C&B Notes

Microbiome As Our New Organ

Evidence continues to mount in favor of the microbiome’s importance to human health. We may not be what we eat but rather what our gut bacteria are.

During the first few months of life, the microbe community in our bodies is considerably less established and stable than later in life.  Any drastic changes to it have a much higher chance of permanently altering our microbiota (as specialists call this world of tiny organisms within us) and our long-term health.  From the moment we are born, we begin getting colonized by bacteria, which kick-start a series of fundamental biological processes, including the development of our immune system.  Before birth, the lining of our gut is full of immature immune cells.  When bacteria move in, the immune cells react to them, changing and multiplying.  They even move to other parts of the body to train other cells with the information they have acquired from these intruders.  If deprived of this interaction, the immune system remains sloppy and immature, unable to fight off diseases properly.

Scientists haven’t figured out exactly how microbes do this at the molecular level, but we do know that most bacteria will teach these immune cells to tolerate them, whereas some bacteria — the pathogens that cause diseases — prompt strong resistance.  The result is to make the intestine a relatively controlled and harmonious place.  Another fundamental function of microbes is to aid in the regulation of our metabolism.  Like other animals, humans obtain energy from food that is digested and absorbed in the intestines.  Besides helping us digest certain foods that the intestines can’t handle on their own, bacteria produce compounds that help to define how we use or store energy in our bodies.  New research also shows that our microbiota plays an important role in neurological development and even in the health of our blood vessels.

Such discoveries have led scientists to call our microbiota a “new organ,” perhaps the last human organ to be discovered by modern medicine.  Most of this knowledge is still relatively new and many pieces of the puzzle remain unsolved, but protecting the initial developmental stages of our microbiota clearly has a significant impact on our health.  Inflammatory diseases (such as asthma, allergies and inflammatory bowel disease) and metabolic diseases (such as obesity and diabetes) are characterized by alterations in our immune system and our metabolic regulation.  Knowing what we do now about the role of the microbiota, it is not surprising that these diseases are being diagnosed in more children.  They are, to a great extent, a consequence of relatively recent changes in our lifestyle — modern diet, oversanitization, excessive use of antibiotics — that have altered the specific microbes that affect our metabolism early on.  We urgently need to find ways to modify our behavior so that our microbes can function properly.

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What to do about it?  The U.S. Food and Drug Administration took one helpful step earlier this month when it banned some chemicals used in antibacterial soap, but the most important changes need to take place in our everyday routines.  Parents can expose their children to an array of microbes by encouraging them to spend time outside, like our friend Julia on her farm (but not necessarily with chicken and pig waste).  Today children spend much less time outside than they did only 20 years ago.

Babies and toddlers often aren’t allowed to play in the dirt or sand, and when they are, they are wiped clean immediately.  Phrases like, “Yuck! Don’t play in the mud!” or “Don’t touch that bug, it’s dirty!” have become second nature.  We need to unlearn these habits.  By preventing babies and children from following their innate impulse to get dirty, we shield them from the microbial exposure that is essential for the development of a healthy immune system.  Parents can also promote good gut-health in their kids through diet.  It is well established that the Western diet — high in fats, sugars and highly refined grains — is very strongly associated with a number of diseases, especially obesity and the closely linked disease of type-2 diabetes.  Our ancestors grazed on a variety of foods, which ensured a variety of microbes in their intestines: Eating a range of different foods provides a hospitable environment for a range of different microbes.  Today, 75% of the world’s food comes from just 12 plant species and five animal species.  Amazingly, just three species — rice, corn and wheat — account for 60% of the calories that humans obtain from plants. Except for regions where a lack of economic development has preserved older farming and dietary practices, more people are eating refined white sugar, white flour and processed fats, instead of our ancestral diet of vegetables, fiber, fruit and nuts…

Food isn’t the only way that we have altered our microbiota, however.  Our microbes have perhaps taken the biggest hit from one of the best things humanity has ever invented: antibiotics.  These wonder drugs have saved millions of lives and will save millions more in the future.  But antibiotics aren’t targeted missiles that kill only the bad bacteria causing infections; they are carpet bombs that kill good and bad bacteria indiscriminately.  Research now suggests a link between the use of antibiotics in early childhood and problems such as obesity, diabetes, asthma, allergies, autism and inflammatory bowel disease.

We ought to become more restrictive with the use of antibiotics in children.  Parents shouldn’t assume that all infections have to be treated with these drugs.  Upper respiratory tract infections and colds are often caused by viruses, so anti-bacterials won’t cure them.  Most sore throats, especially if the child also has a runny nose and cough, are caused by viruses and don’t need antibiotic therapy.  If a child has a mild ear infection, it’s reasonable to watch and wait for a few days to see if it gets better on its own before starting antibiotic therapy.  Also, parents should consider giving probiotic supplements (with live bacteria and yeasts) to a child if he or she is being given antibiotics.


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