Conventional wisdom has it that dietary fiber is essential and beneficial for our health. Whole foods like fruits and vegetables are rich in fiber, so it must be healthy, right?
Well, it’s not that simple.
Here’s an idea that flips the script; fiber is a proxy for eating less processed food. When people replace refined foods with whole foods, they almost always see improvements in their health. Naturally, they’ll be eating more fiber since fruits and vegetables are higher in fiber than processed foods. But we can’t necessarily attribute these improvements in health outcomes to the increase in fiber consumption.
Let’s look into this further with another somewhat controversial statement; there’s nothing inherently healthy or nutritious about fiber. Think about it for a second. Why would the equivalent of eating toilet paper be something healthy for humans? Fiber is a non-nutritive substance we can’t digest.
So why do we think it’s so great then? Surely there’s got to be something to it or it wouldn’t have been promoted so much for the last few decades. And there’s got to be studies to prove this, right? Well there’s a lot less data than you think, and some of it actually concludes the exact opposite.
First, let’s focus on the fact that those who emphasize eating whole foods do so by excluding junk food. When we decide to eliminate refined foods, we have to replace those calories with healthier alternatives. While at Sapien we prefer to replace most of these calories with a source of animal protein and fat, most people turn to a high fiber alternative as their main source of nutrition: fresh produce.
For the past few decades, fibrous fruits and vegetables have been touted as the gold standard of nutrition. As a result, observational studies that associate fiber consumption with lower morbidity and mortality rates are confounded by the healthy user bias.
Those who listen to their doctor’s advice to eat more produce are more likely to exercise and less likely to drink and smoke. These are more health-conscious people who engage in less risky behaviors than the average person, but observational studies conveniently ignore this phenomenon.
Since comparing health conscious vegetarians to the average person skews the data, several studies have looked at the risk of death amongst vegetarians and vegans compared to health-conscious omnivores One of these studies was the EPIC-Oxford Cohort with 64,234 participants (1).
This cohort study looked at the risk of death among vegetarians and their omnivorous, health-conscious peers. Despite the fact that the vegetarian diet is substantially higher in fiber than an omnivorous diet, this study found no difference in mortality between health-conscious omnivores and vegetarians. Both groups, however, had a 52% lower risk of death than the general population.
Fiber & Satiety
What’s going on when people lose weight and treat health conditions by prioritizing fiber-rich whole foods?
Well, whole foods are far more satiating than processed foods. Perhaps, it’s because they weren’t designed to be addictive by food scientists. Fruits and vegetables offer short term satiety because they’re low in calories relative to their volume. They fill up our stomach as a clean source of energy and nutrients compared to processed foods.
Processed foods like potato chips are easy to overeat because they contain virtually no fiber or volume relative to their calories. They tend to lack protein and other important micronutrients that can be found more readily in meat. Additionally, they’re packed with cheap, refined carbohydrates and industrial vegetable oils. It shouldn’t come as a surprise that these harmful ingredients are the very reason that processed foods are hyperpalatable and addictive.
Ultimately, long term satiety seems to come from a combination of dietary fat and protein rather than fiber. By definition, dietary fiber is plant bulk that our bodies cannot absorb or digest. We don’t break down fiber and extract nutrients from it like we do with fats and proteins.
The higher fiber content of some whole foods has led people to believe that fiber has benefits beyond its presence in whole foods. There’s no doubt that whole foods are healthier than any manufactured foods like cereal, granola bars, chips, pasta, or cookies. But it’s not because of their fiber content and adding fiber to processed foods doesn’t magically make them healthier.
All the benefits of fiber can be attributed to its presence in whole foods. Fibreless whole foods like meat and eggs aren’t any less healthy because of their low fiber content.
So you see, we have thought about this wrong the whole time. We thought that people were healthy because they ate a lot of fiber. It turns out it was the other way around - healthy people who have a plethora of other healthy behaviors and focus on whole foods tend to eat a lot of fiber. We’re sorry to say, there’s nothing special about fiber - it just means you’re eating whole foods, which is ALWAYS a good idea.
The History of Fiber
Humans knew how to eat long before they learned about the supposed benefits of fiber. Our ancestors definitely weren’t taking fiber supplements along with their meat heavy diets. It’s likely that they thrived on relatively low-fiber diets just like most of the world until Dr. Denis Burkitt endorsed fiber in the 1970s.
Piggybacking off of the work of the Ancel Keys, Dr. Burkitt concluded that a decrease in fiber consumption was to blame for the chronic diseases of the western world. Next, Dr. Burkitt set out to find evidence to prove his conclusion.
In the same way that Ancel Keys decided that saturated fat causes heart disease and ignored all evidence to the contrary, Dr. Burkitt decided that low-fiber diets caused modern chronic diseases before he even found evidence to support his claim. He observed native people eating high-fiber diets, producing large stools, and essentially just came to the conclusion that this was great based on his observations.
Dr. Burkitt began calling for an increase in fiber consumption which conveniently fit the low-fat dogma of the 1980s. The mainstream quickly took hold of his narrative without any real evidence. Low and behold, the food pyramid emerged as a trojan horse for disease.
The very western diseases that Keys and Burkitt had tried to prevent absolutely skyrocketed on a diet that prioritized fiber and restricted saturated fat and red meat. But hey, at least Americans were eating their fruits and vegetables.
In the 1990s, the Bristol Stool Chart was designed and lent even more credit to the high fiber narrative. Americans quickly learned that eating a bunch of fiber would maximize the size of their stool and increase the frequency of their bowel movements. Eating more indigestible and nutritionally devoid plant matter led them to excrete more waste. In other words, eating more waste led to larger and more frequent waste products.
Apparently, nobody considered eating more of the foods that our body could absorb with ease and less of the foods that our digestive tract could not absorb at all.
