Fibre: When too much of a good thing hurts your gut

For decades, fibre has been one of the quiet heroes of healthy eating. It keeps the bowel moving, helps prevent constipation and feeds the uncountable bacteria living in the gut. Now, social media has given fibre a new identity. The trend known as “fibremaxxing” is encouraging people to dramatically increase their fibre intake, sometimes to more than 50 grammes a day in the belief that more fibre automatically means better health.

But the  gut may not always agree. The trend is rooted in a legitimate concern. Many people do not consume enough fibre, particularly as diets increasingly shift towards highly processed foods. In Kenya, however, traditional foods such as beans, green grams, peas, vegetables, fruits, whole maize, millet and sorghum offer excellent sources of dietary fibre. For many people, improving fibre intake may therefore be less about buying expensive supplements and more about eating a wider variety of whole and minimally processed foods. Fibre is important because, unlike sugars and starches, it is not digested and absorbed in the small intestine.

Instead, it travels to the large intestine, where some types are fermented by gut bacteria. In the process, these bacteria produce short-chain fatty acids, including butyrate, which is believed to support the health of the colon and may have anti-inflammatory effects. Other types of fibre absorb water and add bulk to stool, making bowel movements easier and helping to prevent constipation. A diet rich in fibre has also been associated with a lower risk of several chronic diseases, including colorectal cancer. Fibre can also help people feel fuller for longer, which may support healthy weight management. Soluble fibre slows digestion and the absorption of some nutrients, helping to prevent sharp rises and falls in blood sugar.

But the message that “more is always better” can be misleading. A sudden and dramatic increase in fibre can leave some people with bloating, excessive gas, abdominal cramps and diarrhoea. For people with sensitive digestive systems or irritable bowel syndrome (IBS), certain types of fibre may make symptoms worse. This is particularly true of some fermentable carbohydrates known as FODMAPs, which can be difficult for some people to absorb. Fibre is also not one single substance. Soluble fibre absorbs water and slows digestion. Insoluble fibre adds bulk and helps move waste through the digestive tract. Fermentable fibre, meanwhile, provides food for gut bacteria. The body needs a balance of these different types.

The danger of fibremaxxing is that people may become focused on hitting an extreme daily target rather than eating a varied diet. Someone chasing more than 50g of fibre a day may rely heavily on a few high-fibre cereals, foods or supplements while missing out on the diversity of nutrients found in a broad range of whole foods. For most people, the better strategy is gradual change. Add more vegetables to meals. Eat fruits regularly. Choose whole grains where possible. Include traditional fibre-rich foods such as beans, green grams and peas. Increasing fibre slowly allows the gut to adjust. Drinking enough water is also important because fibre needs fluid to work effectively. Without adequate fluids, increasing fibre can sometimes worsen constipation rather than relieve it.

The fibremaxxing trend is part of a larger social media obsession with “cleansing” and “resetting” the gut. Juice cleanses, detox teas, laxatives, extreme elimination diets and even enemas are often promoted as quick solutions for digestive problems. But the digestive system does not need dramatic resets. Some of these practices can cause dehydration, deprive the body of essential nutrients or disturb the natural balance of the gut microbiome. Extreme elimination diets can also reduce the variety of foods in a person’s diet and potentially affect the diversity of beneficial bacteria that support digestion. The gut is a complex ecosystem.

It contains trillions of microorganisms that interact with the foods we eat and with one another. Supporting this system is therefore not about dramatically increasing one nutrient or eliminating entire food groups without medical guidance. It is about consistency and variety. A person experiencing persistent bloating, diarrhoea, constipation or abdominal pain should also not simply assume that the problem is caused by a lack of fibre.

Such symptoms may have several causes and may require medical assessment. For people with IBS or other digestive conditions, dietary changes may need to be individualized. What improves symptoms for one person may worsen them for another. Fibre remains an essential part of a healthy diet. Most people would benefit from eating more fibre-rich whole foods, particularly vegetables, fruits, legumes and whole grains. But the goal should not be to consume as much as possible. A Kenyan diet already offers many affordable sources of fibre. A plate containing beans or green grams, vegetables and a whole-grain staple can provide a more balanced approach than relying on expensive fibre powders or chasing extreme targets promoted online.

The key is to increase fibre gradually, drink enough fluids and eat a variety of foods. The gut thrives on variety, consistency and balance, not quick fixes or dramatic dietary overhauls. Fibremaxxing may have started as a well-intentioned attempt to improve health. But like many viral wellness trends, it risks reducing a complex subject to a simple formula: more is better. The reality is more nuanced. The healthiest approach to fibre is not to consume as much as possible, but to get enough from a varied, balanced diet that supports the entire body, not just the gut.