Imagine a world with no bacteria. No bubonic plague or tuberculosis. No staph in the locker room or anthrax in the news. These changes might seem welcome at first, but not all bacteria are killer scourges that propagate disease and decimate populations. To the contrary, a team of scientists led by Dr. Li Wen of Yale Medical School has uncovered startling evidence of bacteria playing frontline defense against a formidable opponent — type 1 diabetes.
Type 1 diabetes — unlike type 2, which is associated with unhealthy lifestyle choices — appears in childhood and is an autoimmune disorder. This places it in the company of respiratory allergies, asthma, multiple sclerosis, and rheumatoid arthritis, disorders in which the immune system malfunctions and attacks the body’s own cells. While these are largely genetic in origin, scientists have noticed that the rate of autoimmune disorders is much higher in developed countries. For example, the U.S. rate of new type 1 diabetes cases is well over ten times that of China. This sharp disparity suggests that environmental factors must also be in play. But why would a clean, developed environment lead to more diabetes?
Dr. Li Wen was already studying diabetes before she came to Yale 15 years ago, and while her research was focused on various genetic indicators of diabetes, she soon became interested in the missing link between diabetes and the environment. Dr. Wen examined the work of researchers who, while studying allergies two decades ago, hypothesized the existence of “friendly” bacteria that help the immune system function properly – bacteria which are scarce in the sterilized environment of a developed country. She became determined to test this hypothesis for type 1 diabetes.
To do so, Dr. Wen and her team studied two groups of mice that were genetically predisposed to develop type 1 diabetes. One group was raised from birth in an entirely germ-free environment; the other group was routinely exposed to harmless bacteria normally found in the human gut. The researchers found that the exposed group had a decrease of more than 50% in the rate at which they developed diabetes, resulting in a disease that progressed slower, occurred less frequently, and was less severe than that of the germ-free group. “I’m not saying that the bacteria prevented diabetes completely,” Dr. Wen noted. “But the reduction was huge.”
In her opinion, this was unequivocal evidence that “friendly” bacteria could modulate the immune response, making autoimmunity problems less likely. “It’s like our immune system needs target practice,” Dr. Wen offered as an analogy. “When there are so few bacteria around, it’s more likely to start attacking our own body.”
So if germs can push down rising rates of autoimmune disorders, should we boycott anti-bacterial soap and start taking dirt baths? “You can’t tell people to not wash their hands,” Dr. Wen cautioned, “and you can’t tell hospitals to not sterilize their equipment – the risks are too great. But if the findings of this study hold true in humans, there are definitely other habits that people should change for the better.”
One of her suggestions was simply to get more fresh air and sunshine — along with an extra dose of beneficial germs from the great outdoors. Dr. Wen implied that the sedentary lifestyle of many Americans — staying cooped-up in hygienic homes and offices all day — could be a large contributor to the rising severity of allergies and the up-tick in diseases such as type 1 diabetes.
Similarly, Dr. Wen’s findings may point to a wider beneficial role for “probiotic” foods such as yogurt products, certain cheeses, and miso soup, whose health claims are abundant but relatively unverified. These foods contain a small amount of live bacteria, which are harmless and are already thought to aid in digestion. Now, there is even the possibility that these bacteria, along with the foods they inhabit, might also confer protection from a huge spectrum of autoimmune disorders.
But don’t be mistaken. The existence of “friendly” bacteria changes very little about how we should fundamentally care for our bodies. If anything, the research conducted by Dr. Li Wen highlights, more than ever, the delicate balance of biology that keeps us in good health. So go ahead. Go outside and tumble in the dirt for awhile. Just don’t forget to wash your hands when you’re done.