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Gut Health: Influencing Immunity, Disease, Mental Health, Body Composition, & More

You probably know by now that your gut is the foundation of your overall health. Maybe you heard your neighbor talk about probiotics, or read an article online talking about how yogurt is an important part of digestive health (can’t help but see Jamie Lee Curtis’ face in the Activia commercial…). 

What may feel a little more fuzzy is WHY exactly gut health is important and what can help and hurt your gut health. If disease often begins in the gut, don’t you think we all need to be educated in taking care of it? Here is the breakdown:


Gut health affects immunity:

The gut is also an important site of immune function, with over 70% of the body’s immune cells located in the gut. Research has shown that the gut microbiota plays a crucial role in regulating immune function, and that changes in the microbiota can lead to immune dysfunction and increased susceptibility to infection. Ironically, after a round of antibiotics to fight an infection, you may be even more susceptible to another, so make sure to give it special attention after taking a round. 

Gut microbiota influences disease:

There is growing evidence to suggest that changes in the gut microbiota can contribute to the development of a range of diseases, including obesity, diabetes, inflammatory bowel disease (IBD), and even certain types of cancer. For example, studies have found that individuals with IBD have a less diverse gut microbiota than healthy individuals, suggesting that the microbiota may play a role in the development of the disease. As stated above, the gut is home to a large portion of the body’s immune cells, and imbalances in the gut microbiota can affect the immune system and contribute to conditions such as autoimmune disorders.

Intestinal permeability plays a big role in this. Also known as “leaky gut,” it refers to a condition in which the lining of the intestinal wall becomes more permeable than normal, allowing substances such as bacteria, toxins, and undigested food particles to leak into the bloodstream. This can trigger an immune response, leading to inflammation and potentially contributing to the development of various diseases. Leaky gut is caused by a number of things, such as medications, poor diet, food sensitivities, stress, environmental toxins, etc.

The gut and the brain are a 2-way street:

Research has also shown that the gut microbiota can communicate with the brain through the gut-brain axis. This communication is thought to be important for regulating mood, behavior, and even cognitive function. Studies have found that changes in the gut microbiota can affect mood and behavior in animal models, and that probiotics (beneficial bacteria) may have a beneficial effect on anxiety and depression in humans.

Serotonin is a neurotransmitter that plays a key role in regulating mood, appetite, and digestion. You often think about it being produced in the brain, with it being a “neuro”-trasnmitter after all, but did you know that according to the NIH approximately 95% of serotonin is produced in the GUT? It has a role in the gut too, like in the regulation of gut motility (aka the motor behind keeping things moving) and secretion of things like digestive juices.

Studies have found that the gut microbiota can affect serotonin production through several mechanisms. For example, certain types of bacteria can produce or consume neurotransmitters like serotonin, which can affect the overall levels of the neurotransmitter in the gut. The gut microbiota can also affect serotonin production indirectly by modulating the immune system, which can in turn affect serotonin levels. There is also evidence to suggest that alterations in the gut microbiota can affect the expression of genes involved in serotonin production, as well as the uptake and transport of serotonin in the gut. 

Additionally, serotonin may be involved in the development of conditions such as irritable bowel syndrome (IBS) and other gut-related disorders. Studies have found that individuals with IBS (and therefore altered gut bacteria) have altered serotonin signaling in the gut, suggesting that these factors may contribute to the development of the condition.

If you’re dealing with affective disorders such as depression or anxiety, it is CRUCIAL to pay attention to your gut health.

Gut health affects body composition:

The gut is responsible for absorbing nutrients from the food we eat. This includes macronutrients like carbohydrates, proteins, and fats, as well as micronutrients like vitamins and minerals. Adequate nutrient intake is essential for maintaining muscle mass and bone density.

The gut also plays a role in regulating energy balance, or the balance between calories consumed and calories expended. When we consume more calories than we expend, the excess energy is stored as fat, leading to weight gain. Conversely, when we expend more calories than we consume, we lose weight. The gut plays a role in regulating appetite and satiety, which can influence our food intake and energy balance. It does so by producing hormones that affect appetite, including leptin (the fullness hormone), ghrelin (the hunger hormone), and peptide YY (also plays a role in decreasing appetite). A disrupted gut microbiome can lead to things like leptin resistance, meaning you don’t feel full as quickly as you should, which can lead to overeating and weight gain.

The actual type of the microbes in your gut can influence body composition, too. Studies have shown that certain gut bacteria are associated with higher levels of body fat, while others are associated with lower levels of body fat. The gut microbiota can also affect energy metabolism and inflammation, both of which can influence body composition. Particular strains that have been associated with lower body weight include Bifidobacterium, Akkermansia muciniphila, Lactobacillus gasseri, Faecalibacterium prausnitzii, and Roseburia.


