause such an imbalance:
  • 1. Antibiotics
  • 2. Dietary changes
So, how might antibiotics cause an imbalance of microflora?

Antibiotics:  These were considered to be a godsend to the medical field when they hit the market in 1944, as they allowed doctors to treat and prevent infection. While these are good, there are consequences to antibiotic abuse:
  • Some bacteria are smart: They catch on and develop resistance to antibiotics and this forces us to invent more powerful antibiotics.
  • Some antibiotics kill too much: Instead of killing just the infecting bacteria we were also killing the good bacteria we need to maintain balance
  • Antibiotics only kill bacteria: Actually we knew this all along, but I just thought I'd add it here to make a point.
While antibiotics are only able to treat bacterial infections, they were -- and often still are -- prescribed to treat any infection, even viral.  Often they are ordered just so you think the doctor is doing something.  You have asthma symptoms; you have a cold, so you expect antibiotics.

In fact, this study shows that way too many asthmatic kids are being prescribed antibiotics to treat asthma even though doctors know they aren't recommended in the treatment of asthma.  It's expected many doctors order them just to "cover their bases."

Yet it's a common fact the most common asthma triggers are viral infections.  So treating your sickness with an antibiotic is useless unless you really have a bacterial infection.

The most common antibiotic prescribed would be broad spectrum antibiotics.  These kill more than one type of bacteria, yet the hope is they'd kill the culprit.  The problem with these is they kill the good along with the bad.

Narrow spectrum antibiotics can also be prescribed.  These are antibiotics that only kill the desired bacteria.  Yet to prescribe them in the office without further testing would be a crap shoot.  To pick the right one you're sputum must be tested to identify the bacteria.  If no bacteria are identified, antibiotics will be useless.

If bacteria are identified further testing can be done to see what antibiotic kills it.  In this case, a broad spectrum antibiotic can be selected.  The problem with all this is it takes time and money.

So most often your doctor will skip all this testing and just give you the antibiotics you want.  You're happy, he's covered all his bases, and you eventually get better.

The solution to this problem might be simple:
  • Avoid antibiotics use.
  • If antibiotics are needed,narrow spectrum antibiotics should be used.
Modern diet:  According to The Probiotic Revolution, "people in industrialized countries eat significantly more fast food and refined foods, and much less fiber.  They're also less likely than people in the developing world to rely on fermentation to preserve goods -- thus depriving themselves of a ready source of probiotics."

The solution to this problem might also be simple.  Eat more of the following:
  • Whole grains
  • Nuts
  • Fruits
  • Vegetables
  • Probiotic supplementation
Probiotic supplementation:  As far as a cure for asthma and allergies, some studies have been ongoing to determine certain therapies can be done to restore the imbalance of probiotics in the gut. Studies are ongoing to see if this prevents or treats allergies.

Since 75 percent of asthmatics also have allergies, the hope is probiotic supplementation will also prevent and treat asthma as well.  Studies are ongoing, and we'll have to wait and see how they turn out.

So there you have it:  the microflora hypothesis.  It's one of several theories of what might cause one to develop asthma.  What do you think?

Click here for a more in depth discussion of this hypothesis. 


Brian C. said...

Congratulations Dr. Frea. Your blog has been chosen to be featured on's list of Top Respiratory Therapy Blogs:

We felt that your blog offers invaluable information and guidance to those interested in and practicing RT.

We hope you continue to be a valuable resource for everyone in the RT space! Feel free to share the great news and accomplishment on your blog or any other channels you utilize. It's much deserved!

Anonymous said...

The patients themselves want the antibiotics as well. Patients are seeing antibiotics as a miracle drugs that can cure all diseases. There's a lack of education on how antibiotics works. It's common to hear people saying "How to get well if there's no antibiotics?" when they are down with a cold or flu, when most of the time flu or cold is due to virus infection.

I have always thought the misuse of antibiotics is an issue in Asia only.