Gut Health Fundamentals

Poor gut health has been linked to conditions as wide-ranging as cancer, obesity and other metabolic problems, heart disease, anxiety, depression, autism, autoimmunity, ulcers, IBD, liver disease, systemic infections, and more.

There are two main aspects of gut health that are not only critically important for overall health, but also easily improved through modifications to diet and lifestyle.  These are gut barrier health (poor gut barrier health is called “leaky gut” or more technically, “increased intestinal permeability) and gut microbiome health (a disordered gut microbiome is called “gut dysbiosis”, a specific example of which is Small Intestinal Bacterial Overgrowth, or SIBO).

The Gut Barrier

Gut is the colloquial term for the gastrointestinal system, an organ subsystem composed of the esophagus, stomach, and small and large intestines. The gut is a major component of the digestive and excretory system—the biological system composed of the entire gut as well as the liver, pancreas, gallbladder, tongue, and salivary glands—which is responsible for digesting the food we eat, absorbing nutrients, and expelling waste.

The food we eat is digested inside the gut as it travels from one end to the other. Supplying nutrients to the body is clearly a very important job. Without the gut to accomplish this vital function, we could not survive. However, digestion is just the tip of the iceberg when it comes to the gut’s contribution to our health!

The gut has the very tricky job of letting nutrients into the body while keeping bacteria, viruses, parasites, other pathogens and toxins from entering the body. To achieve this function, the gut is equipped with an array of physiologic defense mechanisms, including mucus, digestive enzymes, acid, and about 80% of our immune system!

When the gut barrier becomes more permeable, or “leaky”, pathogens and toxins can enter the body in an uncontrolled way. This activates the immune system, causing both generalized (bodywide) inflammation and targeted immune activation (the adaptive immune system). It’s this activation of the immune system, in addition to toxin exposure, that is the link between gut barrier health and chronic illnesses. See also What Is A Leaky Gut? (And How Can It Cause So Many Health Issues?), 8 Nutrients for Leaky Gut, What Should You Eat To Heal a Leaky Gut?, and Which comes first: the leaky gut or the dysfunctional immune system?.

The Gut Microbiome

The gut is a biological niche, home to a diverse array of microbes that influence nearly all aspects of human biology through their interactions with our bodies. We have a symbiotic relationship with these microbes, collectively referred to as our gut microbiome—in exchange for food and shelter, they contribute to our wellbeing by performing diverse functions essential to our health.

Our gut microbiota help us digest food, produce chemicals that improve the health of the cells that form the gut barrier, directly regulate the immune system, and they can even influence brain health by producing neuroactive chemicals that are absorbed into the bloodstream and travel to the brain. A healthy diversity of the right kinds of microorganisms in the gut is one of the most fundamental aspects of good health. See also What Is the Gut Microbiome? And Why Should We Care About It?

Our gut bacteria also directly control the integrity of the gut barrier by regulating important proteins that bond the cells that form the gut barrier together. These effects aren’t limited to the gut either: recent studies have shown that our gut bacteria can regulate the permeability of epithelial barriers elsewhere in the body, including the blood-brain barrier (yep, our gut bacteria control how leaky the blood-brain barrier is), the lung barrier, and the skin barrier. So, an essential aspect of restoring gut barrier health is cultivating a healthy and diverse gut microbial community.

The microorganisms in our guts also help to maintain the delicate balance required by our immune systems, keeping the various populations of immune cells in check and modulating their activity. Achieving a healthy balance in the immune system is therefore also reliant on having a healthy gut microbiome.

Supporting Gut Health

About 90% of all disease can be traced back to the health of the gut barrier and gut microbiota.  Fortunately, our diet and lifestyle choices have an enormous direct impact on both the integrity and health of our gut barriers and the composition of our gut microbiome!  That means that, with some changes to the foods we’re eating and lifestyle priorities, we can have a tremendous impact on our gut health, thereby improving whole body health.

The Cliffsnotes? In general, supporting a healthy gut barrier and microbiome requires consuming a moderate amount saturated fat; a balanced ratio of omega-3 to omega-6 polyunsaturated fats; a diversity of fiber types and phytochemicals from a wide range and large quantities of whole fruits, vegetables (eating at least 8 servings daily), nuts and seeds; and modest amounts of animal foods (including fish, shellfish, poultry, and grass-fed red meat).

