Allergies seem to have a specific purpose: to keep our immune system active. Is this an area we should meddle with? And if so, how? Is there a connection to cancer?

This post examines the interrelationship between allergies, the immune system, and cancer. It raises more questions than it has answers. Anyone with answers or opinions, please weigh in.

Allergies are an overreaction to items that aren’t usually harmful. Of course, in the case of anaphylactic shock, the allergic reaction can be fatal, and the allergen must be strictly avoided. However, most allergic reactions are mild: sneezing, itching, eczema, etc. But why do we have any reaction at all?

The Hygiene Hypothesis

Actually, this is so widely accepted, it should be called the Hygiene Dogma. The idea is that in Western societies, with many pathogens under control, the immune system has little to do. Therefore, to keep in shape, it indulges in immune system reactions to harmless items. There is substantial support for this. It is known, for instance, that children in large families have a lower amount of hay fever than only-children. Further, allergies are less prevalent in the developing world. In fact, when people emigrate from the developing world to the industrialized world, they tend to “get” allergies.

So, let’s presume this dogma is correct. Is seems logical and has plenty of supporting evidence. What is not clear at all, though, are the long-term health implications. We obviously need a functioning immune system. The sad fate of AIDS victims is a well-known example of the dangers of compromised immune systems.

Additionally, many of the chronic or degenerative diseases associated with aging, cancer in particular, are caused or exacerbated by a weakened or weakening immune system.

Not everyone has allergies—why is that?

Not known. Of course it is always possible that a person could have some sort of chronic infection or parasite—something to keep the immune system busy, but it also seems that many people who have no such problems simply do not have allergies.

The immune system and cancer

In the case of cancer, there are two factors at work. First, the number of defective cells increases as we age, increases if we drink, if we smoke, or if we are exposed to industrial toxins. Second, with age, the immune system weakens. So eventually a tipping point is reached and cancers can occur. We can—and most will—make changes to reduce the number of defective cells. Exercise, real food, etc., will accomplish this.

The immune system of allergy sufferers apparently feels underworked. Many bodily functions—most really—follow a “use it or lose it” rule. Muscles shrink if underused, bones weaken and so on. This is largely an energy conservation survival strategy.

Does the immune system also weaken if underutilized? The idea that it starts allergies just to stay in shape would suggest this. But is it already weakened when the allergies show up, or is it keeping itself in tip-top shape? We do not know the answer, but would like to know because the immune system monitors and removes defective cells, and, when the immune system can no longer do this, defective cells become tumors.

It is therefore entirely possible that weakening of the immune system is partially responsible for the increased cancer rates. Our sanitary ways are eroding our immune system—a sinister thought in many ways.

Allergies and cancer

Now here’s where it gets really interesting: People that get allergies get less cancer.

A study reported here finds reduced rates of pancreatic cancer among allergy sufferers. Similar findings were reported here, with the most reduction occurring to those allergic to cats!

An old, but large, epidemiological study, found here, has somewhat mixed results: allergy sufferers had a significantly decreased risk for kidney, stomach, and bladder cancer, but an increased risk for prostate cancer. Colon and lung cancer were unaffected.

In a review paper found here, we have, “Individuals with any type of allergy have a decreased risk for cancer (compared with the general population), including glioma, colorectal cancer, cancer of the larynx, non-Hodgkin lymphoma, cancer of the esophagus, oral cancer, pancreatic cancer, stomach cancer, and uterine body cancer. However, an increased risk for bladder cancer, lymphoma, myeloma, and prostate cancer exists among those with allergies.”

There are a lot of results and they are rather consistent. That allergy sufferers have a reduced risk of several cancers seem solid. Why is there a connection between cancer and allergies? The immune system is the link, of course, but what is it exactly? It would seem likely that people with allergies have more active immune systems, and more active immune systems means less cancer. On the other hand, it is somewhat unexpected that allergies would have this desirable benefit. Allergies mean inflammation, and chronic inflammation leads to cancer as well. Still, amazingly, it seems that having allergies is, in general, a Good Thing.

Ways to boost the immune system

Allergies or not, boosting the immune system is a win-win.

The immune system is usually described as consisting of leukocytes, also known as white blood cells. However, circulating HDL, the so-called good cholesterol, behaves in many ways as an immune system member. In particular, it improves the cellular environment, directly siphoning off cellular toxins and so forth. Healthier cells have fewer defects, which means fewer cancers. An HDL boost of 10 mg/dl, something easily achievable with proper exercise, reduces cancer 36% (and heart disease a whopping 50%). HDL will even directly help out the macrophages (immune cells that actually swallow the unwanted junk) by relieving them of their toxic contents.

Ok, fine and dandy, let’s boost HDL with exercise. But can we also improve the health of the leukocyte cells that make up the immune system? Maybe. If you Google the topic you will find the usual overwhelming number of claims to this effect. There is also (as usual), a near universal absence of information on exactly how the proposed food or supplement would actually improve the immune system health. Usually the claim has something to do with vitamins. A vitamin deficiency will certainly compromise any cell, including those of the immune system. However, excess vitamins cause similar problems. This is an area best left alone. The body will extract the optimum level of vitamins from the food we eat, given sufficient choice (food quality and variety). So eat colorful vegetables and cleanly raised meats. And, of course, exercise has numerous cell rejuvenating properties.

But are there other ways to rev up the immune system? The scientific literature doesn’t seem to have much to say about this. There is talk of more and more vaccines, but this may not be the way to go. Giving the immune system a vaccine is rather like doing part of its job. Of course, we want to avoid the deadly diseases, but do we really ant to vaccinate against, say, the common cold? Or let the immune system flex its muscles and figure it out for itself?

What should we do, if anything? Should we workout the immune system like we do the rest of our body? Stop washing hands, or stop washing fresh vegetables? There’s a movement in this direction as well, though their evidence is primarily anecdotal too. Should those of us with cat allergies go adopt a few cats? Or should hay fever sufferers go for a roll in the hay? If this seems confusing, you are not alone. Unfortunately, we just don’t know, but keeping that immune system active and on the job is very key to a healthy old age.