In an interview with me, Dr. Charles Raison, University of Arizona School of Medicine, with a joint appointment in the School of Agriculture, discussed the shocking hypothesis that we are sicker because we are too clean. At the risk of doing heedless damage to his well-articulated ideas, I will try to explain.

There are a number of illnesses that fit the pattern of clean-leads-to-illness, but I will focus on depression. Depression rates have clearly increased over the past one hundred years. Various explanations have been offered, such as psychological ones like learned helplessness or increasing social stress, or biological ones such as the increase in obesity, the prevalence of pro-inflammatory fast foods, and reductions in Omega-3 content in modern food.

But no one suspected cleanliness as a cause. At least, not until recently, with a new line of research originating with the strange observation that there was more asthma in children raised in clean homes with no pets. This insight has lead to some new directions in immunity and robust physical health. Since then, a number of illnesses are clearly shown to increase with cleanliness, including depression. Not all depressions are associated with inflammatory factors, but many are, and those seem to arise from the modern clean lifestyle.

Clearly we live longer lives because of cleanliness. Many of us have studied the case of a cholera epidemic that was cured by removing the pump handle from a public water well in London. When people couldn’t get their water from that contaminated well, the epidemic resolved itself.

Cleanliness does work, and it works very well. When we study families of the 18th and 19th Centuries, it is common to see a woman bearing ten or more children, many dying in infancy or youth. What today is a terrible tragedy, the death of a child, was horrifyingly common in those days. Yet, there is another side to this story.

Raison and many other researchers have been looking at germs from a new point of view. Rather than avoiding all germs, they say, there are certain types of germs, that they call “The Old Friends,” that actually serve to educate our immune system. When we are exposed to these Old Friends during our youth, our immune system quickly develops a competent immunity to them. These are germs that are not dangerous and a child’s immune system quickly masters them. The immune system learns to be more tolerant, and the child is much less likely to get autoimmune types of illnesses.

But when we don’t get that exposure, our immune system is like a small dictatorship with a large army, looking for someone to fight. Our bodies begin to fight harmless substances in the environment such as pollens, dust, pet dander, and the like.

For example, Raison explained, hay fever was unknown before the 18th Century. When physicians started documenting it, they looked at it as a rich person’s disease. The poor never got that illness. Only the rich lived in such a clean setting that their children’s immune system didn’t get that vital education and were at risk for allergies and asthma. Other diseases like Crohn’s disease, irritable bowel, and Type 1 Diabetes also increase with more cleanliness.

There are two kinds of “Old Friends” that researchers have identified. First, there are probiotic gut flora, bacteria that live in the digestive tract and actually help the host digest and assimilate food. Eating fermented vegetables like sauerkraut or dairy products like yoghurt helps populate the gut with these friendly folks.

The other type of Old Friends are bacteria that don’t help, but don’t exactly harm us either. They are all around in primitive environments, and the immune system quickly develops immunity. It is a lack of exposure to these friendly or neutral germs that leaves our immune system with a hair trigger.

Our genome doesn’t contain all the instructions needed to help us be healthy. In fact, it cannot. Instead, we have evolved with these Old Friends, using them to educate our T-cells. Our body learns to tolerate these germs. Our immune system stays quiet. It doesn’t over-react.

There are many germs – bacteria, viruses, and worms – that researchers call pseudocommensals because they are present in the soil (from animals and animal feces) and on unwashed food. They do not colonize in the body. They pass through the gut, teach it a thing or two, and are gone.

Interestingly, there is solid evidence that having a less jumpy immune system even makes us less anxious and more able to connect socially. Certainly autism is increasing, and there appears to be some relationship benefits with these immune system educating germs. Perhaps growing up on a farm makes us less likely to play hours of World of Warcraft and instead wander over to the neighbors to share some gossip.

Dr. Raison mentioned that one excellent source of these helpful germs is a cow. But our zoning regulations and our modern lifestyle make keeping a cow an unlikely thing to do.

Cats are somewhat risky because of toxiplasmosis, a dangerous disease to pregnant women. But dogs and birds seem all right.

Now when I become King of the World, I will encourage people to keep cows, helping the children through exposure to cow dung and raw milk from healthy critters. But, you protest, a single cow gives more milk than a modern family of 3.7 persons can use. Certainly. So what about a neighborhood cow? A nice little Jersey cow will produce enough milk for several families, and they could all share in the care. A small breed like a Dexter would also work. But my grandfather’s Jersey was a kind and patient cow who nourished us with pure, rich milk. I remember her with love.

Our modern world lives in terror of the sound of a rooster crowing before the dawn is noticeable. But a family can keep a number of hens, which are quiet and generally pleasant creatures, depending on the breed. Leghorns are notoriously ill-tempered. A dog around the house is an excellent burglar alarm. And you can feed him your nasty leghorns while you keep the friendlier chickens yourself. Little children gathering eggs, drinking milk from the family cow, and playing with the burglar alarm are exposed to Old Friends and less likely to suffer from modern diseases, including depression.

If you are interested in listening to the interview, go here and learn more about it. I am determined to make this website start to pay for itself, and I want to offer Chuck Raison a reward for being such a great interview, so I will charge you a small fee.

Copy and paste this link if the above doesn’t work in your browser:

As much as I hate to admit it, the hippies were (partly) right. We should get back to the land and live a more natural lifestyle.  At least take your small children to heritage farms where they can wander among the chickens and geese and cows. Keep a garden, and eat your own veggies. Consider a few hens. While cats are a risk for pregnant women, other animals might be just what your child needs. Rescue a dog from the pound.

Good health to you!