Nutrition Series (Pt. 2) — Your Gut Will Take Care of You, If You Take Care of It

Out of sight should not mean out of mind. Our gut impacts every aspect of our day-to-day lives.

Apr 01, 2024

“We’re blind to our blindness. We have very little idea of how little we know. We’re not designed to know how little we know.”

Daniel Kahneman

Worth Listening To

This week’s Worth Listening To episode challenged much of what I thought I knew about the gut. In going down the rabbit hole of digestive health and our gut microbiome, I realized just how true the above quote is. Much of what I had previously learned from nutrition courses, nutritionists, and articles were either wrong or barely scratched the surface.

The major flaw in high-fat, low-carb diets (keto, for example)
Incredible benefits of fermented foods (major caveat: the microbes have to be alive; alcohol does not count)
Where fiber plays an important role
Dangers of chemicals, industrial cleaning agents, and potential benefits of being a little dirty.

Conversations With a Personal Trainer

Here are two of the many wonderful conversations I had last week:

Conversation 1: “Sometime in the last 5-7 years, I’ve felt this duty to teach kids how to think critically.” I had a magnificent conversation with this client about critical thinking (he teaches high schoolers). It was on the day Daniel Kahneman passed away, and since he was on my mind, we discussed the potential dangers of heuristics and taking shortcuts.

The second conversation involved one of the best short videos I’ve watched, which you can find at the bottom of this edition. It demonstrates the value of thinking for yourself. Plus, I learned the term “Socratic questioning,” which was very cool.

Both conversations were wonderful reminders that many shortcuts often lead to short-lived results. Cheating on a test may give you a good score, but you haven’t gained the knowledge to make an informed decision; cheating on your health may help you lose weight, but you haven’t developed the habits to lead a healthy lifestyle.

The Insidious Nature of Gut Inflammation

I will likely forever reference Kyla’s article about language, words, and distrust. The more we hear the same words over and over again — like hearing a well-told joke the first time, and then the tenth — the less impactful those words become. When you hear the word inflammation, what comes to your mind?

I’ll be the first to admit I used to discount inflammation as overused and meaningless— a term marketers love to use to sell products. Wow, was I wrong. Although perhaps overused, inflammation wreaks absolute havoc on the body, including being a leading contributor to metabolic diseases, the key focus of today’s piece.

To illustrate the varying pervasiveness of inflammation, think of the last time you took ibuprofen. Why did you take it? Whether it was for a headache or back pain, the reason is the same: inflammation. In both cases, your body releases prostaglandins to heal the affected site. While vital for healing, an excess concentration of prostaglandins can indirectly cause inflammation and pain. Ibuprofen is an NSAID or non-steroid anti-inflammatory drug that targets the compounds that release prostaglandins, thereby reducing inflammation and pain.

Gut inflammation works differently. Think of your digestive tract, specifically your large intestine, as a giant ecosystem, like a forest. A thriving forest is home to millions of living organisms, from plants to bears and everything in between. For this ecosystem to thrive, it needs balance.

Throughout the 20th century, wolves were hunted to near extinction in Yellowstone National Park. As a result, the elk population ran rampant. Elk fed on the land uncontested, preventing new trees and plants from growing, leading to significant downstream effects. In the 1990s, the federal government released 30 wolves in Yellowstone National Park. Almost three decades later, Yellowstone’s ecosystem has largely been restored.

If we don’t have the necessary nutrients in our diet, the mucus lining our intestines weakens, and our intestinal walls become permeable, allowing waste to seep into the body. The ecosystem falters. In Yellowstone, this meant the destruction of much of its vegetation and the departure of entire species. In our bodies, it means a significantly greater risk for metabolic syndrome, diabetes, certain cancers, and cardiac disease.

“It takes a long time for a trait to evolve, but not a long time for traits to devolve.” — Andrew Huberman in this week’s Worth Listening To.

A Giant Ecosystem Within Our Gut

Our gut microbiome is an ecosystem comprised of various bacteria, viruses, and other living organisms. These organisms live within our body’s sewer system and play an essential role in absorbing nutrients, preventing disease, strengthening our immune system, and sending signals to the rest of our brain through what is known as the gut-brain axis. What sustains a healthy microbiome, and why is sustaining it vital for our health?

Our gut eats what we eat. But just as protein is vital for muscle protein synthesis, fiber is the necessary nutrient for our gut to thrive. Why?

