How does a healthy gut affect digestive health?

The status of your gut plays a big role not only in how healthy you feel, but also how healthy you are. We all know the uncomfortable feeling of bloating and gas, and many of us have probably had that road trip when we weren’t sure we’d make it to the gas station bathroom in time. But an unhealthy gut can cause even more sinister problems — including system-wide inflammation that promotes a range of diseases from obesity and diabetes to asthma and even certain types of cancers. Fortunately, optimizing gut health is as easy as what you put into your mouth. In this article on gut health and digestion, we take a deep dive into what is a healthy gut, the role microbes play in supporting gut health, and how to avoid and treat gut discomfort and disease.

What is a healthy gut?

A healthy gut can generally be described in two ways: by the presence of certain characteristics and functions and the absence of discomfort and disease. A healthy gut is not only essential for proper digestion and nutrient absorption, but also for helping to protect against a variety of conditions. These are the principal characteristics of a healthy gut:

• Has a tight intestinal barrier and a healthy mucus layer
• Promotes regular bowel movements and a normal amount of gassiness
• Keeps harmful bacteria and viruses in check
• Prevents inflammation and promotes a healthy immune system
• Harbors a healthy gut microbiome — i.e., a stable community that performs particular functions that have a direct beneficial impact on your health and well-being. 

Of the above characteristics, many clinical researchers consider the gut microbiome’s health the most important because it critically impacts so many of the other functions and processes of the gut, which in turn affect the health of other organ systems in your body.

Clinicians actually define a healthy gut as one that isn’t sick. Most professionals agree that a healthy gut, in addition to the characteristics described above, is the absence of:

• Diarrhea
• Bloating
• Mild conditions like irritable bowel syndrome (IBS)
• Small intestinal bacterial overgrowth
• More serious diseases such as Crohn’s and ulcerative colitis (together, these comprise inflammatory bowel disease, or IBD) and celiac disease

Even conditions that aren’t localized to the gut can be a sign of an unhealthy gut ecosystem. Imbalances in the gut microbiome have been associated with a range of diseases, including:

• Obesity
• Metabolic syndrome
• Nonalcoholic steatohepatitis
• Atherosclerosis
• Type 1 diabetes
• Autism
• Allergy
• Asthma

Even a lack of energy and mental clarity can be signs of a problem that originates in or is significantly exacerbated by your gut.

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Essential healthy gut functions

Most of the characteristics of a healthy gut are tightly related, with a limitation in one impacting and/or leading to any one or combination of the others. A healthy gut barrier and lack of inflammation are two of the most important and tightly linked characteristics of a healthy gut, and both are heavily impacted by the microbes that live in our gastrointestinal tracts:

• Inflammation: A healthy gut is one that lacks inflammation. Both food particles and the microbes that live in our gut are “foreign” particles, which means our bodies must have physiological systems in place to avoid inappropriate immune responses to these completely normal and even necessary things. While gut microbes themselves can help the body recognize food particles as harmless, a healthy intestinal barrier is also important to prevent food particles (and bacteria from the microbiome) from crossing into the circulation and causing an immune response. Long-term inflammation in the gut (which can be caused by a number of things including certain medications and infections) can damage this barrier, which further increases inflammation in a vicious circle.
  
  
• Intestinal barrier: As alluded to above, a healthy intestinal barrier is one that doesn’t allow things to cross over into the circulation and cause inflammation. This barrier is maintained by tight junctions, also called TJs, which are composed of over 50 different proteins. Pathogenic bacteria (such as Salmonella), lipopolysaccharide (a bacterial toxin), inflammation, malnutrition, and even certain medications can all compromise TJs. Compromised TJs can lead to something called “leaky gut syndrome,” which, while not a clinically recognized condition, has been associated with the development of more serious conditions such as IBD and celiac disease.

The microbiome plays a critical role not only in supporting a healthy intestinal barrier. but also in preventing inflammation. The relationship is complex and often multi-directional:

• The gut microbiome helps fight pathogenic bacteria, including those that can disrupt TJs, either on their own or via the production of LPS.
  
  
• The gut microbiome produces molecules called short-chain fatty acids (SCFAs), which act as an energy source for intestinal cells and help maintain a tight intestinal barrier.
  
  
• SCFAs also stimulate the production of mucus, which further bolsters the intestinal barrier and traps pathogenic bacteria and viruses. Mucus is also a food source for certain members of the microbiome, including Akkermansia muciniphila, which produce the SCFAs that help promote a tight intestinal barrier and produce more mucus.
  
  
• The gut microbiome contributes to immune homeostasis by supporting and promoting the activity of certain immune system components, including antigen-presenting cells (that help recognize foreign components), neutrophils, and natural killer cells. Gut microbiome-based education of antigen-presenting cells ensures that these cells recognize gut microbes as “self” and don’t mount an immune response against them.

