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Good news! Even though we just took a virtual field trip around the world to the Blue Zones, we are not going to take a field trip into your intestines, where your gut microbiome is located. You’re welcome.
After all, deep inside your gut microbiome is probably not a very pleasant place to be...unless you are one of the trillions of bacterial cells residing there. Most of us don’t spend a lot of time thinking about our gut region, but what goes on in this entirely unsexy part of your body is much more important than many people realize. How many bacteria live there? According to one estimate I read, if you took all of your gut bacteria and lined them up, one by one, the line would stretch from the earth to the moon. This population includes hundreds of different species, and it varies dramatically from person to person. Your specific gut microbiome is as unique as your fingerprint.
Based on everything I’ve been reading about the importance of the gut as it relates to our overall health, I don’t think that it’s a stretch to say that if your gut microbiome is unhealthy, then YOU are unhealthy. In fact, if your gut is unhealthy, you are more likely to be overweight, and you are also likely to have a hard time losing weight, no matter how hard you try.
I remember first hearing about the link between your gut microbiome and your weight years ago, when I was still overweight myself. I can’t remember how I first heard about it, but the story sticks in my head.
According to what I remember, whatever article I read that day described how scientists took samples of the gut bacteria from obese mice and transplanted these samples into lean mice. This is known as a fecal transplant. With NO change in diet, the lean mice became obese themselves.
What?!?!?
Prior to that moment, I believed that losing weight was completely in our conscious control. I believed that if we had enough willpower and followed the right type of diet, we could and would lose weight. Isn’t that what we all have been told? “Eat less, move more.” If that isn’t working, then it’s because you are lazy, or you are a glutton, or, even worse, you are a lazy glutton. Suddenly, though, I had a new paradigm to consider. Was there something “wrong” with my gut microbiome that made it so hard for me to lose weight? Was it possible that it wasn’t my fault, after all?
The problem was that even after reading about those mice, I still didn’t know what to do about it. I remember going down to the health food store and wandering around the probiotic section. I knew that probiotics were supposed to improve gut health, but I had no idea where to begin, or which type to try. I bought some really expensive probiotics and started taking them. As with most things, I soon lost interest when I couldn’t perceive any outward (or inward) changes. I mentally filed away the mouse study, hoping that one day we would know more about how to change our own gut microbiomes.
Well, that day is fast approaching, and it is completely thrilling.
Over the past decade or so, scientists have made some amazing discoveries about what actually lives in our gut. As new technologies have been developed, researchers are able to use genomic sequencing to identify the various bacterial species living deep within us. They are finding incredible correlations between specific species living in our gut and our overall health.
The story about fecal transplants in mice remained buried in my memory, until I heard another amazing story about the effect of the gut microbiome on weight. In 2015, scientists reported a case study about weight gain after a fecal transplant, this time in humans. Here is a link to the case study:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4438885/
According to physicians, a woman received a fecal transplant as a treatment for an infection called Clostridium difficile. The official term for this procedure is a “Fecal Microbiota Transplant,” or FMT. While it seems cringe-worthy, doctors take a sample from a stool donor and transfer it into the patient. The woman in this specific case selected her 16-year-old daughter as the donor. At the time of the FMT, the woman weighed 136 pounds, and her daughter weighed about 140 pounds.
Here’s where the story gets interesting. 16 months later, at a follow up appointment, the woman had gained 34 pounds and was now classified as obese, with a BMI of 33. Prior to that, she never had any trouble with her weight. Suddenly, though, as hard as she tried, she was unable to lose weight, and kept steadily gaining. 36 months later, her weight was up even higher, leaving her with a BMI of 34.5. The odd part of the story is that the daughter also began to gain weight after the FMT, and ended up reaching 170 pounds herself.
Scientists hypothesized that since neither was obese prior to the FMT, either the procedure somehow triggered changes that led both women to gain weight, or prior to the transplant the daughter had an unhealthy gut microbiome that hadn’t yet begun to affect her weight, and this only came to light after the procedure. As a result of this case, this specific physician’s group created a policy to only use non-obese donors for any future FMTs. The funniest part of this whole case study is in the last paragraph of the paper, where the author discusses the use of “professional” stool donors for future procedures. Can you imagine that conversation at a cocktail party?
“So, Claude. What do you do for a living?”
“I’m a professional stool donor.”
Claude would probably have trouble finding dates.
All jokes aside, the idea that we may be at the mercy of what resides in our gut is both fascinating and somewhat liberating, because if we can figure out how to correct imbalances in our gut, we should be able to affect our own health in many ways.
