When Fiber is Not Your Friend

America is a constipated nation…. If you pass small stools, you have to have large hospitals. – Denis Burkitt

Constipated? Bloated, swollen, and gassy? Foggy brain and feeling awful? Haven’t pooped in 6 days? Haven’t pooped in over a week?

The sun is shining but the fatigue makes you just want to stay in bed, forever? Eating the “perfect” diet but still feel like a bag of old potatoes?

I’ve been there.

Looking down at my swollen belly, filled with the most nutrient dense, organic, superfoods, trapped within my small intestines, I felt hopeless. With each passing day, the food continued fermenting, rotting, and releasing endotoxins in the process. I was poisoned from the inside out, known as autointoxication, with a foul mood to match.

The most common advice is to increase fiber. Nutritionists, gastroenterologists, colon hydrotherapists, functional doctors, all recommend loading up on even more fiber to get things moving. Just eat more whole grains, beans, nuts, seeds, fruits, and leafy greens, and the rest will take care of itself, they say. Over the years, epidemiological and animal studies have suggested that eating fiber functions like a ‘colonic broom’, binding to and diluting fecal carcinogens and secondary bile acids (that may promote tumors by increasing colonic cell proliferation or by mutagenesis) and reducing intestinal transit time, hence limiting colonic exposure to carcinogens and endotoxins.

Seeking smooth moves and bowel freedom, increasing my fiber intake is exactly what I did.

I loaded up on even more chia seeds, psyllium husks, ate bowls of kale salad the size of my bathtub, and consumed the majority of my protein from sprouted lentils, quinoa, beans, ancient grains, tempeh, and almond butter. With each bite, my belly swelled more, yet bowel movements remained elusive. I tried every healing diet, from GAPS, SCD, low FODMAP, low carb, fruitarian, juicetarian, zero carb carnivore, with only slight shifts or covering up certain symptoms, but never getting to the root cause.

While simply increasing fiber might work for some, regaining gut motility with those dealing with chronic constipation, SIBO, low thyroid function, and gut dysbiosis requires nuance, attention to details, and an understanding of exactly what fiber does in our system. “In practice, many patients with IBS complain of bloating with higher doses of natural fibre, likely due to bacterial fermentation producing short-chain fatty acids, increasing colonic gas and dystension, and hence, aggravating IBS symptoms,” and worsening their constipation.


What the “Experts” are Saying

According to the Academy of Nutrition and Dietetics, Americans average about 15 grams of fiber a day, but they recommend 25 grams for women, and 30 for men. Early research by Dr. Burkitt in the 60’s found that Ugandans that ate a high-fiber diet avoided the health complications associated with Americans and Europeans.

“In Africa, treating people who live largely off the land on vegetables they grow, I hardly ever saw cases of many of the most common diseases in the United States and England – including coronary heart disease, adult-onset diabetes, varicose veins, obesity, diverticulitis, appendicitis, gallstones, dental cavities, hemorrhoids, hiatal hernias and constipation. Western diets are so low on bulk and so dense in calories, that our intestines just don’t pass enough volume to remain healthy.”

The average transit time for people eating a high fiber diet averaged less than 24 hours, whereas the average Americans has a 48-96 hour transit time, allowing plenty of time for food particles to ferment and rot within us. Yikes!

But what else are these Ugandans doing that might contribute to abundant bowel movements and overall vitality?

Perhaps getting adequate sunlight, an appropriate dose of movement, exposure to beneficial soil-based microbes, living in community, away from the pollution, pharmaceuticals, vaccinations, smog, blue light, EMFs, and the cultural mayhem that characterizes city life had a health-inducing impact, as well.

What if the fiber had really little to do with it? What if the healthy lifestyle of the Ugandans studied acted as a halo effect, confounding the benefits we thought were due to fiber?

Although most gastroenterologists advise a high fiber diet, overall evidence suggests a need for a more critical look at the virtues of fiber. Individuals who consume more fiber might have other healthy lifestyle attributes, including managing their stressors effectively, prioritizing creativity, connection and play, feeling a sense of purpose in their work, sleeping deeply, and having a balanced gut microbiome in general.

Proponents of the carnivore diet, Like Dr. Paul Saladino and Zsofia Clemens, actually find that in some cases, removal of all dietary fiber clears up chronic constipation. Analogous to cars in a traffic jam, removing fiber allows the blockage to clear up. When things aren’t moving, the last thing you want to do is add more bulk to the jam.

When is less fiber a better option?

