Fiber Fueled (2020) introduces you to your gut microbiome and its importance for your health. It explains how you can keep your microbiome healthy by eating a wide variety of plants.
Introduction: Discover the importance of a healthy microbiome for your own health.
Imagine for a moment that you’re in northern Canada on a clear night and you’re looking up at the Milky Way. You can see every single star. How many can you count? NASA says there are at least 100 billion of them. An amazing and wondrous sight, indeed.
Now, imagine instead of being in Canada, you’ve shrunk down to a size that enables you to fit inside your own colon. Okay, not exactly the nicest of places to be, but that’s where you are. If you were to count the microorganisms there, well, first of all, it might take you rather a long time, but if you managed it you’d reach a number somewhere in the region of 39 trillion!
Just to clarify, one trillion is 1,000 times one billion. So there are vastly more microorganisms in your colon than there are stars in the Milky Way.
And if you think that’s kind of mind-blowing, what about this? It’s possible to argue that only 10 percent of you is human and the other 90 percent is made up of microorganisms. So, actually, you’re more like a superorganism providing an ecosystem for microorganisms.
These facts and figures might be intriguing, but why do they matter? Well, in this summary to Dr. Bulsiewicz’s Fiber Fueled you’ll get to meet your gut microbiome, discover why it’s important for your health, and what you should be eating to keep it healthy.
Meet your gut microbiome
Whatever you think you know about the importance of your microbiome is probably only the tip of the iceberg. Research in the field is growing at an exponential rate with 12,900 papers published in the last five years – that’s 80 percent of all the papers published about the gut microbiome in the last 40 years. And in the last 15 years or so, we’ve gone from knowing about 200 species of bacteria in the human gut to 15,000. It’s believed that there may even be as many as 36,000 species.
So what exactly is your microbiome? Well, the collection of microorganisms living inside you which includes bacteria, viruses, fungi, parasites, and archaea, is usually referred to as the gut microbiota, and the term microbiome is reserved for its genetic makeup. Let’s look a little closer at each of the microbes.
Bacteria are single-celled organisms that most people associated with illness. It’s true that some are bad – E. coli, for example – but most of them are good for us.
Fungi, on the other hand, are multicellular. Just as with bacteria, some are bad and some are good. Bacteria and fungi often compete, so while one flourishes the other withers.
Viruses are simply particles of DNA or RNA. And yet again there are bad ones that cause illnesses like hepatitis B, HIV, and, indeed COVID-19, but there are also good ones that work to keep your bacteria in harmony.
Parasites in your microbiome are like thieves – they steal energy from you and try to remain undetected. Some, like worms that can grow to 80 feet long, are – thankfully – rare in the Western world but others, like Toxoplasma gondii currently infect 60 million Americans – again, thankfully, mostly asymptomatically.
And then there are the archaea, ancient organisms that have been around for billions of years. Not only are they found in your colon, but also in ocean rift vents and volcanoes. They’re incredibly resilient and, right now, barely understood at all.
Your own gut microbiota is quite unique and diverse. For example, it contains from 300 to over 1,000 of the bacteria species possible from the 36,000 that are thought to exist.
So what does your gut microbiota do and what happens when it goes wrong?
Your microbiota is critically important to your digestive function, allowing you to extract nutrients from your food. Your food is also the food of the microbes in your microbiota and they thrive on different things. Remove a food group completely and the microbes that live on that starve to death. Not only that, your food choices in any 24 hours affect the evolution of the next 50 microbe generations. Effectively, this gives you a particular set of microbes that’s as unique as your fingerprint.
The importance of your microbiota has a reach far beyond the colon. Think of it as a kind of command center for your health. It’s involved in your immunity, metabolism, hormonal balance, cognition, and gene expression. Things that happen in your body or brain can often be traced back to the work of your gut microbes.
Disharmony and a lack of balance in your gut is known as dysbiosis and can lead to a loss of diversity of species which, in turn, can lead to a greater proportion of microbes that cause inflammation. When the wall of your colon is no longer protected by good microbes, this can lead to what’s called bacterial endotoxin entering your bloodstream. This bacterial endotoxin is produced by the likes of E. coli and Salmonella. Although the resulting inflammation can be quite low-grade it can also lead to life-threatening sepsis and even organ failure. It’s also linked to autoimmune diseases, obesity, coronary artery disease, type-2 diabetes, Alzheimer’s, and many other diseases. Bad news indeed.
