Two review papers(1,2) have recently been published in the journal ‘Nutrition in Clinical Practice’ which look at the therapeutic approaches to dealing with irritable bowel syndrome (IBS). They cover everything from cognitive behaviour therapy and hypnosis to diet and nutrition. The papers are timely, this is a topic I am often asked about and have decided to spend the next few posts covering various nutritional aspects of IBS.
IBS describes a combination of symptoms including constipation, diarrhoea, abdominal pain/discomfort, nausea and vomiting, feelings of fullness, gas and bloating. Sufferers are often embarrassed by the condition which generally develops in individuals between the ages of 20 and 30 and affects around 20% of the population. IBS also appears to be more common in women than men.
The causes of this uncomfortable condition are unclear. However, an imbalance in intestinal bacteria is frequently implicated. Often IBS develops after a bout of gasteroenteritis or repeat courses of antibiotics (which kill off the vast majority of intestinal bacteria). The bacteria in the digestive system of individuals suffering from IBS seems to be different to healthy people with fewer ‘beneficial/friendly’ bacteria such as Bifidobacteria and Lactobacilli being present in those with IBS.
Up to about 30 years ago it was a common misperception that the major functions of the large intestine (colon) was simply water re-absorption and storage of waste matter. The colon is now recognised as an important organ due to the number of bacteria present (well over 10million bacteria are present in the colon per g of contents!). These bacteria produce compounds, which can have beneficial/positive, neutral or damaging influences on the body. Age, stress, antibiotics, the environment and diet can all affect the type of bacteria present in our digestive system. A healthy diet may help boost the number of the friendly bacteria and hence decrease the incidence of infective disorders of the gastrointestinal tract and boost natural resistance against them.
The knowledge that specific species of bacteria may be of benefit to our health, especially Lactobacilli and Bifidobacteria, led to the development of probiotics, prebiotics and synbiotics which are designed to beneficially alter the bacteria present in our gut. Most people will have a predominance of Bacteriodes bacteria in their digestive systems, these have both pathological and neutral effects. For optimal health it would be better for us to have a gut dominated by Bifidobacteria and Lactobacilli. The health promoting effects of these bacteria include prevention of the growth of harmful bacteria, improvement of immune functions, reducing gas/bloating problems, improved digestion and better absorption of essential nutrients and vitamin synthesis. A probiotic, prebiotic or symbiotic supplement may be a way of beneficially altering the bacterial status of our colon.
A probiotic is a supplement containing live friendly bacteria which aim to improve intestinal bacteria balance. Probiotics are available as yoghurts, fermented milks, fortified fruit juices and freeze dried capsules/powders.
A prebiotic is a food that stimulates the growth of the beneficial bacteria already present in the colon. Fructooligosaccharides (FOS) which can be bought as powders are the most common prebiotics available. Natural prebiotics can be found in asparagus, onion, chicory and garlic.
Synbiotics are a mixture of probiotics and prebiotics.
Tomorrow I will look further into these supplements and their use in the alleviation of IBS specific symptoms.
(1)Wald A & Rakel D. 2008. Behavioural and complementary approaches for the treatment of irritable bowel syndrome. Nutrition in Clinical Practice. 23:284-292
(2)Heitkemper MM & Jarrett ME. 2008. Update on irritable bowel syndrome and gender differences. Nutrition in Clinical Practice. 23:275-283
Written by Ani Kowal