Many of our favorite products are built via an assembly line, which is all about production and efficiency. Each person has a role in the assembly line, and then passes off their task to the next person.  Everyone is working towards the same goal, but they don't have much overlap beyond that. If someone is not performing or a part isn’t working, simply just replace it. For years, this is how many of us unconsciously thought about our bodies and how scientists thought of our gut and digestive system. A series of parts that help achieve a collective mission, not something intricately interconnected.  And certainly not something that impacts the way we feel, sleep and think. But in his bestseller The Mind-Gut Connection, Dr. Emeran Mayer argues that thinking of the digestive system like a pre-programmed machine is simply incorrect. "We ate, chewed, and swallowed our food, then our stomach broke it down with mechanical grinding forces assisted by concentrated hydrochloric acid before dumping the homogenized food paste into the small intestine…which disposed of what remained by excreting it.” Eat, process, excrete, repeat. This was an easily grasped concept, but it was too simple. Instead, what science has discovered is that our gut is more like a supercomputer. In this "supercomputer" model, we see that everything is connected and way more complex and intricate than previously thought.  As Chris Stapleton once mused:  "I drink because I'm lonesome, and I'm lonesome 'cause I drink." Both mutually affect the other, and you can't solely point to one as the root cause.  The two-way connection from our gut to our brain works similarly.  Uncovering more about the gut microbiome (more below) has led to breakthrough discoveries in just how much something like anxiety, for instance, is tied to gut health. Mayer writes in his book:  “Every day more and more scientific literature offers evidence that disturbances of brain-gut interaction have implications for a wide array of health issues, from conditions like food sensitivities and functional GI disorders to psychiatric disorders like depression and food addiction…” Since the science is new, that may lead to some natural skepticism. But as Mayer puts it, “the mind-body connection is far from a myth; it is a biological fact, and an essential link to understand when it comes to our whole body health.” As you’ll find with the studies we'll discuss today, there's overwhelming evidence to affirm this truth – that what you eat affects your brain.


Central to understanding the mind-gut connection is the discovery of the microbiome. At first mention, this sounds like a weird concept you'd study in biology class, or the home of an alien species that Millie Bobby Brown is fighting off in Netflix's Stranger Things. But in actuality, the microbiome exists right inside of us. Think of it like a city with trillions of residents scrambling around to do a different job.  Here's how the Harvard describes it: "[It consists of] trillions of microorganisms (also called microbiota or microbes) of thousands of different species. These include not only bacteria but fungi, parasites, and viruses. In a healthy person, these “bugs” coexist peacefully, with the largest numbers found in the small and large intestines but also throughout the body." Yes, packed within your gut is a population of microorganisms a thousand times the size of earth's population. Not every one of these microorganisms is beneficial, but most of the time they live in a balance. Most of the gut bacteria are "good."  However, if that balance is thrown off, due to outside forces (an unhealthy diet, for instance), it can create a harmful environment.  "If there is a disturbance in that balance—brought on by infectious illnesses, certain diets, or the prolonged use of antibiotics or other bacteria-destroying medications—[imbalance] occurs, stopping these normal interactions. As a result, the body may become more susceptible to disease," the Harvard study continued.  These tiny microbes play a vital role in the function of our immune systems, break down toxins, and help incorporate certain vitamins and amino acids. For instance, Bifidobacteria (a "good" gut bacteria) can help prevent tumors.  In modern science, doctors and nutritionists can measure the health of the gut via a stool test, consisting of five markers that are interconnected with the microbiome: maldigestion, inflammation, infection, dysbiosis and metabolite imbalance.  Which goes to say, some of us could pass as healthy via a routine blood test, but a much more comprehensive study like this could reveal a completely different story. As Mayer explains in his book, these methods could even reveal whether we are in a “predisease” state. “Microbiome scientist James Kinross says that "the gut microbiome is the most important scientific discovery for human healthcare in recent decades. We discovered it – or rediscovered it – in the age of genetic sequencing less than 15 years ago," The Guardian reported.


