Does “A Little Dirt” Help Or Harm, vs Allergies?

We’re not talking about exposure to the allergen in question, by the way.

But first let’s mention that yes, that can help (albeit should be done under very controlled conditions only with appropriate medical professionals, in the case of things that can cause anaphylactic shock and death).

If you’re interested in that, see: Peanut Allergy Diagnoses Have Been Halved: What Did They Do?

But no, we really are talking about “a little dirt” where the dirt in question is not, itself, allergenic.

Natural inoculation

Researchers (Dr. Ruslan Medzhitov et al.) have found that early-life exposure to diverse microbes and proteins builds broad immune memory that shifts responses away from allergy-driving IgE antibodies, and towards protective IgG antibodies, reducing later allergic reactions (to anything).

About that “anything”…

Yes, it gives cross-reactive immune memory: exposure to many microbes and antigens created immune memory that protected against new, previously unseen allergens.

No, that doesn’t mean it’ll definitely prevent all and any allergies, it simply means it reduces the risk of all and any allergies.

How it works: cross-reactive adaptive immunity suppressed type II immune responses and reduced IgE-mediated mast cell activation.

Or, translating that from sciencese:

Why it works: immune systems trained by real-world environments respond to harmless real-world allergens in a balanced way, instead of overreacting.

You can read the paper in full, here: Environmentally driven immune imprinting protects against allergy

You may be wondering about general hygiene, and isn’t handwashing, use of sanitizer, etc, important to protect against disease? And yes, yes it is.

See also: The Truth About Handwashing

However, in the words of Dr. Medzhitov,

❝But the tradeoff is that our immune system is in this untrained, unprepared state, and otherwise harmless exposures trigger a pathological allergic response❞

So, does this “natural inoculation” mean we should skip vaccines?

No.

This is about encountering harmless microbes in order to train the immune system to respond in a balanced fashion to something that is neither wanted nor a serious threat.

With this kind of well-trained reaction, the body is more likely to be able to one day encounter a peanut and not immediately kill itself in response.

However, that’s about things that are not in and of themselves a serious threat (except insofar as the body might have overreacted to them)

There is an important difference between a peanut and a deadly virus that has evolved to take over the cells of your body until you die:

• In the case of a peanut, the ideal bodily response is “don’t worry about it”
• In the case of a deadly virus or bacterium, the ideal bodily response is “destroy it by any means necessary”

For more on that, see: Why Some People Get Sick More (And How To Not Be One Of Them)

Want to learn more?

For much more detail than we can go into here, check out this excellent book that we reviewed a while back:

The End of Food Allergy: The First Program To Prevent And Reverse A 21st Century Epidemic – by Dr. Kari Nadeau & Sloan Barnett

It’s worth noting that with regard to the first-named author there, the bio begins:

❝Kari Nadeau, MD, PhD, is the director of the Sean N. Parker Center for Allergy and Asthma Research at Stanford University and is one of the world’s leading experts on food allergy❞

We mention this, because there’s a lot of quack medicine out there [in general, but especially] when it comes to things such as food allergies. So let’s be clear up front that Dr. Nadeau is actually a world-class professional at the top of her field 😎

Take care!