The effects of too much fibre in the diet

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Fibre is often a forgotten nutrient in many Britons' diets in modern mealtimes day. According to the National Health Service (NHS), on average most British people ate 20% less than the recommended 18 grammes a day. A diet that is high in fibre may help prevent heart disease and diabetes and may also lower your cholesterol levels if they are high. If you don't eat enough fibre, you should try to eat more, but also be aware of the side effects that too much fibre can have.

Short-term side effects

You can experience immediate side effects if you dramatically increase your fibre consumption. This is especially true if you have been eating a diet that was alerady low or nearly void of dietary fibre. Short-term side effects from a sudden increase in fibre include cramping, diarrhoea and intestinal gas. Gradually increasing your fibre intake over a period of 6 to 8 weeks will help you avoid these gastrointestinal short-term effects. However, even a gradual increase may cause some people stomach problems. If you have tried to gradually increase your dietary fibre intake and are still experiencing stomach problems, consult your doctor.


Drinking water while consuming a high-fibre diet is important. Drink no less than eight 235 ml (8 oz) glasses of water to prevent dehydration. Drinking water may help alleviate or prevent some of the short-term gastrointestinal side effects of increasing your fibre intake. Insoluble fibre is a type of fibre that your body cannot absorb or digest. Insoluble fibre is the type of fibre responsible for softening stools and preventing constipation. This is only possible if you are drinking enough fluid, however.

Prevention of nutrient absorption

Excess fibre intake can also potentially prevent your body from absorbing vitamins and minerals that are essential for your health. Excess fibre can "bind to certain essential minerals and cause them to be eliminated instead of absorbed into the bloodstream." Calcium, zinc, magnesium and iron are particularly vulnerable to this. However, this is not likely to happen if you are consuming high levels of fibre from solid foods such as beans, whole grains and nuts. Dietary fibre supplements are generally responsible for this condition. Consult your GP before you purchase a dietary fibre supplement.


While the side effects of fibre are concerning, they are also preventable. A diet high in fibre is much preferable to a diet that is low in fibre. A diet high in fibre can help you maintain your weight, prevent constipation and lower your risk of cardiovascular disease. Many Britons who eat a low-carbohydrate diet instead of a balanced diet tend to have inadequate fibre intake. Get fibre from a variety of foods including cereals, dried beans, fruits, vegetables and whole grains. Gradual intake accompanied by adequate amounts of water is recommended. While fibre can hinder mineral absorption, most high-fibre foods are rich in minerals, and thus, this side effect should not overly concern you.

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