Put simply, science has revealed that the gut microbiome can have a major impact on our feelings and emotions. "The gut can influence our basic emotions, our pain sensitivity, and our social interactions, and even guide many of our decisions – and not just those about our food preferences and meal sizes," Dr. Mayer adds. This may sound at first like your gut microbiome is "controlling" you or robbing your autonomy. However, think of it like the Instagram algorithm. It certainly influences you, but it doesn't force you to watch or partake in the content.  At the present time, scientists have discovered more about how negative emotions affect our gut through research than the effect of positive emotions.  When we are in stress, our brain sends communicative signals to our digestive system, and our stomachs begin contracting and ramping up acid production. This slows the digestion of whatever we had for lunch, as our intestines barely move when we're depressed.  In The Mind-Gut Connection, Mayer tells the story of a patient who couldn't stop vomiting, which was a result of an overactive stress response in the brain. That’s how deep the mind-gut connection goes. As you’ve probably seen, the neurotransmitter serotonin has gotten a lot of media attention in recent years because of its link with depression. Mayer reflects on this, writing: “The drugs most often used to treat depression.. boost the activity of the serotonin-signaling system, which psychiatry had long thought is exclusively located in the brain. However, we know today that 95 percent of serotonin is actually contained in specialized cells in the gut, and these serotonin-containing cells are influenced by what we eat.” This is mind-blowing. Practically speaking, it means that certain diets can LOWER serotonin production. This brings to light the reality that even as we ramp up our serotonin levels through medication, we also may be simultaneously depleting them through what we’re eating. For instance, a diet lacking tryptophan (which helps with serotonin production) can increase the prevalence of depression in at-risk people. Moreover, science has found that many people experience comorbidity, suffering from a mental health disorder (i.e. PTSD, OCD) and a gut disorder (i.e. IBS) at the same time. This isn't a coincidence. To be clear, we're NOT suggesting that neglecting certain food groups would automatically lead to depression or a mental disorder. Or that you should get off your SSRIs immediately and focus on diet. Those are conversations to have with your doctors or therapists.  Rather, this all just simply highlights the role our diet can play in our feelings and mental health. If we're deficient in certain essential food items, it can play out in our emotions.  In a society in which mental illness affects millions of Americans each year, this is incredibly pressing information. What if a better understanding of the gut could lead to better treatments for depression and anxiety, or comorbidities that come with them, like irritable bowel syndrome (IBS), or obsessive compulsive disorder (OCD)? There are of course other factors at play, but this groundbreaking research on our gut could be the key to unlocking issues typically deemed "only in our head."


Going a step further, there’s also been a stream of research studying the link between the gut microbiome and cognitive disorders, like Alzheimer’s, autism spectrum disorder (ASD) and Parkinson’s.  "Emerging research suggests that the human gut microbiota may provide a potential avenue to enhance cognition," says an article published in the research journal Nutrients. It should be noted before diving in that research is relatively new on this topic. And even the researchers in this study admit that though the findings are promising, they warrant further research.  With that in mind, what are some ways that the overall composition of our gut flora (microbiome) could impact the way we think? One area that researchers are particularly fascinated with is the connection between gut composition and autism.  Extensive research through the years has shown that about 75% of people with autism have some kind of gut abnormality or imbalance, such as digestive issues or intolerances.  Sarkis Mazmanian, a researcher at the the California Institute of Technology (#9 in the world for best universities in the world), found that many people with autism have low levels of the bacteria Bacteroides fragilis. In his study done with mice, Mazmanian observed an improvement in behavior and a reduction in anxiety when Bacteroides fragilis was fed to them & incorporated into their gut microbiome. There's still some missing links there, but statistics like three-quarters of autistic people having some kind of gut abnormality is too high a figure to be ignored. Researchers are trying to draw a direct link between gut microbial composition and cognitive status. Research from JAMA Neurology suggests a connection between gut composition and cognitive aging.  That would explain why many have been fascinated with how something like a gut imbalance or lack of diversity could contribute to degenerative diseases like Alzheimer's or Parkinson's.  According to the research, data suggests that "the gut microbiota may be associated with cognitive aging, but must be replicated in larger samples and further researched to identify relevant pathways." If more conclusive evidence is found, the stakes are incredibly high.  The number of Americans projected to be living with Parkinson's by 2050 is 14 million and the number with Alzheimer’s projected at 13 million. The toll on family morale and finances will be astronomical, but there's hope that these diseases are not totally unpreventable.  Lifelong alterations in the gut microbe could play way higher of a factor than previously imagined.  This all underscores a simple point: what we eat matters, both for our physical and cognitive health.


