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  • Denise Scott

What's the Gut Got to Do With Immunity?

I was a guest recently for a podcast, Small Changes, Big Shifts, with Dr. Michelle Robin (9/25/23). You can find it on Spotify, Apple and Google Podcasts, or @ The topic is the gut and immunity. I decided to turn it into a blog article! This article builds on last week's post about prebiotics and probiotics.

An interesting fact: 70-80% of our immune cells reside in the gut! The gastrointestinal (GI) tract is a major player in the development and health of our immune system.

A depiction of the intestines held in front of the abdomen.

Think about it: it is through our GI tract that we are introduced to new, outside microorganisms, good and bad, through our mouth and nasal passages. These make their way through our gut, where a fascinating interplay exists between the lining of our intestines and the trillions of microorganisms that live within - the microbiota. (See 11/9/22).

The roles of the gut microbiota are depicted here; controlling the immune system is one of the most important.

This ongoing communication between our gut lining (the epithelium) and our microbiome is where immune signaling occurs every time a new bacteria or virus enters our body. What happens in our gut signals to the rest of our body whether to destroy the new bacteria or to allow it to reside safely within us. If this communication breaks down or becomes impaired, inflammation, infection, and disease can develop.

Numerous diseases are associated with an unhealthy microbiome. These include type 2 diabetes, metabolic syndrome, obesity, allergies, asthma, autoimmune disease, cardiovascular disease, inflammatory bowel disease, and some cancers. Research on the microbiome will change how we diagnose, modify, and eventually treat diseases.

Keeping your gut healthy may keep your body healthy!

Trillions of microorganisms - bacteria, viruses, and yeast - make up the microbiome; research has found that the types of microorganisms (species) and the ratio of these species to each other determine whether the microbiome is healthy or unhealthy.

In other words, both good and bad bacteria are in our gut, which can promote wellness or illness.

Multiple factors influence the composition of the microbiome, including:

  • Age

  • Genetics

  • Gender

  • Culture

  • Nutrition

  • Environmental factors

  • Socio-economic factors

  • Stress

  • Antibiotic use

An unhealthy diet, stress, and antibiotics can negatively impact these gut bacteria, leading to inflammation and disease development.

Some of the bacteria in our gut make products from food. Dietary fiber provides prebiotics or food for these bacteria, which have the enzymes to digest and ferment the fiber. This process leads to the production of short-chain fatty acids (SCFAs), which are anti-inflammatory, help regulate the immune system, and are antimicrobial. A deficiency of SCFAs may affect inflammatory bowel disease and colorectal cancer development.

Our gut microbiome begins developing at birth. Once a baby has weaned from breast milk or formula and begins eating solid foods, changes occur in response to diet. The first three years are crucial in microbiome development. Changes take place that will last into adulthood and may influence future disease development.

Macronutrients - carbohydrates, fats, and protein - determine which bacterial species will develop and multiply.

  • Simple vs. complex carbohydrates

  • Saturated vs. unsaturated fats

  • Animal vs. plant-based proteins

Dictate which species develop.

A parent can influence early on whether their child’s gut environment becomes healthy or unhealthy.

Although changes continue to occur into teens and adulthood, the microbiome becomes predominantly established by three.

How can we affect our microbiome to influence our well-being and our children’s health?

We know that nutrition has a vital impact on the makeup of the gut microbiome, playing a crucial role in health and disease development.

Increasing dietary fiber is one of the best ways to promote the growth of good bacteria that directly affects our immune system.

We get this fiber from whole plant-based foods such as fruit, vegetables, whole grains, legumes, and nuts. Ideally, it is best to get this from food, not supplements, since these foods provide additional nutrients, such as vitamins, minerals, and antioxidants.

Fiber is food for our gut bacteria and provides prebiotics for the microbiome. We can’t digest this fiber, but our gut bacteria can to make SCFAs.

Photo of foods for a healthy gut. These foods have fiber or probiotics, and come from vegetables, fruit, whole grains, nuts, and fermented foods.

For kids, a general rule is to add 5 to your child’s age to find the number of grams of fiber they should have daily. Divide this total over the course of the day with meals and snacks. When increasing fiber, increase water to aid digestion.

Following an anti-inflammatory diet is also beneficial.

Foods that contribute to inflammation include:

  • Sugar

  • Saturated fats

  • Processed foods

  • High omega-6 content

  • Refined or processed grains such as white rice and white bread

These inflammatory foods decrease the diversity of the gut bacteria, while high-fiber foods increase the diversity.

A healthy diet of fruits, vegetables, whole grains, and legumes creates a healthy microbiome. Prebiotics and probiotics are beneficial and can come from whole, natural foods.

Include as many plant-based foods as you can in your diet while minimizing animal products.

One of the best things a parent can do is critically evaluate your child’s diet. The first step is to eliminate sugar-sweetened beverages and minimize added sugar intake. The majority of sugar consumption comes from sugary beverages. These include soda, energy drinks, sports drinks, dessert coffees, juices, etc.

The next step is to ensure your child gets fiber in their diet with fresh fruits, vegetables, beans, and whole grains. It is best to get what we need through whole foods rather than supplements.

Finally, minimize processed foods and read food labels. The fewer ingredients (5 or fewer), the better. Fill your diet with fresh produce and become familiar with the Mediterranean diet, one of the best diets available. I don’t advocate any diet for a growing child that eliminates entire food groups since deficiencies are likely to occur.

Feed your child’s future health by feeding your child’s gut!

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