Discussions about diet and nutrition tend to focus on the big three macro-nutritients – fat, protein and carbs. However for many of us the macro-nutrient we really should be focusing on is fibre. Most people in the UK don’t get nearly enough dietary fibre, the recommended intake for adults is 30g per day, but the actual average intake is only 17g for women and 20g for men. This is very concerning as low levels of dietary fibre are strongly associated with a wide range of chronic health conditions including constipation, cardiovascular disease, bowel cancer, type 2 diabetes and diverticulitis. A diet low in fibre is almost inevitably lacking in vegetables and fruit and high in processed food,
The importance of fibre in our diets and it’s link with diseases of the bowel were first highlighted 50 years ago by Denis Burkett a doctor who spent 20 years living and working in Uganda. On his return he noticed that many bowel diseases that were increasingly common in the developed world were almost or totally unknown in rural Uganda. He published a paper in the Lancet ” Related Disease – Related cause ” which proposed that a diet low in fibre could be a cause of both benign and maignant bowel tumours. He went on to publish the international best-seller ” Don’t forget fibre in your diet ” which brought fibre into the mainstream. It alo lead to a sudden surge in popularity of All Bran, a cereal that looks and tastes like rabbit droppings.
Fibre can be broadly sub-divided into 3 different groups soluble, insoluble, and fermentable. However as long as you are eating a range of foods with plenty of vegetables, fruit and whole grains you shouldn’t have to worry to much about getting enough of each different group. The exception to this is people suffering from IBS where certain types of high fibre foods can trigger symptoms, particularly for individuals with IBS related diarrhea. The current recommendations for people in this group is to follow the FODMAP diet. FODMAP stands for Fermentable Oligo-, Di, Mono-saccharides and Polyols. These are a group of carbohydrates that are poorly digested in the small intestine and then enter the colon where they are broken down by gut bacteria and produce gas. High FODMAP containing foods include many grains and pulses and some fruits, so anyone trying to consume a high fibre diet may inadvertently be also including a lot of FODMAP’s in their daily diet.
I have seen a number of clients suffering from IBS type symptoms who have benefited greatly from reducing their fibre intake. When discussing the option of reducing fibre with a client I have to explain that eating a lot of fibre rich foods can put further stress on an already under-performing bowel by pushing large amounts of bulky insoluble fibre through the digestive system. Although a low fibre diet is not recommended as a long term dietary strategy, it does have a place in managing IBS flare ups and allowing the gut time to recover, before gradually re-introducing low FODMAP sources of fibre. It is also important for IBS suffers to investigate the psychological component of IBS, more on this here