Is Your Gut Health Impacting Your Metabolism and Mood?
Friday, February 23, 2018
LifeTime WeightLoss in Samantha McKinney, gut health, leaky gut, mental health, mood

When feeling grumpy, down, irritable or otherwise in a “bad mood,” it’s easy to consider the cause purely circumstantial: tossing and turning all night, needy family members, never-ending work demands, getting cut off on the expressway — or a combination of all of the above. While these are all undoubtedly frustrating, it’s not often that we stop and think about our mood in relation to what is going on inside our body. Specifically, the gut.

If you’ve ever had butterflies in your stomach before a presentation or had to rush to the nearest bathroom during a stressful event, it’s probably no surprise that the gut and brain are intricately connected. Intuitively, most of us are aware that a mind-body connection exists, and yet it’s often hard to actualize that concept in our own lives. Instead of considering internal health when feeling down or having anxious feelings, the common societal stance is to charge forward, taking a mind-over-matter approach.

However, it seems that almost daily, new and exciting scientific literature unveils the surprising impact of digestive health on our mood. Consider the facts: an approximated 70 million of us have some sort of digestive disorder (and even more than that likely have some sort of imbalance), one in six of us have some form of mental illness (major depression being the most common), one in three of us will have anxiety at some point with one in five having it within the last year.1,2,3 To be clear: anxiety, depression and other mental disorders are serious medical issues that should not be confused with simply having a bad mood or a bad day. But these struggles can significantly impact our relationships and quality of life. And if you’re struggling, it’s safe to say that you’re not alone. Whether you are fighting the battle with a medical diagnosis or struggling with ongoing irritability or apathy, let’s pause and consider what steps can be taken to support gut health and set the stage for a healthy mind.



Our digestive tract is very much at the foundation of our overall health. Consider its importance. This long, hollow tube that starts with our mouth and ends, well, at the other end, is responsible for breaking down what we eat and drink, discerning what is actual nourishment (to be absorbed) and what is waste (to be passed through for eventual elimination). In addition, it has a gargantuan role in immunity and protecting us from the pathogens we ingest.

After chewing, food moves down the esophagus into the stomach, where acids and pepsin are released to get the food ready for the small intestine. The food progresses relatively slowly from the stomach into the small intestine, where along its approximate 20-foot length, enzymes and bile are released to break food down into individual components for absorption. And ancillary organs, such as the liver, gall bladder and pancreas, also impact what happens on the journey of food through the small intestine. Assuming all is well, nutrients are absorbed while other components (waste, fiber, etc.) then move into the large intestine, where we house several pounds’ worth of symbiotic bacteria. In the large intestine, water is reabsorbed, forming solid waste to eliminate through the bowels. But what does this have to do with our brain?



The gastrointestinal tract, or GI tract, is connected to our central nervous system and brain, and our gut hormones have an impact on the function of our blood-brain barrier.4 This barrier is an important filter, and is largely responsible for protecting brain function from chemicals that would otherwise pass through and cause damage.

Our small intestine lining plays a big role in determining what gets absorbed and what passes through. Think of it as a bouncer at a nightclub; it should let “in” (absorb) the nutrients needed for us to feel good and function well, while keeping “out” (retaining in the GI tract) undigested food particles, pathogens and toxins. When the lining is compromised by chronic, unmanaged stress; processed food products; underlying food sensitivities; or chronic use of certain medications, it can become too permeable, or leaky. This is referred to as “leaky gut” or “intestinal permeability” which can play a role in how we respond to outside stressors, such as work demands or getting cut off in traffic.5

Food reactions and sensitivities are a hot topic in nutrition circles right now, and for good reason. They can create havoc in the digestive tract, and in terms of mental health, an elimination diet approach could be one of many factors to consider when addressing aggression or antisocial behavior.6  While it may be considered a fad by many, a gluten-free trial, as well as a consideration of a dairy-free and soy-free diet, can be used to see how these particular foods impact an individual’s mental state (or not). Removing gluten, for example, has been shown to reduce schizophrenic symptoms in some patients.7 While avoiding traditional bread, pasta, cereal and other gluten-containing grains may seem daunting, the potential for symptomatic relief could make it well worth trying. Plus, with all the gluten-free alternatives and specialized restaurant menus, it’s easier today than ever to follow a gluten-free approach.

The integrity of our small intestine lining is also a significant determinant of how well we absorb and utilize vitamins and minerals. In the context of mood, this is especially important, as Vitamin B12, folate, zinc, selenium and more have all been implicated in mental health.8,9,10 Replenishing the status of these nutrients — not just from intake, but from absorption and utilization — is a non-negotiable in supporting a healthy mood.11 This is why great nutrition coaches are often sticklers on the quality and form of supplementation that is used. For example, in the case of depression (and dementia too), getting folate from a methylated form (like methyltetrahydrafolate) versus the synthetic folic acid form is recommended. (Go check your multivitamin label!) 12 Also note, certain key nutrients like Vitamin B12 (which should be methylated in the “methylcobalamin” form) and zinc (which should be chelated versus the cheaper oxide form), rely on adequate levels of acids and enzymes to be properly broken down. (Note: Life Time’s full suite of Men’s, Women’s, Performance and Prenatal multivitamins all meet these standards.)

