Necessity of Dietary Fibre

Fibres are carbohydrates found in plants that cannot be digested by humans. Despite their indigestibility, they are often named as an essential component of a balanced diet. One of their purported benefits is helping with improving constipation. The main reasoning for this is that fibre is said to increase stool weight and increase water retention, resulting in softer stool that is easier to pass.

Despite this claim being very widespread, scientific evidence supporting it is very rare.

In one study by Ho et al., 63 patients who had been suffering from constipation, bloating and rectal bleeding were instructed to eliminate fibre from their diets for 2 weeks, including things such as unpolished rice, whole bread, vegetables and fruits. Furthermore, they were instructed to avoid taking laxatives and asked to maintain their carbohydrate and protein consumption. After the initial 2-week period they were then to maintain as low a dietary fibre intake as they were comfortable with for 6 months.

The patients generally fell into one of three camps, either retaining a zero-fibre diet, staying on a reduced fibre diet, or returning to a high fibre diet.

If fibre was truly important in avoiding constipation, it would be expected that the no-fibre group would show the worst results, whilst those that went on a high fibre diet should show the best results.

However, the results were the exact opposite. 41 patients had chosen to stay on a zero-fibre diet and all of them reported complete elimination of constipation and any related symptoms. Of the 16 people of those that ended on a reduced fibre diet, 12 reported constipation. Finally, all 6 patients that went on a high-fibre diet reported constipation.

The results of the study completely contradict the prevailing mainstream narrative that fibre is essential to fending off constipation and suggest that the polar opposite is true. Fibre seems to be one of the main drivers of constipation and reducing fibre consumption or entirely abstaining from fibre seems to be able to eliminate constipation.

Ho, K. S., Tan, C. Y., Mohd Daud, M. A., & Seow-Choen, F. (2012). Stopping or reducing dietary fiber intake reduces constipation and its associated symptoms. World journal of gastroenterology, 18(33), 4593–4596. 10.3748/wjg.v18.i33.4593.