The Rise of Fibre Consumption
In the realm of dietary trends, the once-popular notion of “proteinmaxxing” has been eclipsed by a burgeoning focus on fibre intake. Since the summer of 2025, Instagram has recorded over 10,000 posts tagged with #Fibermaxxing and related fibre hashtags, indicating an enthusiasm that shows no signs of waning.
This new trend serves as a reminder of the historical shifts in human diets. With the advent of agriculture around 12,000 years ago and the introduction of modern food processing techniques approximately 200 years ago, many individuals have drastically reduced their fibre consumption, particularly in developed nations. Research indicates that around 95% of Americans do not meet their recommended fibre intake, a situation mirrored in various parts of the world. This substantial dietary shift has had a detrimental impact on our microbiome—the vast array of microbes residing within our digestive systems—leading to troubling health repercussions.
Jens Walter, a microbiome scientist at University College Cork in Ireland, states, “The alteration of our microbiome is linked to an increase in chronic diseases.” Walter is part of a community of microbiologists, nutritionists, and researchers investigating the biological effects of fibre on gut bacteria, amassing growing evidence that fibre—and the microbes it nourishes—provides protection against conditions such as inflammatory bowel disease, colorectal cancer, and diabetes. These findings not only highlight the importance of fibre but also pave the way for innovative solutions, potentially leading to personalised fibre recipes in the future.
Understanding Different Types of Fibre
Dietary fibre comprises various carbohydrates derived from plant foods, which, unlike starches and sugars, cannot be digested by the human body. Nevertheless, they offer numerous benefits in alternative ways.
Traditionally, nutrition scientists categorised fibre primarily as either soluble (like fruit pectin) or insoluble (such as wheat bran) based on its ability to dissolve in water. However, modern classifications have become more nuanced, considering factors such as bulking capacity (the ability of fibre to retain water and increase stool size), fermentability (how easily gut microbes break it down), and viscosity (its tendency to thicken into a gel in the digestive system). Foods rich in various types of fibre include beans, legumes, nuts, seeds, fruits, vegetables, and whole grains.
The exploration of the fibre-health relationship dates back at least to the 19th century when several surgeons, doctors, and researchers began examining diet as a determinant of disease. While many did not focus specifically on fibre, they noted disease patterns among populations adhering to low-residue or low-fibre diets. In 1949, two scientists found that rats on a low-fibre plant diet began developing diverticula—pouches in the colon that can become inflamed and infected—and that introducing plant fibre, via psyllium seed husks, prevented this condition.
Historical Insights on Fibre and Health
In the following decades, researchers began to posit that the increasing absence of fibre in diets, particularly in the wake of the Industrial Revolution, contributed to rising illness rates. UK surgeons Neil Painter and Denis Burkitt published a paper in 1971 labelling diverticular disease as “civilisation’s deficiency disease” after observing low rates of this condition in certain African populations that maintained a fibre-rich diet.
Burkitt, Painter, and a colleague later conducted a study comparing stool size and transit time in individuals from the UK, South Africa, Uganda, and India. They found that people in rural Uganda and South Africa—who consumed less processed and more fibre-rich diets—produced heavier, softer stools that passed through their intestines more quickly than their urban and European counterparts. Their analysis of records from over 200 hospitals across more than 20 countries revealed that appendicitis, colon cancer, and diverticular disease were rare in non-Western developing countries, while rates had been rising in places like England since 1870. Burkitt, who later became known as “the fibre man,” hypothesised that difficulties in evacuation were to blame, giving rise to the fibre hypothesis.
Burkitt and his contemporaries speculated about the impact of fibre on gut flora. In 1977, researchers at Virginia Tech published a study on various species of colon bacteria that fermented dietary fibres, a process that provided essential carbon and energy for the bacteria. They discovered that this fibre digestion produced short-chain fatty acids that enter the bloodstream. Thus, while we cannot digest fibre ourselves, we benefit from it through our microbes.
Fibre’s Role in Digestive Health
Today, researchers have a deeper understanding of the fibre-health connection. They know that fibre adds bulk to stools, facilitating their passage through the digestive system and enhancing feelings of satiety after meals. Particularly, viscous fibre binds to bile acids, lowering cholesterol, slowing nutrient absorption, and improving blood sugar and lipid levels.