In the next section, we’ll look at some of the factors that can cause the balance of your microbiota to go awry.
Overfed, undernourished, and hyper-medicated
Kristen was one of Dr. B’s patients. Struggling with chronic abdominal pain and diarrhea for years, she was overweight, anxious, depressed, took antibiotics three or four times a year for sinus infections, and had migraines and polycystic ovary syndrome. She was taking “shed-loads” of medicines. She’d eliminated gluten and beans from her diet as she thought she had a sensitivity to them and had also tried following a Paleo diet. But nothing worked. She was now considering switching to a Keto diet to try and lose weight.
Kristen’s not alone. A massive 72 percent of Americans are overweight with 40 percent carrying an extra 14 kilos or more around their waists and hips. Alarmingly, 60 percent of Americans over the age of 19 are on prescription drugs and in the last 12 years, the number using five or more drugs has doubled. Life in the twenty-first century has led to us experiencing problems associated with being overfed, undernourished, and hyper-medicated. We’re simply destroying our gut and our health.
Dr. B sees many Kristens at his clinic – patients with irritable bowel syndrome, acid reflux, chronic diarrhea, abdominal pains, wind and bloating, and constipation in various combinations. Some are also experiencing side effects from the medications they’re taking. Others have a hormonal balance, have gained weight, have an autoimmune disease, have a mental illness, have heart problems, diabetes, or any one of a plethora of associated concerns. Many of these problems are associated with the patient’s lifestyle.
The use of prescription drugs – especially antibiotics – decimates our gut microbiota. For example, a five-day course of ciprofloxacin kills off around one-third of gut bacteria! Some of the bacteria species recover in just four weeks. Others don’t even reappear after six months. And with some drugs, the effect is even more evident: four years after taking them, the bacteria still haven’t recovered.
When it comes to diet, according to the US Department of Agriculture, an average American obtains approximately 32 percent of their calories from animal sources, 57 percent from processed plants, and a mere 11 percent from wholegrains, fruit, veg, nuts, and beans.
Diets that include high animal protein content are associated with increased numbers of the bad inflammatory microbes whereas plant protein actively encourages the good anti-inflammatory species and suppresses the destructive ones. Is it any wonder, then, that in the five regions of the world where people live longer than the rest of us, the populations have diets that are at least 90 percent plant-based with an emphasis on seasonal fruits, veg, beans, nuts, and wholegrains?
And we shouldn’t forget sugar and refined carbohydrates. A staggering 69 kilos of sugar are, on average, consumed by Americans and 4.5 kilos of highly refined grains every year. Most of the fiber has been stripped away from these which means they’re rapidly absorbed in the intestine rather than digested slowly. This leads to a loss in diversity of our gut microbes and a rise in carbohydrate-loving inflammatory bacteria.
When it comes to all the preservatives, additives, and colorants in processed food, would you be surprised to learn that they may be destroying our microbes, too? Many of them most certainly are, and the effects of a staggering 99 percent haven’t even been studied.
The solution to all of these problems? We need to get to the root cause of the problem not treat the symptoms. You’ve probably guessed it already: what we need to do is heal our guts.
Keeping your gut healthy
Would you be surprised to learn that if you want to heal your gut and keep it healthy you need to start with fiber? The reason is that fiber is amazingly good for your gut microbiota. In fact, it’s probably the most powerful solution to restoring the health of your microbiota. Right now, though, most people are completely fiber starved – less than 3 percent of Americans get their recommended minimum daily intake. That means 97 percent are walking around with a dietary-fiber deficiency!
Fiber is a complex carbohydrate that comes from plants. They have a monopoly on this food source. You’ve probably been taught that the fiber you eat goes in, and basically, comes back out again unchanged. In actual fact, that’s way too simplistic. Your microbiota contains more than 60,000 enzymes that are capable of processing fiber as opposed to your own measly 17 which can break down some complex carbs, but not fiber. And what happens when fiber is broken down is that short-chain fatty acids or SCFAs are released.
