CONDITIONS & DISORDERS
IRRITABLE BOWEL SYNDROME This article will be outlining current and potential treatment approaches of IBS, including genetic links in its aetiology. Irritable bowel syndrome (IBS) is the most common functional gastro-intestinal disorder, characterised by abdominal pain and changes to stool frequency, form or both. It is reported to effect on average 11% of the worldwide population.1 Whilst symptoms are not likely to be indicative of physical damage, they can have a significant detrimental effect on quality of life. Global prevalence rates of IBS are estimated to be around 7-21%,4 although the actual incidence may be much higher, as many people may not seek medical help for their symptoms. Twice as many women as men are thought to be affected and symptoms of IBS may cross-over into gender-specific conditions such as endometriosis in some of these women. As a functional gastrointestinal disorder, a diagnosis is made once other medical causes for symptoms have been ruled out. Rome IV criteria may be used to inform a diagnosis of IBS subtype according to stool type: • Diarrhoea predominant (IBS-D), which is the commonest subtype. • Constipation predominant (IBS-C). • Mixed, fluctuating between diarrhoea and constipation (IBS-M). • Unclassified (IBS-U)2. These subtypes are no longer distinct, but are recognised as being on a spectrum, depending on ‘the person’s quantity, intensity and severity of different symptoms’.2 As the diagnosis of IBS is based on exclusion of other medical causes, clinical investigations carried out by a patient’s GP may include: • full blood count (FBC) to assess for anaemia; a raised platelet count may suggest active inflammation as an alternative cause for symptoms; • inflammatory markers, such as
erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), may be raised if there is active inflammation or infection; • coeliac serology to exclude coeliac disease, particularly if there is diarrhoea-predominant IBS or mixed symptoms.3 WHAT CAUSES IT?
The exact cause of IBS remains unclear, as symptoms and pathology differ case to case. Suggested causes of symptoms are: • increased gut sensitivity; • increased or reduced gut motility; • psychological factors, ie, stress and anxiety; • post-infective (following a gastrointestinal infection). As genetic research techniques advance, there has been an interest in identifying factors that may be linked to IBS development. A recent large scale study looked at genetic data from over 346,000 participants in the UK Biobank and from further centres in Europe and the US. A significant association was found between chromosome 9q31.2 and 13 other loci. Variants at locus 9q31.2 were associated with the risk of IBS in women, but not shown in men.5 Whilst the study was well-powered, there was no way to confirm clinical diagnosis of IBS in participants, as donors in the Biobank self-report this data. The identification of this significant risk locus for IBS may help to highlight a link between sex hormones and autonomic nervous dysfunction in people with IBS – interesting insight of the higher incidence of IBS in women – and potentially leading to novel treatments following further research. Early childhood development may also be of importance, with a recent
Jessica English RD Freelance Dietitian, founder at Level Up Nutrition Jess runs Level Up Nutrition, working with individuals on a one-to-one basis in Brighton and online UK-wide. Jess has a special interest in health communications and global public health nutrition.
REFERENCES Please visit the Subscriber zone at NHDmag.com
www.NHDmag.com June/July 2019 - Issue 145
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