Is Fiber Wrecking Your Gut Health?

Research illustrates that not everyone benefits from fiber, and avoiding it could even be beneficial in healing. 

Fast Speeds Imagery/Shutterstock

Jennifer Scribner began a vegetarian lifestyle at age 16 after reading a book about how eating meat had detrimental effects on the planet, as well as individual health.

She followed the restrictive diet for 18 years—during which she experienced increasingly painful inflammation and deteriorating health—until eventually, she learned to listen to what her body was asking for—meat.

Ms. Scribner told The Epoch Times that she thought eating vegetarian was “a world-saving mission.”

“It didn’t work for my body, but I didn’t acknowledge that because nobody told me to listen to my body,“ she said. ”They told me to listen to what experts were saying.”

When Ms. Scribner lowered her dietary fiber by eating more meat, she noticed an immediate improvement in her energy and severe acne. For the first time in years, she felt fantastic. Now a functional nutrition therapy practitioner and GAPS (gut and psychology syndrome) practitioner, her experience was like onboarding for her business—Body Wisdom Nutrition.

For a subset of Americans, it seems that heaping more fiber into their diets in the name of health is often the culprit for feeling miserable and might even contribute to disease. New research is affirming previous findings that some people can’t digest fiber well, leading to a host of problems. Dietary experts say these people need a fiber reset so they can nurture a healthy community of microbes in their digestive tract capable of unlocking the health benefits of fiber.

The Fiber Food Bias

Fiber comes from plant-based foods such as beans, grains, peas, lentils, fruit, and vegetables. Eating high-fiber foods is associated with better digestion, lowered risk of heart disease, less constipation, and generally improved health—for most people.

Health authorities suggest that most Americans need more fiber in their diet, not less. Unfortunately, this can mislead certain people.

The U.S. Department of Agriculture’s MyPlate dietary guidelines suggest that more than half our diet should come from high-fiber foods such as fruits, vegetables, and grains, and many experts also advise people to eat 30 or more plants each week for better gut health. This loud-and-clear message tells Americans they need to eat more fiber. And for most people, it’s a message worth heeding.

Fiber’s Contribution to Health

There are two types of fiber: soluble and insoluble, depending on their biochemical makeup.

Soluble fiber slows digestion and is linked to the production of beneficial metabolites called short-chain fatty acids, which offer us health benefits that protect heart and kidney health, lower inflammation, and regulate the immune system—including protecting the body from diabetes, cancer, and obesity. Insoluble fiber adds bulk to digestion and modulates intestinal transit times.

Fiber is naturally found in a wide variety of foods, including seeds and nuts, but it’s also added to manufactured products. We need 25 to 35 grams of fiber daily, according to Harvard Medical, but we typically consume only 15 grams. Fiber plays a major role in regulating blood sugar and modulating appetite—important functions that can combat obesity.

Besides offering us better metabolic health, fiber has been linked to improved bowel movements and a more robust gut microbiome. The latter is vital because our community of microbes includes the bacteria essential to digest fiber. And it may be these bacteria that decide whether fiber ensures our health—or ruins it.

How Microbes Predict Our Fiber Response

The microbiome stands at the crux of the fiber debate. Some of fiber’s biggest fans acknowledge that sometimes it simply doesn’t sit well for some people, and the reason comes down to our microscopic bugs.

Dr. Will Bulsiewicz, a gastroenterologist and the author of “Fiber Fueled,” explained on a podcast that people with digestive issues often have trouble processing fiber because it can cause gas, bloating, flatulence, and abdominal comfort.

“My message to these people, that I want you to know, is that you’re struggling with the digestion of fiber because your gut has been damaged. These microbes—they’re struggling to keep up with what you’re asking them to do,” Dr. Bulsiewicz said.

The problem is most people experience damage to their gut microbiome because of a long list of chemical and other exposures that come with living in an industrialized world. Among them are antibiotics and other medications, glyphosate, antimicrobial hygiene products, alcohol, smoking, lack of sleep and exercise, artificial sweeteners, various food additives and emulsifiers, and chronic stress.

“Since so many people today have dysbiosis—or a disrupted microbiome—or very low flora, we tend to have a lot of issues digesting these fibers,” Ms. Scribner said.

Fiber’s Effect Remains Hard to Predict

A study published this year proved that fiber plays a highly individualized role in the body depending on each person’s microbiome. Although fiber seems to be generally beneficial in a wide variety of disease states, it’s unpredictable even for individual diseases.

Published in Microbiome, the study aimed to see how two forms of dietary fiber affect the microbiota of healthy subjects. The researchers recreated individual microbiomes through donor samples to conduct their tests in a lab setting. They found that inflammation was dependent on the context, meaning the microbiota composition was the driver for inflammatory bowel disease (IBD).

