Do you think parasites and bacteria are bad for you?

Well, you may be surprised. Because after years of doing everything we can get rid of these “bugs”, medical researchers are now doing a major reversal.

As scientists are learning, there's a complex ecosystem of non-human life forms living inside of us. Organisms we used to consider to be “bad” may not be so bad after all. And dozens of studies indicate our relationship to these “trespassers” is much more complicated than we actually thought. In fact these organizations may even be critical to our comfort and health.

Specifically, when it comes to tackling the growing problem of autoimmunity and allergies, these former “bad boys” may turn out to be the best treatment ever.

Battling Autoimmunity With Old Friendships

Over the last two centuries, humans have gone through a dramatic revolution in how we live – and who we live with. As we moved away from farms and into cities … as industrialization reduced our exposure to animals, their poop and the microbes that come with them … we may have lost old “friendships” that that used to keep us well.

Certainly, in many ways improved sanitation and reduced exposure to some microbes and parasites have improved people's health worldwide. But on the other hand, we're discovering having a close, neighborly relationship to some of these “unhealthy” organizations may actually be good for us.

Epidemiological studies starting in the 1950's revealed that wealth and urbanization seemed to be connected with an increase in allergies and autoimmune disorders like asthma and Crohn's Disease. Studies tracking people immigrating from third world to first world countries or countries undergoing rapid improvements in sanitation have also noted increased rates of autoimmune disorders such as multiple sclerosis, type 1 diabetes, allergies, asthma, lupus and more. [1]

As scientists dug deeper into this seeming paradox, they came up with what they call the “hygiene hypothesis”. It seems that the more we improved sanitation and reduced our exposure to low-grade infections from certain bacteria and parasites, the more immune system forgot how to regulate itself giving us allergies and autoimmune problems.

In a pivotal study linking pinworm eradication to higher rates of allergies in the UK, Dr. Graham Rook refined this hypothesis. He pointed out these bacterial and parasitic bad guys might be more like “Old Friends” when it comes to our health. [2]

These organizations may actually play a positive role in the development of our immune system and help our body fight against harmful inflammation.

Help Fight Inflammation With These “Bad Guys”

Autoimmunity and allergies are marked by inflammation. They are essentially health problems where your immune system reacts inappropriately and places on high gear. And when your immune system does this you experience pollution and pain.

C-Reactive Protein (CRP) is a special protein associated with inflammation in the body. Doctors test for this protein to monitor inflammation in the body. Most people in developed countries test positively for CRP to varying degrees. Younger people in the US have an average CRP level of 9 mg / L. Older American women on average have a CRP as high as 2.02 mg / L. One-third of American adults have CRP levels above 3 mg / L. This level is considered a sign of increase risk for multiple health problems.

However, when people in developing countries are tested for CRP the results are very different .

Unless they're battling a severe infection, most people in these countries have close to zero CRP in their bloodstream. That's right. Most people in the developing countries studied had zero signs of inflammation. For example, in lowland Ecuador, the average adult CRP level (ages 18-50) was only.5 mg / L.

This is despite the overall higher rates of infectious diseases in these countries. [3]

Initially this made no sense to researchers. But with the hygienic hypothesis, a pattern started to emerge that supported an interesting theory some scientists call “ecological pollution.”

As the theory goes, when we were farmers and hunter / gatherers, our body still produced inflammation and a strong immune response for infections that had the potential to kill us like cholera or pneumonia. But at the same time our body learned to ignore lower-grade infections caused by certain bacteria or parasites that did not pose a significant threat to our health.

These “invaders” taught our immune system to cool down and not overreact. However, when we lost our relationships to these bacteria and parasites in our ancestral environment, our immune system lost its ability to check itself. Consequently when we lost these “old teachers”, our immune system started to attack our own cells in the form of autoimmune disorders.

Restore These Old Friendships

Most research indicates these critical friends start at birth or even earlier.

In one study comparing farming mothers to non-farming mothers, researchers discovered the umbilical cord blood of women who lived on farms had many more immune cells and signal molecules that tell the immune system to calm down. [4] Moms exposed to the rich microbial and parasitic ecosystem of the farm were passing their immune system's anti-inflammatory knowledge onto their children.

One large scale epidemiological study went a step further. After looking at 52 different populations, the researchers found people who lived in countries known for higher populations of certain bacteria and parasites also had higher rates of genes linked to preventing inflammatory. [5]

As these studies indicate, enjoying the benefits of these “old friendships” usually comes from relationships formed before or soon after birth.

But that does not mean those of us who have lived to “too” sanitary life are out of luck.

Doctors are increasingly using probiotic bacteria and prebiotics to help with autoimmune disorders like Inflammatory Bowel Disease (IBD). Bringing certain bacteria back into our gut sees to calm things down dramatically. [6] Prebiotics like chlorella have also been shown to help people ward off autoimmune problems like fibromyalgia, ulcerative colitis and allergies. These benefits may be due in a large part to chlorella's role in supporting the growth of probiotic bacteria.

When it comes to worms, researchers at Tuft's Medical Center have successfully treated people with Crohn's disease using doses of parasitic whipworm eggs. When the worms hatched, people experienced a significant decrease in symptoms and no major side effects. Since the whipworms are usually found in pigs, they do not survive in the human digestive track longer than 2 weeks. With this success and based on good results from preliminary research, they're now launching a clinical trial using worms to treat type 1 diabetes. [7]

The Big Picture In Rebuilding Old Friendships

The implications of this discovery about our valuable internal neighbors are huge. As Dr. Graham Rook, pioneer of the term “Old Friends,” explains in his research, many of the genes that regulate how our body developments and functions do not come from our own cells – but from the cells of other organizations that live inside of us .

As he and other researchers explain, our work to eradicate bacteria and parasites from our lives may have done much good. But it may also be doing us harm.

Of course there's a balance to be stuck. As Rook and many of his colleges have arguably fiercely, this is not a call to live in squalor and embrace all dirt. But it is a challenge to find a balanced way of living that allows us to cultivate a healthy internal ecosystem so we can enjoy better health and comfort as well.


[1] Okada H et al. The 'hygiene hypothesis' for autoimmune and allergic diseases: an update. Clin Exp Immunol. Apr 2010; 160 (1): 1-9

[2] Rook GA et al. Microbial 'Old Friends' immunoregulation and stress resilience. Evolution, Medicine, and Public Health 2013. Pp. 46-64.

[3] McDade TW et al. Eeary environments and the ecology of pollution. Proceedings of the National Academy of Sciences of the United States of America. Oct 16, 2012.

[4] Schaub B et al. Maternal farm exposure modulates neonatal immune mechanisms through regulatory T cells. J Allergy Clin Immunol. 2009 Apr; 123 (4): 774-82.

[5] Fumagalli M et al. Parasites represent a major selective force for interleukin genes and shape the genetic predisposition to autoimmune conditions. Journal of Cell Biology. 2009. 206 (6): 1395-1408.

[6] Shida K et al. Flexible cytokine production by macrophages and T cells in response to probiotic bacteria: a possible mechanism by which probiotics enter multifunctional immune regulatory activities. Gut Microbes. 2011 Mar-Apr; 2 (2): 109-14. Epub 2011 Mar 1.

[7] Clarke T. Pig parasite may help treat autoimmune disorders. Reuters Aug 30, 2012.