These SCFAs make your colon more acidic which very importantly prevents the growth of inflammatory bacteria. Additionally, the SCFAs suppress dangerous bacterial strains like E. Coli and Salmonella. Your dietary fiber feeds your healthy microbes, which produce more and more SCFAs in a virtuous circle.
So what can you do to alleviate your dietary fiber deficiency? A quick trip down to the health food store to pick up some of those fiber bars should do the trick, right? Well, perhaps unsurprisingly, no. What you really need to do for your gut microbiome to be healthy is to diversify your plant intake, or “eat the rainbow.” You should also aim for your diet to be at least 90 percent plant-based.
Dr. Rob Knight – or as Dr. B likes to call him, “the god of gut health” – found that for maximum gut microbial diversity, you should really be eating 30 different plants each week. That’s not as impossible as it might sound. The acronym F GOALS can help you remember what you need to eat. Each letter of the acronym represents a fiber-fueled food group.
F is for fruit and also for fermented foods. Don’t worry about the sugar in fruits – it’s not your enemy as it’s not processed, and besides, fruits are packed with vitamins, minerals, phytochemicals, and, of course, fiber. For fermented foods, try some sourdough bread, sauerkraut, tempeh, kimchi, miso, and kombucha.
G is for greens and wholegrains. Greens such as kale, spinach, arugula, bok choy, and romaine are packed with nutrients. And when it comes to grains, you can consider them as being the foundation of your healthy gut due to their high fiber content.
O is for Omega-3 super seeds such as flax, chia, and hemp. Both omega-3 and omega-6 are needed in your diet as your body can’t make them itself. But omega-6 is usually plentiful enough and the seeds and walnuts will provide you with the omega-3 you need.
A is for aromatics which include onions, garlic, shallots, and leeks – all very flavorsome and full of nutrients. Add in some nutrient-dense fresh herbs too, like basil and chives.
L is for legumes, which are both healthy and cheap. Another foundation for your healthy gut due to their high fiber content.
S is for sulforaphane which is found in cruciferous vegetables such as broccoli, sprouts, kale, cabbage, and cauliflower. Sulforaphane is known to protect us from some cancers, is a powerful antioxidant, and may also help with some other conditions such as Parkinson’s and Alzheimer’s. It’s also known to help with anxiety and depression amongst many other benefits.
And as a bonus, there are two more S’s. The first bonus S is for ’shrooms – mushrooms, which contain nutrients that are known to strengthen the immune system and help protect against cancer. In particular, eating one button mushroom per day reduces the risk of breast cancer by 64 percent. And the second bonus S is for seaweed which is high in fiber and contains nutrients not found in land plants.
You should also note that combining many plants can create a powerful synergistic effect. For instance, kale and lemon. Kale’s a great source of iron, but it’s what’s called “non-heme” and is less bioavailable than the iron you can get from meat. Although “heme-iron” from animals is more bioavailable, it’s also more inflammatory and associated with heart disease, colon cancer, and type-2 diabetes. Adding vitamin C from the lemon to the kale greatly increases absorption of the iron. The benefit to you is a source of iron without the increased risk of heart disease, colon cancer, and diabetes!
So by now you know some of the benefits of increasing the fiber in your diet and how you can do that, but here’s one final tip to ensure you maintain a healthy gut microbiota: share your microbes! Meet other people. Spend time with them. Shake their hands or give them a high five. And if you’re with your partner and the mood is right, share a kiss. Yes, it’s an expression of love, but what you’ll also be doing is exchanging 80 million microbes with each other!
Fiber is incredibly important in our diets, yet 97 percent of Americans have a fiber intake of less than the daily recommended amount. Addressing this shortfall has incredible health benefits for your gut microbiota and, as a consequence, also for you.
You can do this by “eating the rainbow” of fiber-fueled foods. Every day, you should aim to include something from each of the foods represented by the acronym F GOALS. As a quick reminder, those are fruit and fermented, greens and wholegrains, omega-3 super seeds, aromatics, legumes, and sulforaphane-rich cruciferous vegetables. And as a bonus, those two additional S’s, ’shrooms and seaweed.
And finally, to maintain a healthy microbiota don’t forget to share your microbes around: shake hands, give a high five, or kiss, it’s up to you.