The Dark Side of Fiber
A 2012 study explored the effects of fiber intake on bloating, the frequency of bowel movements, and the straining of passing stools (2). The subjects of the study already had regular constipation and they were separated into a zero fiber, reduced fiber and high fiber group.
Those who reduced their fiber intake went from having a bowel movement every 4.19 days to one every 1.9 days. Those who cut their fiber intake to zero went from having one bowel movement every 3.75 days to one every day. Symptoms such as bloating and straining to pass stools were present in 100% of the patients in the high fiber group.
For the reduced fiber group, 31.3% of patients exhibited bloating, and 43.8% of them experienced straining to pass stools. In the zero fiber group, 0% of the patients experienced bloating or straining.
Pretty shocking, right? This is in direct opposition to what has been promoted for the last few decades. Clearly, increasing fiber intake is not the only way to manage digestive problems. Some studies have even shown that patients with chronic constipation may experience a worsening in symptoms when they increase their fiber intake (3).
When we replace fibrous whole foods, like fruits and vegetables, with fibreless whole foods like meat and eggs, our stools become smaller and easier to pass. This is an indication that we are using the nutrients in our food rather than accumulating bulk in our intestines. Consuming less of this bulky, useless plant matter leads to less bloating and more comfortable bowel movements. And no, minimizing fiber does not cause diarrhea.
With the emergence of the carnivore diet, thousands of people have lost weight and healed digestive issues eating zero fiber. And that’s just the start. People who have experienced debilitating autoimmune conditions their entire lives have found relief virtually overnight by switching to a diet composed of almost entirely meat.
A quick google search of Mikhaila Peterson will reveal her incredible journey from crippling autoimmune conditions to thriving health on an all-meat diet. Since eliminating fiber from our diet can have benefits, it’s worth exploring the dark side of fiber.
In Konstantin Monastrysky’s book, The Fiber Menace, he argues that fiber can wreak havoc on our digestive tract, worsen constipation, and even impede our sexual health. He tells the story of Dr. John Kellogg who thought constipation was to blame for the human sex drive.
Kellogg’s bizarre theory and belief in chastity is not what brought him to fame. Instead, his company made a fortune off of disguising breakfast cereals as health foods. These cereals were developed from livestock feed and were designed to have a laxative effect. The comfort of bowel movements was of no concern to Dr. Kellogg.
Healthy Low-Fiber Diets
One argument from plant-based enthusiasts suggests that one of the reasons we should eat fiber is that our colon requires butyrate to function properly. Butyrate is a short chain fatty acid that is one of the byproducts of fiber fermentation. It supports digestive and immune health by providing the energy our gut lining needs to function and regenerate.
The problem with this argument is that in the absence of dietary fiber our body can produce butyrate from amino acids and ketone bodies. Collagen and the "bits & pieces" of the animal provide the same short chain fatty acids (SCFAs) as plant fibers do. A diet consisting largely of meat will be replete with amino acids and produce ketones if it is relatively low in carbohydrates. In other words, we can get the benefits of butyrate without consuming wasted, indigestible plant material.
Even though most of the benefits of fiber have been overstated, it can still provide some value to our diet. Just because some people cannot tolerate it does not mean that it is harmful for everyone. There's also many sources of fiber that people find easier to consume and come with less of the "downsides" like sauerkraut, mushrooms, or avocado.
From an ancestral perspective, humans have always incorporated some plant foods in their diet. Even in the arctic, depending on the season, humans sought sources of plant foods. When humans could not forage, they would trade for plant foods. They would even eat the stomach content of animals when given the chance. As a result, we’ve adapted to tolerate some fiber.
Now, we’re not suggesting that our ancestors decided to eat a bunch of leaves when they failed on a hunt. They most certainly were not going out of their way to eat a pile of kale for some obscure health benefit that they heard about on the internet. But, at times, they definitely sought out fibrous fruits and tubers in addition to their meat-based diets.
We could spend all day speculating on why they included these plant foods, but ultimately it was for energy and nutrients – not some supposed benefits of fiber. They likely aimed for foods that had low fiber per calorie since we cannot efficiently extract energy and nutrients from plants that are encased in fiber. If we relied on leafy greens for our energy, we would need to consume dangerous amounts. That’s why we should rely on more bioavailable sources of energy and nutrients like fatty cuts of red meat.
The Fiber Verdict
If fiber was truly the superfood that was going to save us from the explosion in chronic diseases, then toilet paper companies would have been selling their rolls in the health food aisles. Fortunately, our bodies demand more bioavailable forms of nutrients like those found in quality animal products. And these happen to contain no fiber.
The paradigm that has propped up fiber will change as evidence continues to vindicate zero-fiber whole foods like meat, eggs, and dairy products. We need to fight for a food system that favors quality animal products over fiber-rich processed foods or even monocropped produce from the fields of Monsanto.
One thing is for sure though. Fiber isn’t the miracle food that the media and scientists have made it out to be.
We’ve been led to believe that fiber had benefits beyond being associated with health. It’s only associated with health because of its presence in most whole foods. Again, we want to reiterate our assertion that fiber is merely a proxy for people eating whole food diets. We should keep in mind the basic scientific principle that correlation doesn’t equal causation, even if it fits our narrative.
As it turns out, we can thrive eating whole foods whether they contain fiber or not. For decades, health-conscious people have been eating more fiber than the average person. But it wasn’t the fiber that made them healthy, it was the lack of processed food in their diet.
Processed foods are the real culprit here. Fiber isn’t the problem, but it’s certainly not the solution. Eating some fiber in the form of produce might be a tool for improving your health, but avoiding processed foods is the most powerful tool for living a long, healthy life.
Fiber has the nutritional value of toilet paper. Why has it been labeled a health food?