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Don't forget the fibre - for more reasons than one

Sara FL Kirk
PhD RD
Principal Research Fellow
Nutritional Epidemiology Group
University of Leeds.

A high intake of fibre has long been known to prevent constipation by bulking stool and reducing gastrointestinal transit time.(1) Yet, average fibre intakes in the UK fall well short of the recommended levels of 18g per day, at 15.2g for men but only 12.6g for women.(2) It has been estimated that constipation affects a quarter of the population at some time, causing considerable discomfort and distress.(3) Consider this, along with the estimated £43m spent on prescribing laxatives in the UK last year, and we can see that constipation costs.(4)
Fibre is not just an effective means of relieving constipation - it has other important benefits too. It is filling, thereby preventing hunger,(5) which is increasingly important given that overweight and obesity currently affect well over half the population.(6) There is increasing evidence that some types of fibre-containing foods can promote the colonisation of the gut by good bacteria,(7) and although the effect is modest, soluble fibre can also help to lower total and low-density lipoprotein cholesterol,(8) factors that are important in the aetiology of heart disease and type 2 diabetes. With all this evidence, why are average fibre intakes so low in the UK? Fibre is primarily found in wholegrain cereals, pulses, fruits and vegetables. As a society we are moving further towards a "convenience culture", relying on processed foods that are quick and easy to prepare, but which often tend to be higher in fat and lower in fibre than freshly prepared alternatives. High-fibre foods such as pulses, brown rice and wholewheat pasta all take time to prepare, yet there are several notable exceptions. Fruits, vegetables, wholemeal bread and high-fibre breakfast cereals are the ultimate convenience foods - just peel and chop, slap in a filling or pour on the milk and you have a healthy, high-fibre meal or snack in no time.
It may be a few years old now, but an interesting study from Australia looked at the effect of promoting an increased consumption of wholemeal bread in the elderly on subsequent laxative sales.(9) Three towns were selected for the intervention. One acted as a control, while in the other two a Community Organisation Strategy (COS), involving a campaign to promote bread consumption using the media, local advertising and a reduction in the price of bread, was compared with a Patient Education Strategy (PES) through local doctors to the target patients - people aged over 55 years. The COS used the wonderful slogan: "Bread: it's a great way to go" and resulted in a 60% increase in bread sales and a 60% fall in laxative sales! So, increasing fibre intake really can be a simple and effective strategy, with benefits far greater than the relief of constipation alone. This is a message that needs to be conveyed if we are to achieve an increase in average fibre intakes and have an impact on the nation's future health.

References

  1. Council on Scientific Affairs. Dietary fiber and health. JAMA 1989;262:542-6.
  2. Henderson L, Gregory J, Irving K. The national diet and nutrition survey: adults aged 19 to 64 years. Volume 2: energy, protein, carbohydrate, fat and alcohol intake. London: The Stationery Office; 2003.
  3. Kamm MA. Constipation and its management. BMJ 2003;327:459-60.
  4. Department of Health. Prescription cost analysis: England 2003. London: DH; 2003. Available from URL: http://www.publications. doh.gov.uk/stats/pca2003.xls (accessed 30 September 2004).
  5. Sparti A, Milon H, Di Vetta V, et al. Effects of diets high or low in ­unavailable and slowly digestible ­carbohydrates on the pattern of 24-h substrate oxidation and feelings of hunger in humans.Am J Clin Nutr 2000;72:1461-8.
  6. Department of Health. Health Survey for England 2002. London: DH; 2003. Available from URL: http://www.publications.doh.gov.uk/stats/trends1.htm (accessed 30 September 2004).
  7. Bengmark S. Immunonutrition: role of biosurfactants, fiber and probiotic bacteria. Nutrition 1998;14:585-94.
  8. Brown L, Rosner B, Willett W, Sacks F. Cholesterol-lowering effects of dietary fiber: a meta-analysis.Am J Clin Nutr 1999;69;30-42.
  9. Eggar G, Wolfenden K, Pares J, Mowbray G. "Bread: it's a great way to go": increasing bread consumption decreases laxative sales in an elderly community. Med J Aust 1991;155:820-1.