About the author
Dr. Will Bulsiewicz, or Dr. B as he’s known, is an award-winning gastroenterologist not only for his clinical work but also for his research. He’s contributed to over 20 published scientific articles and has also cowritten a companion book to his New York Times best-seller Fiber Fueled, aptly named The Fiber Fueled Cookbook.
Health, Nutrition, Health, Nonfiction, Food, Science, Self Help, Cookbooks, Vegan, Personal Development, Diets, Weight Loss & Weight Control, Medicine, Gastroenterology, Fiber
Table of Contents
Author’s Note xi
Part I Knowledge Is Power
1 The Engine that Drives Human Health Isn’t Even Human 3
2 Twenty-First-Century Life: Overfed, Undernourished, and Hyper-medicated 29
3 The Fiber Solution: Short-Chain Fatty Acids and Postbiotics for the Win 49
Part II The Fiber Fueled Approach
4 Eat the Rainbow to Find Your Pot of Gold 73
5 Finding Your Plant Passion with a Sensitive Gut 95
6 Fermentation Nation Rising 117
7 Prebiotics, Probiotics, and Postbiotics 137
8 The Fiber Fueled Foods 151
Part III The Fiber Fueled Plan
9 Fiber Fueled 365: The Lifestyle 173
10 The Fiber Fueled 4 Weeks 201
The instant New York Times, USA Today, and Publisher’s Weekly bestseller
A bold new plant-based plan that challenges popular keto and paleo diets, from an award-winning gastroenterologist.
The benefits of restrictive diets like paleo and keto have been touted for more than a decade, but as renowned gastroenterologist Dr. Will Bulsiewicz, or “Dr. B,” illuminates in this groundbreaking book, the explosion of studies on the microbiome makes it abundantly clear that elimination diets are in fact hazardous to our health. What studies clearly now show—and what Dr. B preaches with his patients—is that gut health is the key to boosting our metabolism, balancing our hormones, and taming the inflammation that causes a host of diseases. And the scientifically proven way to fuel our guts is with dietary fiber from an abundant variety of colorful plants.
Forget about the fiber your grandmother used to take—the cutting-edge science on fiber is incredibly exciting. As Dr. B explains, fiber energizes our gut microbes to create powerhouse postbiotics called short-chain fatty acids (SCFAs) that are essential to our health. SCFAs are scientifically proven to promote weight loss, repair leaky gut, strengthen the microbiome, optimize the immune system, reduce food sensitivities, lower cholesterol, reverse type 2 diabetes, improve brain function, and even prevent cancer. Restrictive fad diets starve the gut of the critical fiber we need, weaken the microbes, and make our system vulnerable.
As a former junk-food junkie, Dr. B knows firsthand the power of fiber to dramatically transform our health. The good news is that our guts can be trained. Fiber-rich, real foods—with fruits, vegetables, whole grains, seeds, nuts, and legumes—start working quickly and maintain your long-term health, promote weight loss, and allow you to thrive and feel great from the inside out.
With a 28-day jumpstart program with menus and more than 65 recipes, along with essential advice on food sensitivities, Fiber Fueled offers the blueprint to start turbocharging your gut for lifelong health today.