We’ve discussed this extensively elsewhere, but the American diet is destroying our bodies. Since the 1960s, disease has been rising at a meteoric rate in the United States. Many people are suffering from chronic illnesses – 80% of which could have been avoided. In his book, Mayer says that this diet is “profoundly unnatural..one that’s full of sweeteners, emulsifiers, flavorings and colorings, with extra fat, added sugar, and vital gluten, and loaded with calories.” As we’ve learned, this isn’t just terrible for our bodies, but also our minds. In one of our foundational blogs, “The Power of Food, Explained”, we contrast the healthy diet (minimally processed, organic and whole foods) with the more common unnatural, unhealthy diet (ultra processed and tons of additives). It’s a two-sided coin. Food isn’t neutral. Either we can feed it with the good, or feed it with the bad. The mind-gut connection rests on this balance. So what’s the road forward? Some would advocate for a particular diet – the Mediterranean Diet, the Paleo Diet, the Keto Diet, the Carnivore Diet, the Vegan Diet – the list goes on. But we would exercise caution before you plunge in, because you first need to consider your bio individuality. This term was originally coined by Joshua Rosenthal, the founder and director of the Institute for Integrative Nutrition (IIN) in New York City.  He explains, “Bio-individuality means there is not a one-size-fits-all diet, each person is a unique individual with highly individualized nutritional requirements.”  In essence, bio individuality is why one person could claim that going Vegan saved their life, while another person could say the same thing about the Carnivore Diet. This means that any particular diet may or may not work for you. You’re unique. It’s going to be trial and error, and something you need to figure out with time.  Nonetheless, there are some universal principles all of us can use to enhance the mind-gut connection, in a positive way. Here’s just a few.

Avoid Highly Processed, Packaged Foods

No matter what diet or eating regimen you employ, everyone should avoid ultra processed foods. Like yesterday. Ultra processed foods are at the root of health issues. They are filled with harmful additives, some of which are banned in Europe, yet still are allowed on the shelves of grocery stores in the United States. Some foods are so processed that they really shouldn't even be considered "food" anymore. They’re basically a concoction of chemicals that taste good.  To learn more about processed foods, read our full blog here. Beyond just looking at the ingredients list to see what is in the product you’re considering buying, we should also consider how our food is being made, particularly when it comes to livestock.  Industrial farming seeks to maximize output, no matter the cost, leading to situations where the animals we eat are consuming diets not meant for them, thus upping their need for antibiotics.  Their gut microbiome is being hampered, and through consuming these animals, ours will be too.  This is why we should always eat organic, as it will provide long-term benefits to your brain and gut health. Research argues that organic foods are better as they reduce exposure to pesticides, which have been known to be harmful to the gut.  Organic meat always ensures no added hormones, and antibiotics.  Moreover, just because something doesn't have the "USDA Certified Organic" label, doesn't mean it's not organic. Many small-farms that set up booths at farmers' markets don't have the budget to afford the "Organic" sticker, yet still raise their produce and livestock organically. Ask them about their practices as you pass by their station on the street. While it's true that organic food costs more, there’s a reason. That's what real food actually costs. Nonetheless, if budget is a big concern, there are ways to still eat organically on a budget.  Methods like shopping in bulk (Costco actually has a good organic selection), growing your own produce, frequenting farmer's markets, or buying foods that are in-season.  And if none of those are an option, remember the clean fifteen, a list of produce with the least amount of pesticide use. These include vegetables like avocados or sweet corn. On the flip side, also consider the dirty dozen, produce you want to ensure is organic.

