If you catch a child with a finger up his nose, you probably discourage it. But could the "nasty" habit of nose-picking -- and eating it -- be more sanitary and even health-beneficial than we've been taught?

A biochemist from the University of Saskatchewan has theorized that nasal mucus -- commonly known as boogers -- has a sugary taste that's meant to entice children to... have a snack. But this may actually help introduce pathogens into the child's immune system that will strengthen their body's natural germ defense.

Other experts believe this theory (which has yet to be tested) doesn't necessarily hold water, since people swallow nasal secretions every day, even in their sleep, even if they don't eat their boogers.

Still, our culture seems to be somewhat obsessive about cleanliness, especially regarding children. But scolding kids for this particular habit may actually be counterproductive.

"The Only Good Germ Is a Dead Germ" Isn't Exactly True

An interesting theory -- the "Hygiene Hypothesis -- may explain why certain allergies and diseases have nearly quadrupled in recent decades. The premise is that children raised in an environment devoid of dirt and germs are less able to build up natural disease resistance.

Much worse: the growing tendency to ply children with antibiotics, which can kill healthy gut flora. Scientific evidence indicates that both practices contribute to increased vulnerability to illness later in life.

But how could dirt and germs keep you healthy?

Your immune system plays two main protective roles. Specialized white blood cells called Th1 lymphocytes assault infected cells throughout your body. Th2 lymphocytes produce antibodies to block dangerous microbes from invading your body's cells in the first place, while using other white blood cells to drive allergic responses to foreign organisms.

How Dirt Helps "Pump Up" Your Immune System

At birth, an infant's immune system appears to rely primarily on the Th2 system while the Th1 system grows stronger. But the hygiene hypothesis suggests that the Th1 system grows stronger only through fighting infection or encounters with harmless microbes. Without such stimulation, the Th2 system flourishes and the immune system reacts with allergic responses more easily.

In other words, adults who never allow themselves or their children to be exposed to viruses, dirt, germs and parasites may be preventing their systems from kicking in natural disease resistance.

Allergies, Heart Disease and Depression Linked to "Clean Freak" Tendencies

If you're healthy, exposure to bacteria and viruses may serve as natural "vaccines" that strengthen your system and provide long-lasting disease immunity. If you don't experience a healthy exposure to germs in your environment, you may end up sick.

Health problems associated with the hygiene hypothesis include:

• Asthma

• Eczema

• Autoimmune diseases

• Heart disease

One study even determined that childhood exposure to viral infections could reduce later-life heart disease risk by 90 percent.

Even depression has been connected to early pathogen exposure via an inflammatory connection. Neuroscientist Charles Raison, M.D., observed:

Since ancient times benign microorganisms, sometimes referred to as "old friends," have taught your immune system how to tolerate other harmless microorganisms, and in the process, reduce inflammatory responses that have been linked to the development of most modern illnesses, from cancer to depression.

Your Immune System Dictates Whether or Not You Get Sick

If you're looking for further evidence that booger eating may not be so bad after all, consider that it's the state of your immune system that determines your health after germ exposure. In one study, when 17 volunteers were infected with a flu virus, only half got sick. Researchers found that certain changes in blood took place 36 hours before flu symptoms showed up.

While all the participants had an immune response even if they didn't get sick, the responses were quite different.

"Symptomatic" participants experienced antiviral and inflammatory reactions, which may have been related to virus-induced oxidative stress. But in the non-symptomatic participants, these responses were tightly regulated. The asymptomatic group also had elevated expression of genes that function in antioxidant responses and cell-mediated responses. The scientists noted:

Exposure to influenza viruses is necessary, but not sufficient, for healthy human hosts to develop symptomatic illness. The host response [emphasis added] is an important determinant of disease progression.

The bottom line? If exposure to booger bacteria can help strengthen your immune system, a case could be made for their consumption... or at least, not scolding when you find a youngster with a finger up his nose.

Fortunately, healthy germ exposure comes in other ways, too...

How to Avoid Being Overly Hygienic

If the hygiene hypothesis is true -- and there's mounting research that it is -- trying to keep your environment overly sterile could backfire and actually increase your risk of acute and chronic disease. You can avoid being "too clean," and in turn help bolster your body's natural immune responses by:

• Letting your child get dirty. Allow your kids to play outside and get dirty (and realize that if your kid eats boogers, it isn't the end of the world).

• Not using antibacterial soaps and other antibacterial household products, which wipe out the microorganisms your body needs to be exposed to in order to develop and maintain proper immune function. Simple soap and water are all you need to wash your hands. Antibacterial chemicals (typically triclosan) are quite toxic and have even been found to promote the growth of resistant bacteria.

• Avoiding unnecessary antibiotics. Remember: Viral infections are impervious to antibiotics, as antibiotics only work on bacterial infections.

• Serving locally grown or organic meats that do not contain antibiotics.

• Educating yourself on the differences between natural and artificial immunity, and making informed decisions about the use of vaccinations.

For more by Dr. Joseph Mercola, click here.