“There’s no doubt that the key to good health lies in the gut — and in Fiber Fueled, Dr. Will Bulsiewicz delivers an authoritative and refreshingly clear picture on how to optimize gut health, informed by cutting edge science. Fiber Fueled lays out a path to improving gut health that’s accessible, inspiring, and most importantly, achievable. It’s time to wake up and harness the power of 39 trillion microbes in your gut: dive into Fiber Fueled and find out how.” –William W. Li, MD, New York Times bestselling author of Eat to Beat Disease, President and Medical Director, The Angiogenesis Foundation
“Finally a gastroenterologist who understands gut health and the microbiome. Dr. Bulsiewicz’s new book, Fiber Fueled, will set a new standard of care within the medical community and permit patients to take control of their health destiny without dangerous drugs.”—Joel Fuhrman, MD, New York Times bestselling author of Eat For Life
“Will is Dr. Fiber! Get on the fiber train and transform your health from the inside out, literally… Poop like a champ, build an immune system that is a fortress, and feed your brain premium grade fuel. Pick up a copy of Fiber Fueled today!”—Rip Esselstyn, New York Times bestselling author of The Engine 2 Diet
“Dr. B breaks down the science behind why eating more fiber can literally save your life – not to mention heal inflammation, help you lose weight, and end your digestive distress for good. Read this book and be a part of the Fiber Fueled Revolution!”—Robynne Chutkan, MD, FASGE, author, Gutbliss, The Microbiome Solution, & The Bloat Cure
“A timely and authoritative discussion of the overwhelming scientific evidence supporting the health benefits of a largely plant based diet…A must read for everybody still unconvinced about the best diet to stay healthy.”—Emeran A. Mayer, MD PhD, author, The Mind-Gut Connection, Distinguished Professor of Medicine, Physiology and Psychiatry, David Geffen School of Medicine at UCLA
“Dr. B brilliantly explains why gut health is so important and how to get there without drugs. By eating (and not eating) certain foods, a whole lot of ills are going to simply disappear — finally, relief!”—Kathy Freston, New York Times bestselling author of Clean Protein, The Lean, and Quantum Wellness
Video and Podcast
Read an Excerpt/PDF Preview
Leslie came into my office worn out and exasperated. She was thirty- six years old, but she felt like she was pushing eighty. She was overweight, a trend that started in her late twenties while taking the antibiotic minocycline for her acne. She struggled daily with fatigue, sluggishness, insomnia, and lack of motivation. Her skin was broken out, her hair was thinning, and she had persistent loose stools. On top of all this was her extensive list of medical ailments: irritable bowel, type 2 diabetes, hyperlipidemia, autoimmune thyroiditis, depression, and anxiety.
After seeing several other GI doctors, a chiropractor, a hormone specialist, and an expensive cash- only functional doctor, she was confused and frustrated by the conflicting recommendations. Here she was at thirty- six, on four different medications with ten supplements to boot. “This isn’t the life I envisioned for myself,” she told me on that first visit. “I’m way too young to be feeling this old.”
Much of her frustration stemmed from not knowing what to eat. What should have been simple had become so complicated. She had gone Paleo in her late twenties to combat weight gain and she soon progressed to the Whole 30. She felt better for a short time on those diets, but when the weight gain and fatigue slowly started to creep back in, she desperately searched for a new diet solution and tried eliminating phytates and lectins. She’d been gluten- free for almost ten years and by the time I saw her in my office, she had completely eliminated grains, legumes, dairy, and nightshades. Her diet now consisted mostly of arugula, avocado, grass- fed meat, and bone broth, with very little variation. At times she’d test herself with some beans or whole- wheat bread, but she’d experience gas and bloating, which the diet gurus she was following warned was proof of inflammation.
“It is maddening to follow all the experts’ recommendations religiously and do exactly as I’m told, only to feel worse than ever and see my weight fluctuate like a yo yo!” she exclaimed. With each progressive elimination, she’d see at most short- term improvement, only to slide back into the same exhaustive pattern. The last straw came when she tried the ketogenic diet to lose weight, but it just made her diarrhea worse and it was now a bigger problem than ever.
At this point in our conversation, she was physically slumped forward, elbows on her knees, staring at the ground, eyes welled up with tears. I pulled my chair closer to hers and leaned in so we were on the same eye level.
“Leslie, it’s going to be all right. We’re going to get you better.” She looked up, a glimmer of hope in her eye. “I totally get your frustration. This is the most confusing time in human history for people who just want to get better. Too many experts saying too many different things. I need you to trust me. If you’re with me, then this is rock bottom right here, right now. Today is a fresh start for you with a new approach that makes you feel better and restores the real version of yourself that has been missing these last few years.”
Over the following months, Leslie and I worked closely together to make some major changes. We took her off most of her supplements and slowly reintroduced diversity back into her diet. Foods that she had been told were off- limits were brought back at the right time, in the right amount. She began to really enjoy her food for the first time in years. The restrictive diet had been challenging, boring, and futile for her. She got rid of her bone broth and tapered down on her animal product consumption while increasing fruits, veggies, and even whole grains. Artificial sweeteners and processed foods stayed on the sideline. Beans came back on the menu! And while the process wasn’t always easy, we worked through it together.
Front and center in her new way of eating was fiber- rich plants— fruit, veggies, whole grains, beans, and legumes. Why fiber? Because as you’re about to learn in this book, fiber is the heart and soul of true gut healing, and true gut healing leads to better health in everything from your cardiovascular system to your brain health to your hormonal health. It’s really that powerful.
