The Ecosystem in Our Gut

It might seem odd to be getting a lesson about microorganisms from someone trying to improve weight and overall health, but bear with me.  There is tons of emerging science linking health to creatures that live in our guts, so it simply can’t be ignored.  Your large intestine is a haven for trillions of microbes (mostly bacteria) that make up your gut microbiota. These microbes form an ecosystem involved in vital functions like metabolism, hunger, and digestion.  Many scientists are now calling this collection of microorganisms a virtual organ – it is so intertwined with who we are and what we do.  And yes, it has an impact on our weight and what we eat.  

Different types of microorganisms perform a variety of jobs in your colon, and thus, microbial diversity helps control your metabolism and your body weight.  There are links between the composition of your gut flora and your weight. We know for certain that a diverse gut microbiome is beneficial for your health. The gut flora of people with overweight and obesity show different patterns compared to those of normal weight – the most striking pattern being one of less diversity.  In fact, lower diversity has been observed in people with obesity, type 2 diabetes, arterial stiffness, eczema, inflammatory bowel disease and many other health issues. 

The science behind this is really fascinating – and really complex.  Way more complex than I can get into here, but think about this.  In medicine, we study rodents a lot.  Rats and mice are actually eerily similar to humans in terms of genetics and responses.  When we take feces out of the colon of a rat with obesity and put it into the colon of a rat without obesity (called a fecal transplant), the rat that receives the transplant starts gaining weight.  When we transplant feces from a lean rat into a rat with obesity, the transplant recipient starts losing weight – without any change in their feeding environment whatsoever.  

Human fecal transplants at this time are pretty rare and are typically reserved for patients with severe colon infections.  However, because of the animal data, clinical trials are underway right now to evaluate the use of fecal transplants for all kinds of health conditions. Early results have shown that transplanting feces from a lean human donor into one with metabolic syndrome results in a significant improvement in insulin sensitivity.  Studies assessing the effects on weight have been mixed and rather unimpressive, meaning we have a way to go before fecal transplants potentially go mainstream.  Thank goodness, because transplanting feces is not without risk – just like transfusing blood, there are a whole host of things that have to be evaluated and considered before it can be classified as a potentially safe thing to do.

How can this microbiome have such power over our health?  The human genetic code – the information that makes us individuals – contains about 23,000 genes.  This microbiome encodes over three million genes, producing thousands of metabolites – which actually replace many of the functions of the host (us).  Pretty amazing.  But here’s the really interesting part – and the part that is relevant to what we are doing here.  Although a small percentage of our gut microbiome seems to be genetic, the majority of it is determined by what we eat or don’t eat.  

Fermented foods contain a lot of beneficial gut flora.  These are foods like sauerkraut, kefer, kimchi, and kombucha.  Sadly, you don’t see these a lot within the traditional American diet but most are super easy to obtain.  When we eat these foods, we are actually eating healthy live bacteria that will take up residence in our gut.  We call these healthy bacteria probiotics.  

Probiotics need to be fed.   If we starve them, not surprisingly, they will die off.  Probiotics feed on prebiotics – which are certain carbohydrates that your body can’t digest.  Prebiotics are found in things like vegetables, fruits, beans and legumes and a few other random foods.  They are different from fiber but often go hand in hand – existing in most of the same foods.  This is why vegetables are so good for us.  Yes, they provide us with vitamins and minerals, but their primary benefit is feeding our gut bacteria.  Eating lots of vegetables, especially a wide variety of them containing different colors is the fastest way to improve your gut microbiome. 

Just like we can improve our gut microbiome with food, we can also destroy it.  Eating a lot of sugar and/or artificial sweeteners has been shown to decrease the diversity in our colon.  In fact, artificial sweeteners are increasingly being shown to disrupt the balance and diversity of the gut flora. Food additives, such as emulsifiers found in highly processed foods, have also been shown to affect the gut microbiota – and not for the better. 

Disruption of the gut microbiome can also result from other factors.  Antibiotics have done an amazing job of decreasing premature death from infectious diseases.  The importance of this category of drugs cannot be ignored.  However, antibiotics are designed to enter the body and destroy specific types of bacteria – but in the process, they often destroy a lot of innocent bystander bacteria in the gut as well.  Antibiotics disrupt the microbial communities in our gut – and can promote weight gain.  The link between antibiotics and weight gain isn’t really a secret – industrial agriculture has known for decades that low doses of antibiotics causes animals designed for meat consumption to gain weight faster.  Psychological stress, environmental stress and sleep deprivation all negatively affect the gut flora as well.  

Thankfully, we can look at this list and easily figure out ways to improve our gut microbiota.  Eating a whole food diet rich in plants is the fastest, easiest way to improve our gut flora (and is a lot less creepy than signing up for a clinical trial involving repetitive fecal transplants!).  Avoiding a lot of sugar and artificial sweeteners can also make for a quick improvement.  Getting good sleep, avoiding unnecessary stress, and even exercising has been shown to improve gut flora.  In other words, treating your body well – giving it what it is designed to eat and taking care of your brain and health, translates to better health overall.  

There is no such thing as a weight-loss gut bacteria supplement, so please don’t rush out and buy one.  Don’t try to find a back alley fecal transplant either.  Don’t get suckered into marketing or hype.  Scientists in every country are trying desperately to find treatments for obesity.  If they can find something that works, they will be famous – and will be immortalized in science history as having done something amazing.  The cost of doing these solid, scientific studies is very high, but the company that finds a solution stands to make a veritable fortune – so trust me, if they find something amazing, it will get thrown out there.  At first, it will be owned by one pharma company or another – it won’t be distributed through a direct sales company or on the internet, so don’t let marketing tell you what you want to hear! 

As always, if you need more help, you know where to find me!

Courtney Younglove, M.D.

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