Incorporate Fermented Foods & Probiotics

Drinking kombucha (a fizzy fermented tea loaded with probiotics) may seem like a new fad reserved for trendy urbanites, but humans have been reaping the benefits of fermented beverages and foods for centuries. In fact, kombucha is said to have originated as early as 220 B.C. near Ancient China. The biggest perk of fermented foods is that they all contain probiotics, live microorganisms, bacterias, and yeasts that are largely beneficial for your body. Probiotics have benefits from improved digestion to increased immunity.  Naturally fermented foods like kombucha, kimchi, sauerkraut, miso, tempeh, or yogurt, can provide a healthy dose of probiotics.  Moreover, these probiotic-rich, fermented foods aren't super expensive. A 32 oz tub of nonfat Greek yogurt ranges from $3.00-5.00 depending on location, and a 14 pack of Humm Organic Kombucha costs about $28.00 at Costco, which comes out to be a modest $2.33 per bottle.

Eat Smaller Portions

The sheer volume of food we consume is unnatural and has undoubtedly taken a toll on our gut health.  Unnecessarily large portion sizes have contributed massively to the rise of obesity in the United States.  Eating smaller portions more frequently instead of a massive breakfast, lunch, and dinner, can help the stomach to empty more quickly and reduce discomfort related to digestion. It also limits your overall caloric consumption, "keeping the amount in line with your body's metabolic needs and simultaneously [reducing] your fat intake," per Dr. Mayer.  Try switching it up by preparing snacks and smaller meals beforehand. It can be tricky between school, work, meetings, commute, family responsibilities, and extracurricular activities, but try to avoid just eating one massive meal that burdens your digestive tract.

Try Fasting

Going even further, consider periods of fasting (or not consuming anything but water). Research has found that the microbiome's composition shifts and changes after fasting. "There’s a rapid expansion of a particular bacteria (Akkermansia muciniphila) that's associated with positive health markers, like decreased intestinal inflammation and a healthier gut barrier," the article states.  Another 2018 study done on Salmonella typhimurium (a pathogenic bacteria) infected mice found that fasting led to the eradication of this bacteria, as well as colitis. Moreover, in our blog unpacking the science of fasting, we learned of the many studies done that correlated fasting with the improvements of mental health issues. From a physical standpoint, fasting also just gives your gut a break in general.  As we just mentioned, the volume and prevalence of eating is much higher in our food-plentiful society, and our bodies weren't designed to handle the density of food coming in.  Giving the gut time to restore itself, particularly for those with "leaky" guts, is crucial. Leaky guts have a weakened lining, potentially allowing toxins to permeate it. It can lead to uncomfortability, bloating, and food sensitivities. Fasting may sound daunting, but you can ease your way in.  Try skipping a meal or fasting everything but water for just a few hours. Take note of how your gut and overall mental/physical health feels after letting your body rest and reset. Then ramp it up to eight hours and so forth. Here's how Mayer describes the benefits of this "reset": "fasting may also reset the many sensory mechanisms in the gut that are essential for gut-brain communication. Having no fat in the intestine for one or more days may enable vagal nerve endings to regain their sensitivity to appetite-reducing hormones.

Consider the Holistic Self

“We cannot expect that any simple intervention by itself, such as a particular diet, will optimize your gut microbiome, while not paying attention to all the other factors that influence gut microbial function.. the science now says that changing your diet is not enough. You need to modify your lifestyle as well,” Mayer writes. We love this point so much, because it underscores the point that we are holistic beings. As mentioned earlier in the blog, stress can have a profound effect on our gut health. Negative emotional states can throw off the connection between our gut and brain, triggering stress hormones like norepinephrine and serotonin.  Stress can affect digestion and make the intestinal barrier weaker, thus letting in more harmful bacteria and toxins. Restoring a healthy balance to the mind-gut connection involves diet and healthy eating, but it isn’t limited to that. Which goes to say, both for gut and mental health, find activities, people, or purposes that bring you joy and reduce your stress levels.  Whether that's finding a community, exercising, or taking up a hobby that promotes positive feelings, limiting the amount of stress in your life can have massive benefits.  For more on nutrition, click here to visit our Nutrition Hub.


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