For some, a bacterial overgrowth in the small intestines combined with a very slow transit time gives ample opportunity for bacteria to feed upon the fibers we do ingest. Even with normal peristalsis–the waves of the intestines that squeeze our food along– the intestines can become so thick, inflamed, and filled with gas that they can’t squeeze the food along. If you’ve ever had poops the width of a pencil, suspect intestinal inflammation as the culprit.

A slow transit time combined with bacteria and fungal overgrowth where it shouldn’t be (e.g. SIBO/SIFO), and eating massive amounts of foods rich in insoluble fiber, like grains, beans, nuts, and certain fruits, then provides the perfect dessert for the bacteria and fungi within us. The result is excessive amounts of fermentation, gas, and endotoxin (by-products of bacterial action), slowing down transit even further, every time these bacteria feed. The more gas these critters produce, the harder it is to move the stool along, akin to an air bubble trapped in a flipped over glass. Relatedly, the buildup of endotoxin and the reabsorption of such toxins and hormones further burdens our digestive and detoxification organs, creating the perfect catch-22 of constipation, inflammation, lowered thyroid function, and systemic toxicity.

As a result, our SIBO worsens, we develop allergies to food, struggle to sleep, lose the ability to digest lactose and tolerate even minor stressors, and slowly develop nutrient deficiencies as our health declines. Yikes again!

So, what do we do? We have to eat, and most of us enjoy eating the same foods that the bacteria within us also love!

A reminder here is that not all fibers are created equal and that the terrain of our intestines is everything. Studies on fibers impact on digestive disorders and disease are not distinguishing between soluble and insoluble fibers, or how certain types of foods contain highly fermentable fibers and can make certain conditions worse. Soluble fibers absorb water in the intestines, swelling up and adding bulk to our stools. Soluble fibers are abundant in grains, apples, peas, and potatoes.

Conversely, insoluble fibers remain completely undigested as they pass through us, thus acting as a broom in the intestines. Insoluble fiber is abundant in foods like raw carrots, bamboo shoots, and mushrooms, and the peels of certain fruits and vegetables.

According to Dr. Ray Peat, “polysaccharides and oligosaccharides (which are abundant in certain plants), include many kinds of molecules that no human enzyme can break down, so they necessarily aren’t broken down for absorption until they encounter bacterial or fungal enzymes. In a well maintained digestive system, those organisms will live almost exclusively in the large intestine, leaving the length of the small intestine for the absorption of monosaccharides without fermentation. When digestive secretions are inadequate, and peristalsis is sluggish, bacteria and fungi can invade the small intestine, interfering with digestion and causing inflammation and toxic effects. Lactose malabsorption has been corrected just by correcting a deficiency of thyroid or progesterone…Sometimes having a daily carrot salad (grated, with salt, olive oil, and a few drops of vinegar) will stimulate (and disinfect) the small intestine enough to prevent fermentation.”

What happened in my gut?

I’ve experimented on myself with the carnivore diet and removing all fibers for three months to see if it could clear up my SIBO and some nasty autointoxication from plant-based foods. When it came time to reintroduce foods, carrots were the first I added back in.

To my amazement, they added just the right kind of bulk to sweep things along, and the chronic constipation that plagued me since my youthful years seemingly found a friendly solution. On the flip side, soluble fibers and certain sugars, such as those in apples and sweet potatoes, proved disastrous, feeding the overgrowth of bacteria in my upper intestines far too quickly.

When people ask me what they should be eating and what they should avoid, it really all comes back to the context of their digestive organs and the terrain of their microbes. For those with a balanced flora in their colon, a basically sterile small intestine, and moderately fast transit time, a very high fiber diet could work and actually improve transit time and the elimination of toxins. However, most people have some degree of bacterial imbalance, and even healthy foods start to trigger immune responses in their systems.

For those with bacterial overgrowth, dysbiosis, SIBO, SIFO, low thyroid function and generally sluggish digestion, less fiber might make more sense for the time being. Paying keen attention to how certain fibers and foods make you feel is essential to untangling foods that do and don’t work, as well as identifying foods that might be feeding, fermenting, and creating excess gas and irritation.

Some people can handle massive amounts of granola, oatmeal, and apples, no problem, while another might find huge improvements avoiding all fibers aside from a daily raw carrot or a serving of bamboo shoots, while they are pruning back their bacterial overgrowths and addressing the root causes of their sluggish digestion.

Experimentation is everything. Questioning sweeping health claims and testing what works for your unique system allows for greater understanding of what steps will lead towards optimal health. If you’d like help along the path of experimentation and weeding through the bushes, I’m here to help.

“All life is an experiment. The more experiments you make the better.” -Ralph Waldo Emerson


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