For an introduction into this fascinating world, I highly recommend that you read a comprehensive review article that appeared in “Integrative Medicine.” This article is called Part 1: The Human Gut Microbiome in Health and Disease. Here is a link to the article, which you can read in its entirety:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4566439/pdf/17-22.pdf
As we read about a healthy gut in this article, we learn that among the many types of bacteria present, there are 2 main phyla, or categories: Bacteroidetes and Firmicutes. The ratio of these 2 different types of bacteria seems to be different in the gut of lean creatures when compared to obese creatures, and obese mice (and humans) tend to have a higher proportion of Firmicutes, while lean mice (and humans) tend to have more Bacteroidetes. Yes, much of the research continues to be done using mice, as in the first study I remember hearing about, but we find many similarities as we move into human studies.
According to what we are learning, our gut microbiome affects both our metabolism and our immune system. In addition, scientists have discovered something called the gut-brain axis that shows that our gut is somewhat of a “second brain.” Apparently, there is constant 2-way communication between our gut and our brain, and our behavior can even be affected by what resides in our gut. This gives a new meaning to the phrase “gut instinct”, doesn’t it?
In fact, scientists are finding that our gut microbiomes actually seem to somehow influence what foods we crave. An unhealthy gut microbiome has been linked to an increased preference for highly processed foods, and a more diverse and healthy gut microbiome appears to direct us to eat “healthier” foods. That’s pretty remarkable, and it explains a lot.
So, how do our gut microbiomes end up in the states they are in currently, as either healthy or unhealthy? As it turns out, it’s literally taken our whole lives to build whatever gut microbiome we currently have in place.
Let’s go all the way back to the beginning. At the moment of our birth, microbial colonization begins. Researchers are finding that our method of birth actually has impact upon our microbiome: babies who are born vaginally have a more diverse population than those who are born by C-section. Throughout the first year of life, the microbiome continues to develop, and depends on many factors: whether you are breast or bottle fed, whether you need antibiotics, and when you begin solid food. Expect to hear more about this in coming years, because the more we learn about the microbiome, the more we realize that we can make a difference in our children’s lives based on decisions we make starting at day one. In fact, just the other day, I saw a book targeted to pregnant women, all about developing your baby’s gut microbiome. (One thing to note: it is at this point that some women begin to have guilt over having C-sections or bottle feeding their babies. STOP THIS GUILT, mothers, and understand that some factors are out of our control. If you had a C-section or bottle fed your baby, I am sure you did what you needed to do at that moment to keep your baby alive, which makes you a very good mother.)
Throughout our lives, our gut microbiomes continue to develop in response to what’s around us and what we eat. It turns out that what we eat is very important in developing a healthy gut microbiome. What are the very worst things we can eat? You’re probably not surprised to find that it’s the modern-day Western diet, high in overly-processed and refined foods. Preservatives. Artificial sweeteners. Chemicals. All of these are implicated in an unhealthy gut microbiome. Oops. Apparently, it is our fault, after all. The unhealthy foods we chose to eat over the years weren’t just “empty calories” as we were led to believe. No, it’s much worse than that. These food choices were actually encouraging the growth of unhealthy bacterial species in our gut, at the expense of the beneficial ones.
When we feed our bodies foods that are both devoid of nutrients and highly processed, we end up with a microbiome that is out of balance. The result is inflammation, metabolic syndrome, and disease. Yes, all of these conditions can be linked back to an unhealthy gut. Here is an article that explains this further. It is called Impact of the Gut Microbiota on Inflammation, Obesity, and Metabolic Disease, and it can be found at this link:
So, we see that when our gut is out of balance, we end up with inflammation, metabolic disorders, excess fat accumulation, and insulin resistance. Now we can understand one reason why the Western diet is especially good at promoting obesity: it is specifically related to establishment of an unhealthy gut profile.
Here is something else that may absolutely shock you. When you have an unhealthy gut microbiome, your body is better at taking the energy from your food and storing it as fat. Yep, you read that correctly. You store MORE FAT from LESS FOOD than someone with a healthy gut microbiome.
If you always felt like you gained weight eating less food than the people around you, you were probably right. This is another reason why the calorie-model of weight loss fails. If you are able to extract more energy from your food, thanks to your gut microbiome, the calorie formulas aren’t going to work very well for you. After “failing” at another calorie-restricted diet, it is as this point when many overweight people are accused of lying about what they are eating. Based on the calories in/calories out model, they should clearly be losing weight. But because of what is happening in their gut, they have different results.
