8 Simple Ways to Improve Your Gut Health
Research suggests that everything from obesity, autoimmune diseases, and cardiovascular disease, to skin issues, mental disorders, and allergies can be traced back to an unhealthy gut or "dysbiosis," meaning the ecosystem of microorganisms living in the gut is out of balance. After all, it has been estimated that only 1% of our genes are human--around 99% are actually bacterial genes! If we have more bacteria cells on and in our bodies than human cells, those little bugs must serve a very important role!
So, what is the gut microbiome and why should you be so concerned about it?
Your gut houses an ecosystem of bacteria and other microbes, referred to as the "gut microbiome." Some of these microbes are thought to be especially beneficial for our overall health, or "probiotics," because they keep the bad bacteria in check, produce vitamins for us such as vitamins K and B12, metabolize bile acids, detoxify chemicals, break down indigestible components of food like fiber, and produce byproducts called short-chain fatty acids which are beneficial to our health.
Overtime, with the advent of antibiotics, antiseptics, and modern agricultural practices, (not to mention an obsession with cleanliness and spending more time indoors), the diversity of the species of bacteria that live in our gastrointestinal tracts has decreased dramatically as we limit our bacterial exposure and kill off existing microbes. We are eating a narrower variety of foods (many of which have become processed and homogenized), and antibiotics are often overprescribed. Our food supply is also a source of antibiotic residues, particularly if you are eating animal products from conventional, commercial sources. Cows along with other farm animals are fed antibiotics as both a prophylactic measure and to fatten them up because farmers discovered early on that when you wipe out the gut bacteria of a cow, they start to gain weight rapidly as a result of dysbiosis. This may be great from an economic standpoint, but think about how abuse of those antibiotics can affect you and your weight too!
We all have a distinct mix of gut microbes which is entirely unique to us, just like our fingerprint--no two gut microbiomes are the same. In fact, studies show that when you transplant gut bacteria from an obese mouse into the gut of a thin mouse, the thin mouse becomes obese, and vice versa, even when both groups of mice are eating the exact same food in the same quantities. This suggests that the balance of bacteria in our gut can drastically impact how much energy we extract from our food and therefore our weight.
Our gut is also home to around 70% of the cells that make up our immune system which is why immune-related health issues are often linked to an out-of-balance gut, with insufficient microbial diversity.
I have pinpointed 8 things that anyone can do to up their gut health game whether you have a condition that stems from an unhealthy gut microbiome, or you are looking to improve your overall health!
1. Increase your total fiber intake
Fiber is food for our gut bacteria. In order to keep the good bacteria happy, we have to feed them a variety of fiber-containing foods. It has been estimated that our Paleolithic ancestors consumed upwards of 100 grams of fiber per day from a variety of plants, yet the average American only consumes around 15-18 grams of fiber per day. It's no wonder that we have all sorts of health issues today that were fairly uncommon up until relatively recently (think allergies and autoimmune diseases...our great grandparents had far fewer incidences of these conditions!). While I wouldn't necessarily recommend that anyone consume 100 grams of fiber each day, especially if you are used to consuming much less, consuming at least the recommended dietary allowance (RDA) of 25-38 grams per day is a good place to start. Keep in mind that the RDA is the minimum amount of fiber we should be consuming daily. I would argue that a fiber intake conducive to optimal health is likely a bit higher. Diets that contain sufficient fiber are naturally predominantly plant-based and rich in some of the healthiest foods that you can consume. Think fruits and vegetables, beans/legumes, whole grains, and nuts/seeds.
2. Up your fermentable, soluble fiber intake
There are many different types of fiber, but for simplicity's sake, let's break it down into two categories: fermentable fiber and non-fermentable fiber. Both types of fiber are important, but fermentable fiber is particularly important for the good bacteria in your gut. This type of fiber passes through your upper GI tract undigested, and eventually ends up in the colon where it serves as food for the bacteria in your gut and is "fermented" by them. Once fed, these fiber-fermenting bacteria produce beneficial short-chain fatty acids (SCFAs) as byproducts. SCFAs nourish our colon cells, suppress inflammation, inhibit the growth of bad bacteria, help control appetite and metabolism, and can even help us to better absorb certain minerals from our food like calcium. Among one of their many benefits is their ability to prevent the conversion of primary bile acids to harmful secondary bile acids in the colon, which acidify the colon and can damage its lining. Overtime, this chronic exposure to secondary bile acids may cause inflammation and even lead to colon cancer. By eating plenty of fermentable fiber sources, we can majorly reduce this conversion of secondary bile acids and protect our colons! SCFAs also promote cell differentiation and apoptosis. Cell differentiation means that the SCFAs help cells to become specialized. For example, they help baby colon cells realize that they are, in fact colon cells and should produce mucus, survive in a slightly acidic environment, etc. Well-differentiated cells are less likely to develop into cancer cells, too. Apoptosis is referred to as "programmed cell death." While this may sound scary, it's actually a very good thing. Healthy cells are designed to die after a certain amount of time rather than hanging on and multiplying past their prime, which can lead to uncontrolled cell growth and possibly cancer.
