In the world of probiotics and gut health, a few publications serve as the go-to resources for people looking to nourish and support their friendly flora within. The Good Gut: Taking Control of Your Weight, Your Mood, and Your Long-Term Health, by Justin and Erica Sonnenburg, is one such book. With user-friendly scientific explanations, recipes, and a menu plan—all in an easy-to-read, relatable format—The Good Gut is an excellent primer for anyone (gut health novices and experts alike) who is ready to take control of their microbial health.
Although we could (and don’t worry, we will!) write countless articles on all we learned from this fascinating book, these are the seven lessons that gave us our very own “aha” moments:
1. We have a symbiotic relationship with A LOT of bacteria.
Every single one of us has a microbiome as unique as our individual fingerprints, full of trillions of bacteria in and on our body. In fact, if you were able to line up all the bacteria in your body end to end, they would reach all the way to the moon! The majority of bacteria in your body reside in the large intestine, at a density of 500 billion cells per teaspoon of intestinal contents. Other fun facts? You can find more microbes on your hand than there are people in the entire world, and if you were able to gather all of the bacteria on Earth together into one lump, the biomass would be bigger than all of the plants and animals in the world—combined.
2. Our microbiota has its own genome.
A genome is the complete set of genetic instructions for an organism, and unless you’re an identical twin, your genome is unique to you. Each microbe in our body also has its own genome, and our microbiome as a whole provides an additional 3-5 million microbial genes that function as extensions of our genome. Why does this matter? Our body relies on and benefits from all these “extra” genes to make up for deficiencies in our own genome—one example is our microbes’ ability to break down indigestible fiber into beneficial compounds like short-chain fatty acids that benefit our health. When you consider that our microbiome contains 100 times more genes than our human genome, it means that a whopping 99% of the genetic material that we have access to is moldable for our benefit.
3. The infant microbiome is very wise.
During the third trimester of pregnancy, a woman’s microbiota composition changes to promote bacteria that can extract more calories from food and store them as extra weight. But shortly after birth, a baby’s microbiome resembles a mom’s first trimester microbial make-up, meaning that the infant gut selects which microbes to keep and which to ignore in its determination to set up a thriving community of beneficial bacteria. What’s more, HMOs (human milk oligosaccharides) in breast milk provide sustenance for both Bifidobacteria (which dominate the breastfed infant’s gut) and for plant-eating bacteria that need to flourish when a baby starts eating solid food. And when baby does get his first bite of yummy peas? Within just one day, these new bacteria that have been lying in wait are ready to explode on the scene—this is the most dramatic change to the microbiome in the first two years of life.
4. Bacteria make a huge difference in our immunity.
Our gut microbiota tune the dial of our immune system, controlling its overall responsiveness. The friendly flora living in our gut communicate with our immune cells in the intestine, which can then leave the gut and relocate to other places in the body. In addition, beneficial bacteria help populate gut tissue with T-regs, immune cells that keep overzealous immune responses in check. And, even many of the “inhospitable” microbes we encounter aren’t destined to cause major problems—they function to tickle our immune system, initiating mini-responses that rev its engine and keeps it at the ready. For example, some well-known harmful bacteria, like H. pylori, can cause issues in certain individuals but in others, helps regulate the immune system to an optimal set point.
5. Our microbes need a “Big MAC” diet.
The helpful bacteria in our microbiome depend on dietary fiber, called microbiota accessible carbohydrates (MACs), to survive and reproduce. Friendly flora ferment MACs in our gut into short-chain fatty acids that have a number of beneficial effects on our health, like helping our intestine accumulate T-reg immune cells. Green bananas, a potent source of MACs, can promote the growth of beneficial bacteria in the gut—even without a source of probiotics. Unfortunately, our modern Western diet is very low in fiber. The last remaining tribe of full-time hunter-gatherers, the Hadza of Africa, consume around 100-150 grams of fiber per day—this is in stark contrast to Americans’ typical 10-15 grams! The problem? If we don’t eat enough fiber, our microbes can feast on our gut’s mucous layer, weakening our gut barrier and affecting our immune function. Fortunately, increasing MACs (abundant in tons of plant foods like onions, garlic, Jerusalem artichoke, bananas, and apples) leads to a rapid shift of microbiota.
6. It’s all about diversity.
As a society, we are suffering from a lack of diversity in our microbiomes. The average American adult has about 1,200 species of bacteria in their gut, but the average Amerindian from the Amazonas of Venezuela boasts nearly 1,600 species. And, Western children tend to have less diverse microbiomes than children living in less modern environments. This is a major problem because the richness (or diversity) of our microbiome is a better predictor of lifelong health than our body weight. Loss of diversity in the microbiome is due to our overly clean lifestyles, our reliance on antibiotics, our birth and infant care practices, and a lack of fibrous plants and food-borne microbes in our diets.
7. Stress and aging impact our microbes, too.
When we’re stressed, our nervous system slows down our digestion, and only the microbes that are adapted to this decreased food transit time will flourish, reducing the overall diversity of our microbiome. In other words, our levels of stress dictate which types of microbes can survive in our gut. Digestive irregularity and the switch to a low-fiber diet, common occurrences as we age, also affect which friendly flora can proliferate in our gut, leading to decreased overall microbial diversity. On the other hand, a high-MAC diet can protect the microbiome from age-related decline and associated health issues. The authors even postulate that the notoriously anti-aging effects of social connections could be due to increased contact with microbes from new people, places, and experiences—all of which contribute to microbial diversity.
Emily Courtney is a Writer and Editor at Hyperbiotics and mom to two fun and active boys. Emily is passionate about natural wellness and helping others learn about the power of probiotics for vibrant health! For more ideas on how you can benefit from the power of probiotics and live healthier days, be sure to subscribe to our newsletter.