Fiber is a double-edged sword, the authors of the study pointed out, that can either promote or denigrate health depending on both the type of fiber eaten and the individuals’ microbiota makeup.

The study findings suggest a personalized approach: “IBD patients hosting a fiber-resistant microbiota should not refrain from consuming various soluble fibers, while patients with a fiber-sensitive microbiota should carefully consider fiber intake and fiber source as a central actor for disease management.”

The findings also offer credibility to an older study, published in 2012 in the World Journal of Gastroenterology, that examined cases of idiopathic constipation. Sixty-three subjects were asked to remove all fiber from their diet for two weeks and then reduce it afterward to a level they found acceptable. Symptoms were recorded at one month and six months after the dietary change, including rectal bleeding, bloating, abdominal pain, and difficulty evacuating stool.

“Patients who stopped or reduced dietary fiber had significant improvement in their symptoms while those who continued on a high fiber diet had no change,” the study authors wrote.

Fermented Food Over Fiber?

Another study compared fiber with fermented food to see which one was more beneficial for gut health, including improving microbial diversity and lowering inflammatory markers. Researchers anticipated that fiber would come out the winner, but that prediction was wrong.

Published in Cell in 2021, the study noted that eating fermented foods such as yogurt, kefir, kimchi, and other fermented vegetables, and kombucha tea increased microbial diversity—an effect that grew proportionally with servings.

Inflammatory markers improved in that group but did not change in the high-fiber group that ate nuts, whole grains, seeds, legumes, fruits, and vegetables. They also experienced no change in microbial diversity.

It makes sense that plants would be beneficial from many perspectives, including being able to bind to toxins such as heavy metals in the body, Ms. Scribner said. She added that eating more fiber is usually an upgrade, compared with the industrial food model that many Americans follow.

Sounding the Fiber Alarm

Figuring out whether fiber is an issue can be a relatively straightforward process. Ms. Scribner said she takes all fiber out of her clients’ diets if they are willing to try it for their digestive woes. Her goal is to slowly add it back in using a more intuitive and ancestral dietary philosophy that involves soaking, sprouting, and pre-fermenting grains.

Other times, she starts by removing grains only—depending on the client’s willingness and what dietary approaches they’ve already tried.

Of course, not everyone has an issue with fiber. Some people, however, need to try a counter-mainstream approach that flies in the face of the mainstream concerns about Americans’ lack of fiber.

Fiber, it seems, isn’t the universal health panacea some would suggest. Part of the issue stems from the quality of the fiber we eat.

Ms. Scribner said she is not against eating fiber but suggested that the source, preparation, and timing of eating fiber-based foods might be a better focus than a broad sweeping approach that homes in on daily amounts.

Adding Fiber Back to the Diet

When Ms. Scribner helps clients add fiber back to their diets, they consume high-quality fiber, such as locally grown, in-season plants rather than mass-produced crops treated with herbicides and pesticides and shipped all over the world.

“I think where the carnivore crowd gets it wrong is they eliminate all these things forever,” she said. “That doesn’t necessarily improve the microbiome enough to bring plants and/or grains back in in a digestible way so they can still maintain good health and bowel habits.”

Dr. William Davis, a cardiologist and author of several books, including “Super Gut,” agreed that restrictive diets are a big mistake in the long term.

“What you are doing is starving good microbes as well as bad,” he told The Epoch Times. “My way would be to restore the microbes that colonize the small intestine and produce bacteriocins, then reintroduce—after several weeks—those other foods. Almost always, you say, ‘Wow! I can eat anything now, and I don’t have bloating, diarrhea, abdominal pain, anxiety, panic attacks, all that stuff.’”

Bacteriocins are metabolites that lower the population of opportunistic pathogens causing dysbiosis, usually in cases of small intestinal bacterial overgrowth or Candida overgrowth. Allopathic and even some natural approaches might use antibiotics to wipe out the entire microbiome and start from scratch.

“It’s a modern situation,” Dr. Davis said of dysbiosis, “And unfortunately it gets treated in stupid ways—drugs, cleanses, food avoidance. Those are not solutions. Those are simply ways to reduce symptoms.”

And reducing those symptoms could lead to new ones if fiber is not reintroduced.

Very few Americans meet the dietary guideline for fiber, with an average shortfall of 50 percent, which professor Henry Thompson argued in a 2021 editorial in Nutrients increases the risk and cost of chronic diseases.

He wrote, “The highlighting of dietary fiber as a dietary component of public health concerns is warranted, even though fiber is not considered an essential nutrient.”

Ms. Scribner pairs fiber elimination with homemade yogurt or kefir to facilitate an environment that will naturally starve out the bad bugs.

“We don’t want to go for killing anything until maybe it’s needed—after we’ve built up a really robust flora—because the body wants to be healed and in functional working order,” she said.