There are different types of fermentable fibers including beta-glucans found in oats, barley, and mushrooms, pectins found in fruits, oligofructose found in onions, garlic, chicory, Jerusalem artichoke, and more, inulin found in vegetables like asparagus as well as in bananas (especially green bananas), psyllium found in the psyllium plant, and fructo-oligosaccharides found in beans, legumes, whole grains, and some vegetables and fruits.
3. Include insoluble fiber sources
Soluble fiber, as its name suggests, dissolves in water and soluble fiber sources are generally more fermentable (or digestible) by gut bacteria. Insoluble fiber is the roughage that is found in the bran, stems, leaves, and skins of fruits, vegetables, legumes, and grains. Some types of insoluble fiber are fermentable (meaning they serve as food for gut bacteria), but many varieties are not. These non-fermentable fiber sources are still important because they maintain the muscle tone of our intestines and "create bulk" to promote proper elimination. Insoluble fiber creates resistance as it pushes against the intestinal walls on its way out, keeping our intestines in good shape so that they can continue to contract and push food through regularly and forcefully. Without enough insoluble fiber in our diets, we can develop diverticulosis, a condition that results from a weakening of the walls of the large intestine, causing pockets to form within the walls, trapping food which can lead to inflammation and infection (diverticulitis) --no fun! Most plant-based foods contain a mixture of insoluble and soluble fiber, but foods particularly high in insoluble fiber are leafy greens (especially kale--think fibrous stems), celery (the string is all insoluble fiber), the bran portion of whole grains, skins of fruits like apples, and skins of vegetables like cucumbers.
4. Increase the diversity of plants that you eat
The greater the diversity of bacteria species in our gut, the healthier we are! While there are still many unknowns when it comes to which strain of bacteria does what, we do know that each strain has a specific role in the ecosystem that is our gut microbiome and when we have little variety of bacteria in our gut, the ecosystem is unable to optimally support our health. Since each plant contains a different mixture of different types of fiber, it makes sense that eating a wider array of plants would promote a wider array of gut bacteria to grow and thrive. Think of it as providing your healthy gut bacteria with a buffet of different food options. They like variety!
There is a small tribe of hunter-gatherers left in Tanzania called the Hadza, who have been able to segregate themselves from modern civilization entirely. They exclusively hunt and forage for their food, and their diet contains about 100-150 grams of fiber each day. They have extremely low incidences of autoimmune disease, allergies, diabetes, or cardiovascular disease. Studies conducted on the microbiomes of the Hadza show that they have a massively diverse variety of gut bacteria, many species of which are nonexistent in the GI tracts of people living in industrialized countries, where a western diet is consumed (accompanied by a western lifestyle). This can be partially attributed to the fact that they consume a wide variety of plants that they forage for, all of which are high in fiber. There is good news for us, though! The studies done on the Hadza also demonstrated that their gut bacteria actually shift and adapt based on the season and what they are eating. This suggests that our gut microbiomes are dynamic, constantly evolving and responding to what we feed them, therefore there is hope that we can increase the diversity of our gut bacteria--we just have to feed them properly. Research demonstrates that aiming to consume at least 30 different types of plant foods each week is ideal for optimizing gut microbiome diversity and health, but increasing the variety of plants you eat even by two or three each week, is a step in the right direction! Check out my [incomplete] list of fermentable fiber-rich foods and probiotic-rich fermented foods below, to add to your grocery list and expand your repertoire.
5. Incorporate fermented foods into your diet
Fermented foods have been around for ages and many even serve as staples for some cultures like kimchi in Korea, miso in Japan, and sauerkraut in Germany. The process of fermentation is carried out by microorganisms including bacterial strains that are beneficial to our microbiomes, so when you consume these fermented foods, you are also ingesting the bacteria that helped to ferment that food, subsequently expanding your microbiome. Although the journey from our fork down to our colon is treacherous for any microorganism as they must survive stomach acid, bile, enzymes, and more, there have been studies conducted which demonstrated that when consumed in moderate quantities, bacteria from fermented dairy products and kimchi is able to survive the journey and does in fact end up adhering to colon cells--I won't get into how they tested this, but I'm sure you get the idea. So spoon some sauerkraut onto your salad, have some tempeh, whip up a miso-based salad dressing or soup, have a yogurt, and incorporate kimchi into your day! Pairing these fermented foods with fermentable fiber sources such as beans and legumes, garlic, onions, oats, barley, and fruits makes the probiotic action of the fermented foods even more powerful since the probiotic bacteria will then have plenty of food to thrive off of once they get to your colon.
