The “Hygiene Hypothesis” – Celiac Disease & Bacteria

KidInDirtYou might be surprised to learn about a possible linkage between celiac disease and bacteria, especially because it turns out that more exposure to germs at an early age may actually help prevent celiac disease. There actually is evidence indicating that the increase in sanitary conditions in many areas of the world may be one of the reasons for the rising rates of celiac disease.

This idea even has a title, the “Hygiene Hypothesis,” and it applies to more than celiac disease. Basically, the hypothesis is that the immune systems of very young children need to be stimulated by a certain amount of germs that have been present in the environment over the centuries. This exposure leads the immune system to help learn to distinguish what it needs to attack (bad bacteria) as opposed to what it shouldn’t attack, such as foods containing gluten, parts of the body, and “good bacteria.”

As sanitation improved significantly throughout the 20th century, babies were exposed to fewer bacteria and other infectious agents. The dirt was less “dirty” and children played in it less and under more supervision in many parts of the world. Parents today are much more likely to clean up a child who puts dirt in his mouth and try to stop him from doing it again. Water is freer of germs, and houses are cleaned with a lot of anti-bacterial soap.

This is not all bad. Diseases like dysentery and parasitic infections are less common in developed countries. However, autoimmune diseases and allergic reactions seem to be increasing.

Studies with information that supports the hygiene hypothesis are accumulating. One in particular stands out. There is an area at the Finnish/Russian border called Karelia that used to be one province, and was arbitrarily split between the two countries, Russia and Finland. The people living on each side are genetically similar and could be expected to have similar rates of celiac disease.

They do not. Those on the Finnish side have the 1% risk now common to most European countries. The Russian Karelians have one fifth the risk, with one in 500 people getting celiac disease.

The Russians now eat more wheat than the Finns, so the difference has nothing to do with exposure to gluten, and as noted, genetics differences are unlikely. However, the people living on the Finnish side have a per capita income 15 times that of the Russians. The Finns have a better diet and more sanitary living conditions. The Russians live like the Finns did half a century ago.

Researchers speculate that the improved living conditions stop early exposure to many infectious agents that used to be commonplace in the area. There are actually measurably more germs in the drinking water and house dust in the Russian part of Karelia than the Finnish part. Children on the Finnish side have more kinds of bacteria in their intestines.

If the hygiene hypothesis is correct, it may explain the increased incidence of celiac disease on the Finnish side of Karelia. It might also explain why there is six times less type 1 diabetes, as well as a lower rate of allergies and autoimmune thyroid disease on the Russian side of the border.

In addition to collecting information about this hypothesis, researchers are suggesting some ways to help introduce babies to the right kind of bacteria. This can be done by giving them probiotics, which are active “good” bacteria that have been proven safe and helpful in preventing and treating a number of conditions. One called Bifidobacteria infantis exists naturally in breast milk.

It should be noted that infants who come down with a number of illnesses caused by certain other viruses and bacteria may be at greater risk of celiac disease, if they have the genetic tendency. These are different germs that cause specific diseases as opposed to just stimulating the immune system like “good bacteria.”

A recent study found that giving these bacteria to adults with CD lessened their symptoms. Other research is being done. In the future, infants at risk for celiac disease may be treated with probiotics.

No one wants to turn back the clock on improved sanitation and better diets, but there may be some things that have been lost that need to be returned to the lives of young children to prevent celiac disease as well as other autoimmune disorders.

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References
Velasquez-Manoff M. The New York Times Sunday Review. February 23, 2013.
Smecuol E, Hwang HJ, Sugai E, et al. Exploratory, randomized, double-blind, placebo-controlled study on the effects of Bifidobacterium infantis natren life start strain super strain in active celiac disease. Journal of Clinical Gastroenterology. 2013 Feb; 47(2):139-47.
 
 

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