Gut health superfoods include: vegetables of all kinds (and cruciferous vegetables, mushrooms, roots and tubers, alliums, and leafy greens are independently beneficial, meaning we want to eat from each family most days), fruit of all kinds (apple family fruits, citrus, and berries are independently beneficial, nuts and seeds (especially walnuts, pistachios, chestnuts and almonds), A2 dairy, chocolate, extra virgin olive oil, fish, shellfish, honey (in moderation) and other bee products, fermented foods, edible insects, coffee, green and black tea, and bone broth.

In addition, our gut barrier health and gut microbiome composition are sensitive to our hormones (especially vitamin D, see Vitamin D), nutrient status, stress levels, sleep, and activity (see The Paleo Lifestyle).

I am writing a new book that will go into nitty gritty detail on this topic, but in the meantime, you can get into some of the details in: The Importance of Vegetables, The Importance of Nutrient Density, The Amazing World of Plant Phytochemicals: Why a diet rich in veggies is so important!, Polyphenols: Magic Bullet or Health Hype?, Nuts and the Paleo Diet: Moderation is Key, The Fiber Manifesto-Part 1 of 5: What Is Fiber and Why Is it Good?, The Fiber Manifesto-Part 2 of 5: The Many Types of Fiber, The Fiber Manifesto-Part 3 of 5: Soluble vs. Insoluble Fiber, Coffee as a Mediator of Health & Longevity, Why Root Veggies Are Great for the Gut Microbiome, The Importance of Fish in Our Diets, Why Fish is Great for the Gut Microbiome, Why Bee Products Are Great for the Gut Microbiome, Why Crickets Are Great for the Gut Microbiome, The Health Benefits of Fermented Foods, Olive Oil Redemption: Yes, It’s a Great Cooking Oil!, Why Fruit is a Good Source of Carbohydrates, Saturated Fat: Healthful, Harmful, or Somewhere In Between?, Conjugated Linoleic Acid (CLA): A Rockstar Nutrient and Why Broth is Awesome. Phew!

And, even more exciting, I’ve included this detailed information on gut health in…

Announcing the Gut Health Fundamentals Online Course!

In this online course, I dive deep into gut barrier and gut microbiome health, highlighting how the health of our gut impacts our overall health, and gut health nutrients, superfoods and lifestyle factors that support a healthy and diverse gut microbiome and robust gut barrier.

Get Instant Digital Access

This online course includes 3 3/4 hours of video lecture, including downloadable and printable PDFs of my presentations slides.  The topics I covered in detail include:

• How gut health impacts whole health
• The gut barrier and the gut microbiome
• Nutrients for gut barrier health
• Food compounds that damage the gut barrier
• The influence of lifestyle on the gut barrier
• Supplements for gut barrier health
• Why we need a healthy gut microbiome (and what that looks like)
• Optimal diet for a healthy gut microbiome
• Food compounds that feed gut dysbiosis
• Gut microbiome superfoods
• How lifestyle factors alter gut bacteria
• Keys to gut health

In this online course, I give a detailed overview of the gut, its functions, its connectivity to other systems, and what defines a healthy gut. By zooming into the gut barrier at the cellular and subcellular levels, I highlights nutrients essential to gut barrier health, food compounds that interfere with barrier regulation or which damage the gut barrier, and how lifestyle factors impact gut health via the endocrine system.

The gut microbiome performs diverse functions essential to our health, and without a doubt, supporting our gut microbes is one of the most fundamental aspects of good health. However, doing so is much more nuanced that simply upping fiber intake. This online course expands on common knowledge related to gut microbiome health to hone in on the many surprising gut microbiome superfoods that just don’t get enough play in the Paleo or AIP communities, but which should be elevated in status.  I conclude this online course with a discussion of the impact of diet and lifestyle factors on the gut microbiome with a focus on best practices to maximize microbial diversity and support the growth of key probiotic organisms.

Want an upgrade? Because I know you’re super excited to dive into this enlightening content, I want to mention that you can get all four of my new online courses (Introduction to Nutritional Sciences, Therapeutic Paleo Approach, Healthy Weight Loss, and Gut Health Fundamentals) plus an awesome bonus lecture on Fad Diet Recovery in The Foundations of Health Online Course Collection. This online course collection includes a total of 15 (!) hours of video lecture, including downloadable and printable PDFs of my 650(!) presentations slides.

Learn more about The Foundations of Health Collection here.