There are two different types of fiber: soluble and insoluble. Dr. Robert Lustig summarizes their role brilliantly:

“You eat 160 calories of almonds, how many of those do you absorb? 130. You eat 160, you abosrb 130, where’d the other 30 go? Turns out the fiber, both soluble and insoluble fiber, forms a gel on the inside of your intestine. The insoluble fiber, the cellulose forms a fish net, a lattice work. The soluble fiber, which are globular, plug the holes in that fish net. Together, they form a secondary barrier. And that prevents absorption of those 30 calories. So yes, 130 get absorbed, but many of them don’t. They end up going further down in the intestine to the next part, called the jejunum. And that’s where the microbiome is… we’re always eating for 100 trillion. They have to eat. What do they eat? They eat what you eat. The question is how much should you get versus how much should they get. Well if you ate almonds, they’re getting those 30 calories. Because of the fiber.

Soluble fiber, in particular, is vital for its role in producing short-chain fatty acids (SCFAs). SCFAs are metabolites, meaning they are necessary in the process of converting the food we eat into energy. There are three key SCFAs our microbiome produces, if we feed it properly. Each one plays a vital role in our body:

Acetate plays a crucial role in enabling our body to metabolize fats.
Propionate is important for the production of glucose by the liver.
Butyrate is the big one. It acts as an anti-inflammatory for our gut and protects the mucus layer, and thus, waste in our gut leaks into our body. As a result, it serves a major role in preventing colon cancer.

Is Eating More Fiber Enough?

You may be reading this thinking, “So, all I have to do is eat more fiber?” To some degree, yes. However, there is a major flaw with this reasoning and something I learned in the research for this piece. Because of the reduced fiber intake of North American diets — not to mention our heavy reliance on antibiotics — it’s estimated we have significantly reduced the amount of the necessary microbes for optimal gut health. According to both this 2022 study and this week’s recommended podcast episode, diets low in fiber over long periods of time can result in a depletion of these microbes.

How do we replenish these microbes? It takes time. Think back to the wolf example in Yellowstone National Park. The wolves began eating the elk, the elk population decreased, vegetation began to grow, birds and beavers returned, water levels rose, fish returned, and suddenly you have a balanced ecosystem. That is, if “suddenly” means more than 25 years.

Fortunately, it shouldn’t take you quite that long. But it’s important to know that results will happen gradually. Furthemore, not all fiber is created equal. Certain fibers play much greater roles in the production of SCFAs. Meanwhile, healthy bacteria in our gut are needed to ferment the carbohydrates we eat into these SCFAs.

Answering the Pre and Probiotic Debate

If this is all incredibly confusing for you, good. I enjoy having company in the Thoroughly Confused Club. Fortunately, all we need to know is what on earth we’re supposed to do about it.

You’ve likely heard of prebiotics and probiotics. The supplement industry has made enormous noise about both. In 2022, the prebiotic industry generated over $11 billion in revenue, while the probiotic industry generated a staggering $62 billion.

What are they, and why are they generating so much attention?

Prebiotics are fiber. Specific kinds of fiber that help produce SCFAs. The most common and highest-quality prebiotics are found in plants, nuts, and legumes.
Probiotics are the microbes that live in our gut. With the help of the prebiotics, they feed on the food you eat to produce those vitally necessary SCFAs.

We need both. Prebiotics create the necessary environment for probiotics to survive and thrive. While we’ve discussed fiber and its role as a prebiotic, how do we get more probiotics? Fermentation.

Fermented foods are an incredibly good source of those microbes we need. Foods like yogurt, unpasteurized cheese, kefir, sauerkraut, kombucha, and pickles. However, for these probiotics to help, they have to be alive. What do all of these foods have in common? They need to be refrigerated. If you buy fermented foods in cans or bottles (alcohol), the microbes are dead and won’t help your gut.

My wife and I recently bought tea. It’s delicious. But on the package, it says probiotics in big, bold letters with a line underneath, “Supports Healthy Digestion.” Umm… no. I don’t think so. That goes to a much larger issue about labels and companies being able to say whatever they want, but we’ll leave that for another time.

How much fiber and fermented foods do you need? The general recommendation for fiber is 15 or 16 grams per 1,000 calories you consume. For most of us, that’s roughly 25-35 grams per day. If your diet is low on both, start by adding both in a little at a time. I made the mistake of going overboard on my fiber intake when I started this process. Major rookie move. Unless you want to be sick to your stomach and spend much of your day on the toilet, I don’t recommend that approach. Similarly, with fermented foods, start slowly and add more over time.

In closing, our gut is little different than Yellowstone. Yellowstone needed the wolves to stem the excess population of elk just as we need prebiotic fiber and probiotic microbes to reduce inflammation in our gut. Both create a healthy, balanced ecosystem. It took Yellowstone more than 25 years to begin flourishing. How long will it take you?

Other Learning

First, I want to say farewell to Daniel Kahneman. His book, Thinking Fast and Slow, remains one of my favorite books, and his conversations on various podcasts have further helped me avoid the pitfalls my former self was prone to. You can find more here (his 4-part conversation with Annie Duke, Michael Mauboussin, and Josh Wolfe is among my top all-time favorite podcast conversations):