Many of us also have lower levels of enzymes and a hindered ability to break these nutrients down to prepare them for proper absorption for our bodies to actually use, even if we’re taking in the right forms and amounts. Many clients choose to implement digestive enzyme support at mealtime to get more nutrient bang for their buck from their nutrition and supplementation plan. If you struggle with mood challenges, take heed, as nutrient deficiencies (such as Vitamin B12) can more than double the risk of depressive symptoms in some people.13 Mind your nutrient intake and absorption, and your mood may thank you.



Our gut also has what is called the enteric nervous system: its own system of nerves, often referred to as the “second brain.” It produces and uses neurotransmitters, such as serotonin, the “feel good” neurotransmitter. In fact, a staggering 90% of our serotonin is made in the gut.14 It also houses a large community of intestinal bacteria (which can be referred to as probiotics, gut flora or the gut microbiome) in the large intestine, or colon. And the gut has so much impact on metabolism that it’s considered to be an organ with 100 times the genetic material found in the human body.15 Not only do these bacteria have an impact on how many calories we extract and use from the foods we eat,16 but they also produce metabolically crucial nutrients and compounds such as Vitamin K, biotin and butyrate. In terms of our brain, an altered composition of gut flora, or having a pathogenic gut infection, can have significant implications. These range from associations with autism to cases of complete alleviation of psychiatric symptoms to antibiotic therapy that address gut imbalances.17,18

And while there are beneficial bacteria that we rely on, there are also harmful species to tame. Optimal brain health (and overall vitality) hinges on having a large diversity of the good guys, while keeping the bad bacteria and yeast in check. In fact, our bacterial balance can be a direct regulator of anxiety and depression.19  The not-so-beneficial bacteria, yeast and pathogens thrive on added sugar and produce their own waste and toxins, such as ammonia, which can actually create inflammation that impacts the brain and can lead to depressive symptoms.20 The good and protective bacteria, on the other hand, thrive on dietary fiber and prebiotics, which serve as food for the good probiotics. Focusing on fermented foods such as sauerkraut, kombucha, kim chi and fibrous vegetables, plus considering a probiotic supplement, can help the good bacteria flourish.

With that being said, some people report feeling worse when implementing fermented foods or foods higher in fiber. If you’re trying to optimize your gut bacteria and are feeling worse instead of better, it may be worth digging a little deeper. Gut bacteria, normally residing the large intestine, can sometimes overgrow up the digestive tract and into the small intestine. This is referred to as small intestine bacterial overgrowth, or SIBO, and is closely associated with IBS or irritable bowel syndrome.21

Those with SIBO often struggle with ongoing issues of bloating, diarrhea, constipation and excess gas. In the case of mental health, SIBO is important because an estimated 70–90% of IBS sufferers have some sort of mental disorder.22 SIBO cases often require medical treatment and a concurrent diet low in certain forms of carbohydrates that are easily fermentable by the bacteria in the small intestine. They are called FODMAPs, short for Fermentable Oligo, Di, Mono-saccharides and Polyols. And foods such as garlic, onion, apples and celery top the list of FODMAP offenders. In most cases, otherwise healthy FODMAPs are avoided for a course of several weeks while the underlying issue is addressed, and the bloating and abdominal discomfort from ingesting them is temporary and dose-dependent. If you decide to try a low FODMAP approach, and you observe a change in your digestive function, be sure to connect with a medical professional as there is likely something deeper going on.



It goes without saying that approaching mood challenges and struggles is complex and multifaceted. It often requires a holistic, 360-degree approach including medical care, therapy, psychological support, lifestyle considerations, stress management tactics, nutrition approaches, regular exercise, and when necessary, psychiatric interventions and medication. With that said, loving on our gut can only be of potential benefit.

In the grand scheme of things, it may be worth implementing some simple steps. They may include a modified elimination diet trial, taking in the right forms and amounts of vitamins and minerals, supporting proper nutrient breakdown and absorption, and fostering a healthy balance of beneficial gut bacteria to monitor changes in mood and outlook. Doing so could be a game changer in not only overt digestive function, but also in helping to calm chronic inflammation, support healthy detoxification, and optimize neurotransmitter balance.

As always, we’re here to help if you have questions about nutrition approaches or need support. Contact us anytime at


In health, Samantha McKinney – Life Time Lab Testing Program Manager


This article is not intended for the treatment or prevention of disease, nor as a substitute for medical treatment, nor as an alternative to medical advice. Use of recommendations in this and other articles is at the choice and risk of the reader.




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