You’ve probably realized by now that inflammation is the common thread connecting all of the concepts we’ve discussed so far. Unfortunately, inflammation in our guts often goes unnoticed until it has become serious enough to become a detriment to our health. 

Inflammation-associated gut conditions and diseases

As alluded to above, inflammation and unbalanced gut microbiomes can contribute to a range of gut conditions. Three of the most common and well recognized yet misunderstood conditions are irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and celiac disease.

• IBS is not a disease, but a syndrome; meaning, its symptoms are mild and long-term damage is limited. Symptoms include stomach cramps, pain, bloating, constipation, and diarrhea — which must last for three months to be considered IBS. Unlike IBD, IBS is never treated with surgery and does not increase a person’s risk for colorectal cancer. It can also be more readily addressed with dietary interventions, which we discuss more below.
  
  
• IBD is actually a group of two diseases: Crohn’s disease (CD) and ulcerative colitis (UC). While CD is intestinal wall inflammation that can impact any part of the digestive tract, from mouth to anus, UC inflammation is restricted to the large bowel (colon and rectum) only. Some symptoms can be similar to those of IBS, but are usually more severe and often accompanied by rectal bleeding and blood in the stool. Both are chronic conditions and can advance to the point that surgery becomes necessary.
  
  
• Contrary to what the popular culture would suggest, most of us do not have celiac disease, which is a chronic autoimmune disorder triggered by the consumption of gluten. Like IBS, celiac can be treated with dietary interventions.

Several research studies have connected microbiome imbalances (called dysbiosis) with IBS, IBD, and celiac; all three are sometimes treated with probiotics (live microorganisms that confer a beneficial effect when consumed), with varying degrees of success. But while a connection between these conditions and gut microbes is clear, the complex mechanisms underlying such connections still aren’t fully understood. Additionally, IBS, IBD, and celiac all have genetic components that predispose an individual to developing them under certain conditions — such as a dysbiotic microbiome; thus, the microbiome is an important contributing factor, but not the only one.

How to support a healthy gut

Supporting a healthy gut involves managing what you, as an individual with the guidance of your healthcare provider, can manage. That is, family history and genetics are variables you cannot do much about. However, managing your lifestyle is within your reach. Stress, smoking, certain medications, and obesity can all negatively impact your gut barrier and contribute to gut inflammation. As or more significantly, what you eat (as much as how much you eat) can affect your gut — and, by consequence, your overall — health.  

The role of prebiotic fiber in gut health

Foods high in fiber are very important for the support of a healthy gut and healthy gut microbiome. As we discussed above, many of the anti-inflammatory and gut barrier-strengthening effects of the gut microbiome are due to SCFAs. SCFAs are produced by gut bacteria when they break down fiber — carbohydrates that cannot be digested by our own cells. Several research studies have linked increased fiber consumption with healthy TJs, prevention of leaky gut syndrome, and production of intestinal mucus. In contrast, high-fat diets low in fiber (i.e, the typical Western diet) are associated with compromised gut barrier integrity and increased inflammation.

Fiber on its own also supports the key characteristics of a healthy gut:

• Fiber helps increase the size and weight of stool while softening it, making stool easier to pass and decreasing your chances of constipation. Regular bowel movements help lower the risk of (and aid in symptom relief from) certain gastrointestinal diseases and hemorrhoids, and are also linked to a decrease in colorectal cancer. 
• Prebiotic fibers, such as galactomannan (a fiber found in locust bean gum, fenugreek, and alfalfa) and inulin fiber (found in fruits and vegetables like bananas, onions, and asparagus), have also been shown to delay gastric emptying, which in turn promotes satiety and may therefore aid in weight management.
  
• Fiber intake, by allowing for better digestion, also promotes improved nutrient bioavailability/uptake. 

But not all fiber is created equal, and consuming more fiber isn’t always advised for people who already suffer from particular gut conditions. In fact, a low-FODMAPs diet is often prescribed to manage IBS symptoms, and has been shown to reduce symptoms in up to 86% of people with both IBS and small intestine bacterial overgrowth (SIBO). The FODMAPs diet eliminates “Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols,” which are fermentable short-chain polysaccharides (i.e., fiber). When the bacteria in the colon ferment these dietary components, gas is produced as a byproduct, which can exacerbate the bloating and abdominal discomfort associated with IBS.

It’s also important to consider, before consuming more fiber, the differences between insoluble fibers and soluble fibers and their impact on gut health. Insoluble fibers, which cannot be digested by humans or bacteria, typically only serve to bulk the stool and facilitate bowel movements. (However, some fibers, including wheat dextrin and insoluble wheat bran particles, can actually cause constipation.) Soluble fibers, which dissolve in water, don’t provide the same laxative effect that insoluble fibers do, but many of them are considered prebiotics: dietary fibers that promote the growth and activity of beneficial bacteria (including SCFA-producing microbes) in the intestinal tract. 