Here is an example of that principle in action. Scientists have found that a specific type of “germ-free” mice typically eat 29% more calories than normal mice, yet they have 40% less body fat. These germ-free mice are also protected against insulin resistance. However, when a FMT is performed, transplanting microbes from normal mice, these germ-free mice see a 57% increase in body fat and a dramatic increase in insulin resistance, even when their diets are not changed at all.
According to this particular research, scientists have found that there are several ways that the gut microbiome affects energy balance and contributes to obesity. When we have the gut microbiome profiles that are correlated to obesity, we find that:
After learning all of this, we see that it is incredibly important to make choices that lead to the right kind of gut microbiome. I have good news for you! We can influence our guts positively in two ways: through fasting and by making certain food choices.
It’s true! Fasting has been linked to beneficial changes in our gut microbiomes. One fascinating study was conducted in 2014, and results were reported in an article called Increased Gut Microbiota Diversity and Abundance of Faecalibacterium Prausnitzii and Akkermansia After Fasting: A Pilot Study. Here is a link to the study:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4452615/pdf/508_2015_Article_755.pdf
In this study, scientists worked with thirteen overweight people to see what would happen to their gut microbiomes when they put them on a fasting regimen followed by probiotic supplementation. (Okay, 13 people is a very small sample size. Keep that in mind. Even so, the research is interesting.) They spent one week on the fasting protocol, and then spent six weeks ingesting a specific probiotic formula. Fecal samples were taken before the study began, during the fasting portion of the protocol, and after the probiotic treatment.
The scientists found that as a result of the fasting protocol and subsequent probiotic treatment, there was an increase in microbial diversity, with a specific increase in Akkermansia and Bifidobacteria. Both of those species are associated with a lean and healthy gut profile. Akkermansia is specifically associated with fasting, as it is a species that lives on the mucus in your gut lining. This is just another reason to feel good about your decision to adopt an intermittent fasting lifestyle!
So: what do our gut microbiomes like to eat? Besides Akkermansia, who thrive when we are fasting, there are other species who need specific foods that they can only get from what we send down to them. When we feed the good guys in our guts, they are able to crowd out the bad guys over time. The types of foods that best feed our good guys can be called “prebiotics.” Note that this is not a typo. Prebiotics differ from probiotics.
Prebiotics are foods, primarily composed of oligosaccharides or short-chain polysaccharides. One famous prebiotic fiber is inulin, which you may have heard of. While we can supplement our prebiotic intake with certain prebiotic supplements, the most powerful way to feed our gut bacteria is to consume prebiotic foods.
As I already mentioned, a Western diet of highly processed and nutrient-deficient foods is terrible for our gut microbiome. To find out how we should (and shouldn’t) be feeding our microbiome, we can look to a paper called Starving our Microbial Self: The Deleterious Consequences of a Diet Deficient in Microbiota-Accessible Carbohydrates. Here is a link to this paper:
The authors of this paper suggest that we need to ensure a diet high in what they call “microbiota-accessible carbohydrates,” or MACs, in order to have a healthy gut microbiome. MACs are specific carbohydrates that are broken down in the gut by our bacterial good guys. Think about foods high in dietary fiber. Your grandmother was right: we need to eat more fiber.
Here’s something interesting, though. The carbohydrates that best feed MY gut microbiome might be different from the carbohydrates that best feed YOUR gut microbiome. Our genes play a role in this to a degree, as does the specific composition of our unique gut microbiomes.
Overall, though, we know that certain prebiotic foods tend to feed our gut microbiomes well. These include a wide variety of vegetables, fruits, and whole grains. The good news is that if you eat a wide variety of these foods, you are on the right track: diversity is key, and we want to have a lot of variety from day to day. Foods high in something called “resistant starch” are also great for our gut microbiomes. We find resistant starch in foods such as beans, grains, and seeds.
We also find high levels of resistant starch in certain foods that have been cooked and then cooled, such as rice, pasta, or potatoes. What changes when we cook and then cool these starches? Think about a baked potato straight out of the oven for a minute. It’s fluffy and soft. Now, think about what happens to the texture of that potato if you let it completely cool. You’ll never be able to get the fluffy texture back. The potato underwent structural changes as a result of the cooking and cooling process, and for that reason, it is less digestible within our bodies. It is, however, now a great source of resistant starch, and it will make it to our gut, where it will feed our good gut bacteria. In addition to feeding the good guys, these cooked and then cooled resistant starches lead to a smaller increase in both blood glucose levels and insulin after eating them, as compared to when they were first cooked. Time to bring out the cold potato salad recipes!
