Penicillin, strawberries, eggs, peanuts—the allergy list goes on. More and more people seem to suffer from allergies. Now one researcher thinks a solution may literally lie in the dirt.

Dr. Cosby Stone is an immunologist and allergy researcher at Nashville’s Vanderbilt University Medical Center. He studies medication allergies and allergy prevention. According to Stone, genes explain less than half a person’s allergy risk. But if genetics don’t fully explain allergies, what else causes them?

There are two theories: the barrier hypothesis and the hygiene hypothesis.

The Barrier Hypothesis

God began building your immune system before birth. (Psalm 139:13) Imagine that system is an army behind a castle wall. The wall (“barrier”) is your respiratory tract, digestive tract, and skin. The army is made of white blood cells and other cells. They are designed to attack threats to your health.

When your barrier wall gets injured, immune system soldiers try to defend you. But allergens can penetrate a weak barrier, and allergies flare up in the broken-down areas.

Many things—diseases, pollution, nutrient deficiency, food absorption disorders—can harm the barrier. They can cause damage to the lungs, intestines, skin, etc., and increase the risk of allergic responses.

The Hygiene Hypothesis

This theory says that humans have accidentally killed off good bacteria alongside bad. As our ultra-clean society removes diseases caused by filth—with measures such as bathroom hygiene and water sanitization—humans reduce how much their immune systems practice fighting disease.

Overuse of antibiotics is another culprit. Too much of a good thing may kill off both good and bad bacteria. In other words, good things like antibiotics and sewage and water treatments may have kicked off an allergy epidemic. The human immune system no longer gets the practice of a workout, fighting off smaller-scale germs. 

Vaccinations appear to be an exception to the hygiene hypothesis. Stone says vaccines protect against diseases without increasing allergic disease risk. Unlike antibiotics—which attack bacteria and sometimes the body too—vaccines cause the body to turn on its own germ-fighting powers.

Studies show that growing up in rural areas exposed to germ-carrying farm animals may decrease the risk of allergies and asthma. Mice studies reveal that inhaling molecules from some soil-dwelling bacteria can promote an immune system that better handles allergens.

The Current Rx

Not everyone can live on a farm. Researchers are studying how people could prevent allergies by protecting their “barriers”—while allowing exposure to certain allergens, such as peanuts and other things, very early in life. For now, no one can say how much dirt or what kinds of bacteria a child should experience while growing up. But scientists are working on these questions.

Until then, Stone gives this broad advice:

● Children should play outside, get dirty, and try new foods as much as possible.

● Plain soap and water work best.

● Don’t sanitize everything.

● Use caution in taking antibiotics.

● Get routine vaccinations against serious illnesses.