Eden’s 3:1 synbiotic contains several prebiotics, all with scientifically proven anti-inflammatory and gut health-promoting properties:

• Resistant potato starch promotes the growth and activity of SCFA-producing gut microbes.
• Locust bean gum is anti-inflammatory, increases TJs, and promotes the growth of beneficial bacteria in the gut.
• Guar gum promotes SCFA production by gut microbes.
• Oat bran promotes the growth of probiotic species (see below) in the gut.
• Barley beta glucan also promotes the growth of probiotic species in the gut.

The role of probiotics in gut health and disease

Given the role of the gut microbiome in supporting intestinal health, it’s not surprising that grocery stores contain an abundance of probiotics supplements all claiming to be the best one for your gut. But buyer beware — not all probiotics are created equal and most of them haven’t been scientifically proven to support an already healthy gut. Certain probiotic species have, however, proven to be particularly effective at treating gut diseases:

• Bacillus coagulans and Lactobacillus paracasei are two probiotic species, both included in the Eden’s 3:1 synbiotic, that have been shown to reduce symptoms of IBS.
  
  
• Some probiotics, including VSL-3 (a mixture of 8  probiotic strains) and Saccharomyces boulardii (a yeast), have shown promise for relieving symptoms (especially diarrhea) of IBD.

Probiotics are also effective for restoring microbiomes damaged by medications such as antibiotics, which in turn is associated with reduced inflammation and improved overall gut health.

Probiotics should never be consumed by immunocompromised individuals, and have also been shown to worsen the symptoms of SIBO. Only take a probiotic supplement under the direction of your healthcare provider.

The role of polyphenols in gut health

There is increasing evidence that nutrients other than fermentable fiber affect the gut microbial composition. Micronutrients and other dietary components consumed in small quantities — such as vitamins, minerals, specific fatty acids and phytochemicals (or phytonutrients) — may also elicit changes in the microbiome. 

Polyphenols, a subset of  phytonutrients (natural chemicals found in plants, that help protect plants from germs, fungi, bugs, and other threats), are receiving considerable attention in the scientific community. Concentrated in the leaf tissue of plants (and plant-based foods), many polyphenols work as antioxidants in the body to neutralize free radicals that can damage cells and potentially increase risk for disease. While clinical research has focused most on the cardiovascular, neurological, and metabolic benefits of certain polyphenols, the role that some of them play in digestive health is an ongoing area of research. 

The general mechanism of action for polyphenols is believed to involve the promotion of a healthy inflammatory response, neutralization of damaging free radicals, and a resultant positive impact upon the gut microbiome. In effect, the relationship of polyphenols to the gut microbiome appears to be bi-directional; polyphenols can impact composition of the gut microbiota and help balance good and bad bacterial growth, while gut microbes help metabolize polyphenols into compounds that are more easily absorbed. (The bioavailability and effects of polyphenols greatly depend on their transformation by components of the gut microbiota — lending further support to the theory that a “synbiotic” blend of polyphenols, prebiotics, and probiotics holds the most promise as a way to optimize their efficacy in a supplement, as we’ll discuss shortly.) 

Among the many foods rich in polyphenols, there is no “one” that delivers all the benefits of all the different types of important polyphenols. Spices, soy, coffee, tea, fruits, vegetables, nuts, chocolate, and wine are a few foods included in a study that identified a list of the top 100 polyphenol-containing foods. But because foods are complex mixtures of different compounds, and since it’s difficult for consumers to decipher which ones contain the best sources and quantities of healthy compounds such as polyphenols, supplements containing carefully selected types and quantities of polyphenols are worth consideration. 

Eden’s synbiotic blend contains five scientifically-vetted polyphenol ingredients, all with strong antioxidant properties associated with a wide array of beneficial health effects. On the digestive front, particular benefits include:

• Green and gold kiwi fruit extracts have been shown to benefit the growth of good bacteria, increase bowel regularity, and ease symptoms of GI distress.

•  A combined lychee and green tea extract is associated with reduced oxidative stress-induced inflammation and increased fat metabolism.

• Turmeric contains the ingredient, curcumin, which has demonstrated improvement in digestive comfort in patients with ulcerative colitis, IBD, and Crohn's disease. 

Key takeaways

A healthy gut is one that is free from inflammation and harbors a healthy gut microbiome that promotes a strong intestinal barrier. A healthy gut effectively absorbs nutrients and improves your energy and vitality. Stress, smoking, certain medications, and obesity can all negatively impact your gut barrier and contribute to gut inflammation. While it’s not the only factor, what and how much you eat, aka your daily dietary regimen, can significantly impact the health of your gut. Feeding your gut microbiome with prebiotic fiber, supplemented by key probiotics and polyphenols, can help you maintain gut health or get your gut back to a healthy state. To support optimum gut health, talk with your healthcare provider about an appropriate fiber-forward diet, avoid dietary fats and sugars, engage in stress-reducing activities, quit smoking, moderate your alcohol consumption, and make sure you’re getting enough sleep each night. Your gut, and your gut microbes, will thank you.