Besides feeding our gut microbiomes a wide variety of prebiotic foods, we can also increase probiotic foods to promote gut health. We all have heard of yogurt, with its probiotic properties. Fermented foods, such as sauerkraut, kefir, and kimchi, are also great sources of probiotics.
I’m sure by now you are as fascinated as I am by the possibilities the lie within our gut microbiomes. Starting today, you can work to add prebiotic and probiotic foods into your diet. The more variety you include, the better for your diverse gut microbiome. You can also feel good about incorporating an intermittent fasting regimen. In addition, every time you choose a high quality real food over a highly processed food, you can be sure you are making a great choice for your body. Now you understand why it matters so much.
But, what if you think that your gut microbiome is probably in terrible shape? What if you have a suspicion that you are one of those people that needs to make substantial changes in your microbiome? If you have metabolic issues, increased inflammation, and other health conditions, you probably do need to take more drastic steps to change your gut microbiome.
I am not going to tell you how to heal your gut microbiome, because that is beyond the scope of this particular book. Remember, I am a teacher and not a doctor. Hopefully, I have taught you how important a healthy gut microbiome is to your overall health, but you need to consult with physicians (or read their books) to learn how to heal your own microbiome. I do have some recommended reading for you, however. There are already several great books about the gut microbiome, and I’m sure there are more in the works, as we continue to recognize the importance of the gut microbiome to our overall health and wellness.
If you just want to read more about the gut microbiome, I highly recommend The Diet Myth, by Tim Spector. He is the lead scientist with the British Gut Project, and his book is fascinating. The most important takeaway from his book, in my opinion, has to do with avoiding any restrictive diet that limits the variety of foods that we eat. When we follow a restrictive diet, such as one that eliminates an entire group of macronutrients (as in a program that restricts carbohydrates, and particularly the microbiota-accessible carbs), this leads to a further reduction of diversity in our gut. As we have seen, this is NOT a good thing, and while this type of restrictive diet may seem to correct problems in the short-term, the long-term impact may be detrimental to our gut microbiome.
My favorite parts of The Diet Myth are Tim Spector’s personal stories, which are sprinkled throughout the book. He talks candidly about what he eats, and why. When a scientist who researches the gut microbiome tells me what he himself is eating, I make sure to pay attention. He suggests eating a wide variety of foods, heavily skewed towards vegetables, fruits, beans, nuts, and olive oil. He endorses traditional cheeses, and high-quality yogurts (but not the high sugar/low fat variety.) He also cautions against overly processed foods, and recommends eating less meat overall.
Another book that just came out in mid-2017 is The Clever Guts Diet, written by Dr. Michael Mosely. (This is the title of the British version; I believe the American version will have a slightly different title.) This book is a great summary of what scientists have learned about the gut microbiome, and he goes well beyond what I have shared with you in this chapter. Dr. Mosely also has a 2-stage plan for healing your gut microbiome that you may find to be of value.
If you are interested, you can actually have your microbiome analyzed to find out what you are working with. Both The British Gut Project and The American Gut Project have programs that allow you to send in a specimen for them to analyze. I am waiting for my results now, as a matter of fact. I am sure you aren’t surprised to hear that I am participating in this type of analysis. Reading their report should be as exciting as Christmas morning, now that I understand how important our gut microbiome is. When I mailed off my “sample” I was really glad that the lady at the post office didn’t ask me what was in the package. Awkward.
If you believe your gut problems go beyond what you may be able to correct through reading a book and making simple dietary changes, you may need to consult a physician who works with the gut. If you suspect that you have sensitivities to grains, dairy, etc., there are things that you and a doctor can do to point you in the direction of healing. Your overall goal would be to heal any underlying issues so you can reintroduce foods that you would like to eat.
Also, one thing I want to mention. If you are working on gut health at home, it’s important to understand that you don’t want to make too many changes at once. If you completely change your diet by adding in a lot more fiber than you are used to, coupled with a lot of probiotic foods, it may feel like World War III is being fought inside of you. You may feel a lot worse than you did before you started, and you’ll be cursing the day that you ever took any of my advice. So, start slow. Make one change at a time. You’ll be glad you did.
Now that we understand how important it is to feed our gut microbiomes well, let’s see if we can connect this information to what we read in the chapter about the Blue Zones.