“Quick, pass me the disinfectant!”
Learning to love your body bugs
If there’s one thing that’s guaranteed to make your skin crawl, it’s the thought of tiny creatures living all over your body. We inherently think of bugs and ‘germs’ as evil intruders that need to be exterminated as quickly as possible. But while some bacteria do cause dangerous illnesses, such as pneumonia and meningitis, the vast majority of the 30 trillion microbes that coat our bodies are ’good guys’. From head to toe, we are quite literally plastered in bacteria and many of them contribute to our health and wellbeing. Small changes to this invisible world’s population of bugs — broadly called our microbiome — can have serious consequences. A disturbed microbiome has been linked to long-term health conditions, such as Type 2 diabetes, inflammatory bowel disease, depression, anxiety, and even obesity. Life is lived best with a healthy coat of bacteria, so it’s the time to stop squirming and stat learning to love your microscopic friends.
Could your bugs be making you fat and sick?
As a society, we are getting sicker, fatter, and unhappier. Type 2 diabetes, heart disease, and depression have been steadily on the rise for the past fifty years. This is partly because we eat too many McDonald’s meals and spend too many hours sitting on our behind. We all know that too much sugar and fat is bad for our health, but an unhealthy lifestyle is also bad for our microbiome.
For millions of years, animals have offered their bodies to bacteria as a well-furnished, nutrient-rich home. In return, these microscopic organisms have provided their host with some well-needed perks. We have evolved alongside bacteria and they seem to be intertwined to our survival, but scientists are only just beginning to work out how these microbes interact with each other and with us. It’s one of the fastest growing scientific fields and it’s turning into big business. Super-celebrities like Oprah promote microbiome products, including the ‘μbiome gut kit’, which for ‘a mere’ $89 gives you a ‘comprehensive breakdown’ of your microbiome. Some people are even going so far as to chow down on poo pills in an effort to give their microbiome a boost. Haven’t you heard? ‘Faecal transplants’ are all the rage in Hollywood.
Recent studies have investigated how the bacteria in our intestines (there are trillions in there alone) affect how our muscle and liver cells store nutrients and use sugars as energy. Some gut microbes encourage the body to put on fat and can influence how the body responds to insulin — the hormone responsible for regulating blood sugar. In mice, bacteria are also known to help regulate appetite and weight. Taken together, these findings suggest that our microbiome may affect how easily we put on weight. Remarkably, recent research has uncovered that slim people have different gut bacteria compared to obese people, offering a possibly explanation why some people find it so hard to lose weight.
The prevalence of asthma and allergies are also on the rise in developed countries. Some researchers think that our unbalanced microbiomes may be partly to blame. These disorders are triggered by an over-reaction of the immune system to harmless substances, such as dust, pollen, or nuts. Allergic reactions can be severe, and sometimes life-threatening, leading some schools and workplaces to take the radical step of banning peanut butter and perfume. Wrapping ourselves in cotton wool may not be the solution, however, and a super-clean environment may be part of the problem. The ‘hygiene hypothesis’ — a theory that became popular in the early 90s — states that widespread use of bug-busting cleaning products and antibiotics prevents children being exposed to both ‘good’ and ‘bad’ bacteria, leading to a weakened immune system. This theory is supported by the fact that in countries where powerful cleaning products are less widely used, bacteria set up home in newborns earlier (yes, that’s a good thing) and rates of allergy and asthma are lower. Data shows that children given antibiotics are also more likely to develop allergies and asthma. Some healthcare professionals are so convinced by this evidence that they are reconsidering the use of antibiotics to treat mild infections altogether. Next time you reach for the bleach you may want to ask yourself: “Too clean or not too clean?”
A poorly tummy and a poorly mind
Inflammatory bowel diseases (IBDs), like Crohn’s disease and colitis, rarely get much attention but they are truly horrible conditions. They typically cause bouts of painful inflammation in the intestines, often for months at a time. Sometimes drastic treatments, such as cutting out sections of gut, is the only way to get symptoms under control. Yet despite its severity, the causes of IBDs are largely unknown. A new school of thought, however, now points the finger of blame at an unhealthy microbiome. In a 2012 study, doctors discovered that patients with IBDs had a less varied gut microbiome compare to normal. The bacteria that were in the intestines of IBD patients were more likely to irritate the gut by releasing molecules that inflame the inner lining of the intestines and loosen the tight connections between cells in the intestinal walls. Large molecules from semi-digested food can leak into the blood stream, causing the body’s immune system to attack elements of the digestive system. Conversely, ‘good’ bacteria, such as the catchily-named Bacteroides fragilis, do the opposite by producing molecules that protect against IBD. Current treatments for IBDs involve the use of powerful drugs that suppress the immune system, but one day a bit of healthy bug growth could offer a more palatable remedy.
One of the most unexpected discoveries of recent times has been finding that the microscopic organisms we share our body with can impact our mental health. Experiments on mice have shown that an upset microbiome can cause insomnia, restlessness, lack of motivation and even fear. Gut microbes can manufacture a wide range of chemicals that influence our nerve cells and can act on the brain via a long nerve called the vagus nerve, which connects the brain to the gut. Mood-altering bacteria secrete substances very similar to those the body uses in the brain — such as dopamine and serotonin. Some doctors have started to try to use ‘good’ bacteria to re-establish a healthy gut microbiome, believing it may be a potential treatment for certain neurological disorders. It sounds a long shot but — who knows? — pretty soon we might all be saying, “A probiotic a day keeps the psychiatrist away.”
This article was written by Jessica Bertschmann and originally appeared in Guru Magazine. Jessica is a fourth-year medical sciences student at the University of Western Ontario. This essay is the product of a science-writing internship in David Smith’s Lab at Western.