6. Extend your overnight fast
Up until relatively recently, humans ate intermittently rather than continuously throughout the day. When we graze all day and eat late into the night right before bed, we don't give our GI tract a break or a chance to reset. Our GI tract is a pretty amazing machine and when we are in a fasted state (i.e. overnight), our intestines release motilin, a hormone that causes muscle contractions in the small intestine which allow undigested food and bacteria from that day of eating to be pushed down into the colon where it can then be eliminated. If your body is working overnight to break down a big meal that you had before you went to bed, then motilin is not released and this built-in cleansing process cannot take place. This can lead to something called SIBO, also known as small intestinal bacteria overgrowth which can cause bloating, abdominal distention, and abdominal pain among other unpleasant symptoms. There is also some new research which suggests that extending your overnight fast favors good gut bacteria and may elicit an anti-inflammatory response. Giving your body a break from eating for at least 12 hours overnight is a great window to aim for to ensure that your intestines can reset and to potentially encourage those good gut bacteria. That said, always consult with your physician or registered dietitian first, especially if you have a medical condition affecting blood sugar such as diabetes.
7. Don't fear dirt! Try to get outside in nature every day (if possible) and ease up on the hand sanitizer
The more you *safely* expose yourself to bacteria, the more opportunity you give yourself to develop a diverse microbiome. If we sit inside a sterile environment all day, we aren't exactly encouraging the introduction of more beneficial bacterial strains in our bodies. Hand sanitizer, antibacterial soaps, and cleaning products are no help either. While it is important to take full precautions when handling anything that may contain harmful bacteria such as raw meat or after using the bathroom (e. coli and salmonella are not the bacterial species I had in mind...) and if you are immunocompromised, when it comes to daily activities, Americans tend to be overly sterile to the point where we are stunting our microbiomes and immune systems. Getting back to the Hadza tribe, another contributor to why they have such diverse microbiomes is the fact that they expose themselves to lots and lots of bacteria by eating a variety of foods, spending the majority of their time outside, and not making chemical sanitizers, pesticides, detergents, or antibiotics a part of their daily lives. Having a pet that spends a portion of their time outdoors can also help to diversify your microbiome, especially if you pet them often which I'm sure they will appreciate too!
8. Only take antibiotics when absolutely necessary
Don't get me wrong, I'm not "anti-antibiotic." Once discovered, antibiotics drastically increased the human life expectancy and there is a time and place when/where they are absolutely necessary. That being said, antibiotics have been overprescribed and are not as benign as we once thought. In fact, taking Cipro, a common antibiotic for just 5 days wipes out 35% of our gut bacteria, and it can take 1-2 years to restore the gut bacteria after that. Some species, however, may be lost altogether. If you must take antibiotics, though, don't panic! Once your course is over, just be sure to increase your fermented food and fermentable fiber intake, spend lots of time outdoors, consider experimenting with extending your overnight fast (first consult your physician or registered dietitian), and get adventurous with trying new fruits, veggies, whole grains, and legumes!
But what about taking a probiotic supplement?
Microbiome research is still a young field, and we have not yet been able to identify exactly what each strain of bacteria in our microbiomes does and how they interact with the yeasts, fungi, protozoa, and other microbes inhabiting our colons. We also do not yet know what the ideal "healthy” gut microbiome should look like--which strains and in what ratios promote optimal health. For these reasons, I do not believe that generic probiotic supplements are necessary or even a good idea for the average person to take unless a specific formulation is prescribed to you for a specific reason by your gastroenterologist, or recommended by a registered dietitian specializing in gastrointestinal health. If you have been on antibiotics for a prolonged period or have a gastrointestinal illness, you may also benefit from a probiotic, but it is not as simple as purchasing a generic multivitamin at your local CVS. In the near future, the science may be advanced enough to take a culture of an individual's gut microbiome, compare it to that of a reference healthy microbiome, and then prescribe probiotic supplements tailored specifically to that individual, supplementing with the strains that they are missing. Until then, ingesting random strains of bacteria that are thought to be good for us may not be helpful. In addition, if you are taking a probiotic supplement but not eating properly, all of those probiotic bacteria that you ingested won't have sufficient nourishment once they get to your colon and won't hang out for very long. Probiotic supplements are also notoriously expensive. For now, the easiest and most efficacious way to impact on our gut microbiome is through diet.
Some gut health superheros to incorporate into your diet:
Apple
Asparagus
Barley
Beans
Berries
Buckwheat
Cabbage
Chia seeds
Fennel
Flax seeds
Garlic
Jerusalem Artichoke
Jicama
Kimchi
Leeks
Lentils
Miso
Mushrooms
Natto
Oats
Onions
Pear
Pickles
Radishes
Sauerkraut
Seaweed
Stone fruits (peaches, plums, cherries, apricots, nectarines)
Tempeh
Tomatoes
Unripe banana
Yogurt/Kefir