Moreover, the effects of fibre on gut microbes, which digest it for sustenance, are significant. Mahesh Desai, a microbiologist at the Luxembourg Institute of Health, states, “Fibre is indeed one of the dietary components that may have the most substantial impact on the microbiome.” Research has begun to elucidate how these gut microbes influence our health, especially concerning inflammation—a known contributing factor to diseases such as colon cancer, heart disease, and diabetes.
Investigating the Microbiome
Research in this area often involves collecting data on individuals’ diets and analysing their microbiomes and health parameters. In a 2021 study, for instance, epidemiologist Wenjie Ma from Massachusetts General Hospital and colleagues collected stool samples from over 300 men whose diets had been monitored over the long term.
The team analysed the DNA from these samples to identify the microbes present, as well as the RNA produced by these microbes to determine metabolic activity. They also examined participants’ blood levels of C-reactive protein, which is closely linked to chronic inflammation.
Findings revealed that higher fibre intake, particularly from fruits, appeared to enhance the gut microbiome’s ability to digest fibre and altered its composition towards species associated with anti-inflammatory effects. Increased fibre consumption was also linked to lower blood levels of C-reactive protein in many cases.
Personalised Nutrition and the Future
However, the beneficial effects of fibre on C-reactive protein were not observed in participants whose intestines contained a specific microbe, for reasons that remain unclear. This example, Ma asserts, suggests that not all intestines respond uniformly, indicating that nutritional advice may one day be tailored to individual needs.
If microbes interact with fibre to reduce inflammation, how does this occur? Part of the effect seems to stem from the short-chain fatty acids (acetate, butyrate, propionate) produced during fibre digestion. These short-chain fatty acids interact with immune cells in our intestines, reducing the production of pro-inflammatory molecules while promoting the creation of anti-inflammatory ones. For instance, a 2020 study on mice found that butyrate encourages the production of a protein generated by immune cells, known as IL-22, which combats intestinal inflammation.
The Protective Role of Short-Chain Fatty Acids
Aligned with this relationship, numerous studies have detected low levels of key short-chain fatty acids produced by the microbiome in individuals with septic shock, arthritis, multiple sclerosis, and colorectal cancer—all conditions associated with inflammation. Much of the impact of these short-chain fatty acids seems linked to the protection of the intestinal lining, a robust mucosal barrier safeguarding intestinal walls from abrasion and preventing pathogenic microbes from breaching it.
Desai investigated the effects of fibre on this barrier in an experiment involving groups of mice. The animals’ gut flora was replaced with human microbiomes created in the lab, and they were fed either a fibre-rich or a fibre-deficient diet. With their primary energy source restricted, the bacteria from the low-fibre diet resorted to consuming the mucus lining the colon, compromising the organ’s resistance to invaders.
Following this, scientists infected these mice with a rodent-specific bacterial pathogen. “This caused significant issues for the host,” he notes—the animals developed severe and sometimes lethal cases of colitis, a grave inflammation of the colon. In further experiments, Desai discovered that fibre-deficient mice were more susceptible to inflammatory bowel disease and food allergies compared to those receiving adequate fibre.
Fibre’s Impact on Weight Management
Nathalie Delzenne, a pharmaceutical researcher at KU Leuven in Belgium, is exploring another potential benefit of fibre consumption: maintaining a healthy weight. Strong evidence suggests that certain compositions of gut microbiomes are linked to metabolic issues such as obesity and prediabetes, possibly due to lower butyrate production. Some fibres, like inulin found in foods such as asparagus, bananas, chicory root, wheat, garlic, and onions, appear to boost levels of gut bacteria that produce butyrate and, in both rodents and humans, create an effect akin to that of Ozempic when consumed. This effect stimulates the production of the satiety hormone GLP-1, leading to reduced hunger and promoting weight loss, says Delzenne.
Regarding other beneficial effects of inulin, a 2025 study revealed that mice fed both high-fructose corn syrup and a diet rich in inulin exhibited higher concentrations of gut bacteria that break down fructose. When inulin was subsequently administered to