The foods that we eat can have a significant impact on the gut microbiota and overall gut health. For example, a diet high in fiber can promote the growth of beneficial bacteria in the gut, while a diet high in inflammatory fat and sugar can have a negative impact on gut health. Studies have also found that certain dietary components, such as polyphenols found in fruits and vegetables, can have a prebiotic effect and promote the growth of beneficial bacteria in the gut. However, diet isn’t the only factor. There are several lifestyle factors that also influence the state of your gut. 

These diet and lifestyle factors may help IMPROVE gut health:

  • Fermented foods: Fermented foods like kimchi, sauerkraut, kefir, yogurt, and kombucha contain beneficial bacteria (probiotics) that can help improve gut health. A more extensive list can be found here
  • Prebiotic foods: Prebiotics are types of fiber that feed the beneficial bacteria in your gut. Foods high in prebiotics include garlic, onions, asparagus, artichokes, bananas, and oats.
  • High-fiber foods: Foods high in fiber can help improve gut health by promoting regular bowel movements and supporting the growth of beneficial bacteria. Examples of high-fiber foods include whole grains, fruits, vegetables, seeds like flaxseeds, and legumes.
  • Bone broth: Bone broth is made by simmering bones and connective tissue from animals, and is rich in nutrients that can help improve gut health, such as collagen, gelatin, and amino acids.
  • Omega-3 rich foods: Omega-3 fatty acids can help reduce inflammation in the gut and promote a healthy gut microbiome. Foods rich in omega-3s include fatty fish like salmon, chia seeds, flaxseeds, and walnuts.
  • Nuts and seeds: Nuts and seeds are high in fiber and healthy fats, which can help promote gut health. Examples include almonds, pistachios, chia seeds, and flaxseeds.
  • Fruits and vegetables: Fruits and vegetables are rich in fiber, vitamins, and antioxidants, which can help promote a healthy gut microbiome. Aim for a variety of colorful fruits and vegetables to get a wide range of nutrients.
  • Reducing stress: stress is a big factor in loosening the tight junctions in your gut and leading to leaky gut. Reducing stress can have a major impact on gut inflammation.
  • Exercise: movement promotes lymphatic drainage which helps remove waste from the body, reduce inflammation, stress, promotes motility, and even promotes beneficial bacteria growth.
  • Getting proper sleep: adequate sleep allows the body to properly perform “maintenance” in the gut, repairing any damage done and releasing growth hormone, which has a positive affect on the gut.
  • Supplements: there are several therapeutic supplements to help heal the gut. Find a list here.
  • Avoiding food sensitivities: eating foods you are sensitive to can cause chronic stimulation of the immune system and therefore chronic inflammation. Identifying them and eliminating them either permanently or during a healing phase is a helpful way to ensure you aren’t dripping gasoline on the fire!

These factors can NEGATIVELY affect gut health:

  • Poor diet: A diet high in processed and high-sugar foods, and low in fiber and nutrients, can lead to an imbalance in the gut microbiota, inflammation, and other gut-related problems.
  • Antibiotics: Antibiotics can kill both harmful and beneficial bacteria in the gut, leading to an imbalance in the gut microbiota and potentially causing digestive problems.
  • Stress: Chronic stress can affect the function of the digestive system and alter the gut microbiota, leading to gut-related issues.
  • Lack of physical activity: A sedentary lifestyle can contribute to gut-related problems, as physical activity is important for maintaining a healthy gut microbiota and promoting healthy digestion.
  • Too much physical activity: exercise is typically a “good kind of stress” for the body, but if you’re in a chronically stressed state already and doing a lot of high intensity exercise, you may be doing more harm than good.
  • Alcohol and tobacco use: Alcohol and tobacco can both disrupt the gut microbiota and cause inflammation in the gut.
  • Chronic use of certain medications: Certain medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs), can irritate the lining of the gut and contribute to gut-related issues.
  • Lack of sleep: Chronic sleep deprivation can affect the gut microbiota and contribute to gut-related problems.
  • Environmental toxins: Exposure to certain toxins, such as pesticides, can affect the gut microbiota and contribute to gut-related issues.

Stay tuned for more about how to improve your gut health, including specific foods you can and should eat every day, recipes to help, supplements to use, and more!

Did you learn something new? Share in the comments below!


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Gut Health: Influencing Immunity, Disease, Mental Health, Body Composition, & More

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