When Leslie emerged on the other side and settled into her new approach, she was beaming with energy. She was having fun experimenting with all the new foods that she’d previously eliminated. She now knew exactly which foods she was sensitive to and was able to include them in her diet on a regular basis by simply being careful with portion size. Twelve pounds had melted away. Meanwhile, getting Fiber Fueled reversed Leslie’s diabetes and dramatically dropped her cholesterol. She was able to reduce the dosage of her thyroid medication, and she was back to having normal bowel movements. Best of all, she felt like herself again: alive, optimistic, and excited for the possibilities ahead of her.
Getting Fiber Fueled can help you with whatever you’re struggling with, too, whether it’s weight gain, hormone imbalances, digestive issues, or you just want to feel better in your own skin. I know this because I’ve seen it in Leslie and in hundreds of my own patients. Now it’s your turn.
The Fiber Fueled program
Perhaps you’re one of the many Americans suffering with digestive issues: heartburn, abdominal pain, gas and bloating, diarrhea or constipation. I know there are at least seventy million of you out there because I personally published that statistic in Gastroenterology, the top American journal in my field, just a few years ago. Without question, gut health starts with the foods that you eat. Unfortunately much of the advice being offered by popular “experts” is dead wrong. I’ve grown tired of watching bone broth and grass- fed meat be touted as gut healing. There’s not a single study to support that, not even a crappy one. Instead of offering recommendations based on trends and pseudoscience, my program offers you a scientifically validated approach that will truly heal your gut by restoring order to your gut microbiome.
Do you have a sensitive stomach? Do you have trouble processing certain foods, like beans, broccoli, and gluten- containing grains? Food sensitivity has become a major issue worldwide, with an estimated 20 percent of the world’s population suffering from some form of food intolerance. I see it every single day in my clinic, and I’m going to share with you the strategy I’ve devised for my own patients to help identify exactly which foods they are sensitive to. I’ll also share my easy, step step plan for how to reintroduce those foods to eliminate the sensitivity and get back to enjoying them again.
If you’re one of the millions of Americans who have an autoimmune disease, then this book is for you, too. Seventy percent of the immune system resides in the gut, literally just a single layer of cells separating it from the microbiota. It’s hard to separate the two— they rise and fall together. By optimizing your gut microbes, we can help get your immune system back on track.Do you or someone you love have heart disease, cancer, a history of stroke, or Alzheimer’s disease? These are just a few of the dangerous and all- too- common conditions that can improve with this plan.
The Fiber Fueled approach doesn’t just benefit digestive disorders. In fact, this is literally the only diet plan that’s been scientifically proven to actually reverse heart disease.
Maybe you consider yourself pretty healthy and just want to stay that way. That’s the situation I’m in as well. I haven’t always been in great shape, but right now, by practicing what I preach, I feel fantastic. I’ve lost nearly fifty pounds, I’m back to my college weight, and I feel like I’ve actually reversed the aging process. There’s real science to support that. This is the only dietary approach shown to lengthen telomeres, which is the part of our cells that cause aging as they get shorter. Longer telomeres have been suggested to indicate slow aging and reduced risk of heart disease, cancer, Alzheimer’s, and Parkinson’s.
You’re going to learn in this book that you are one of a kind with a gut microbiome as unique as a fingerprint. So there is no one-size-fits-all when it comes to diet. Something that works for another person may not work for you, and that’s driven by the individual nature of your gut microbiome. But if you’ll treat me like your doctor, mentor, and lifestyle coach, I’ll walk you through a program that will be personalized and tailored to your unique needs and ultimately guide you to the vibrant health that you deserve.
This book is the consummation of everything I’ve learned about gut health during the two decades that I’ve been grinding to become the best doctor I can possibly be. With the Fiber Fueled 4 Weeks (see Chapter 10), I’ll show you how to use a healthy diet, lifestyle, and high- quality supplements to address the root cause of your problems. This isn’t just a treatment plan; it’s a way of life that will help you discover your healthiest self. Your symptoms will dissipate, your doctor will be shocked when your medicine ends up in the trash, and you’ll enjoy the vibrant health you’ve always wanted.