Dietary Fiber and FODMAP-Restricted Diet in IBS
Background Dietary fibre supplements have been advocated for the management of chronic constipation (CC) and irritable bowel syndrome (IBS). Recently, a fermentable oligosaccharide, disaccharide, monosaccharide and polyol (FODMAP) restricted diet has been recommended for IBS.
Aim To systematically examine recent evidence for dietary interventions with fibre in CC and IBS and FODMAP-restricted diet in IBS, and provide recommendations.
Methods We searched PUBMED, MEDLINE, OVID and COCHRANE databases from 2004 to 2014. Published studies in adults with CC and IBS and constipation-predominant IBS (IBS-C) that compared fibre with placebo/alternative and FODMAP-restricted diet with alternative were included.
Results Of 550 potentially eligible clinical trials on fibre, 11 studies were found and of 23 potentially eligible studies on FODMAPs, six were found. A meta-analysis was not performed due to heterogeneity and methodological quality. Fibre was beneficial in 5/7 studies in CC and 3/3 studies in IBS-C. FODMAP-restricted diet improved overall IBS symptoms in 4/4 and IBS-C symptoms in 1/3 studies and three studies did not meet inclusion criteria. There were significant disparities in subject selection, interventions and outcome assessments in both fibre and FODMAPs studies.
Conclusions Fibre supplementation is beneficial in mild to moderate CC and IBS-C, although larger, more rigorous and long-term RCTs are needed (Fair evidence–Level II, Grade B). Although the FODMAP-restricted diet may be effective in short-term management of selected patients with IBS (Fair evidence–Level II, Grade C) and IBS-C (Poor evidence–Level III, Grade C), more rigorous trials are needed to establish long-term efficacy and safety, particularly on colonic health and microbiome.
Chronic Constipation (CC) is defined by multiple bowel symptoms that include difficult or infrequent passage of stool, hardness of stool or a feeling of incomplete evaluation. It is a common problem that affects approximately 20% of the world's population, with a higher prevalence in women and the elderly. Regional estimates include from 4.1% to 22.4% in Europe, from 12% to 27.2% in North America, from 14.2% to 25.6% in Central and South America and from 2.6% to 24.8% in Asia. Irritable bowel syndrome (IBS) is defined by abdominal pain or discomfort that is associated with altered bowel habit over a period of at least 3 months. Epidemiologic trends globally give an IBS prevalence of 6.5% to 34.2%. In North America, the prevalence is 10–15% with the constipation predominant IBS subgroup (IBS-C) accounting for approximately 5%.
Although perceived to be a benign condition, CC can result in chronic illness with potentially serious complications (faecal impaction, incontinence, bowel perforation, bleeding, haemorrhoids and anal fissure), and is associated with impaired quality of life and significant healthcare burden. The course of illness in IBS is characterised by recurring symptoms, impaired quality of life, increased health care costs and reduced work productivity. The impact of these entities on patients' lives, and their burden on the healthcare system is enormous. In Johanson et al.'s analysis of health statistics from the USA, England and Wales, the occurrence of constipation increased with advancing age, with an exponential increase in prevalence after the age of 65.
A recent Dutch study by Dik et al., showed the mean total CC-related direct medical costs per patient in the first year after diagnosis were ¢310 ± 845, ¢367 ± 882 in persistent disease, ¢292 ± 808 in episodic disease and ¢263 ± 613 in nonrecurrent disease. The estimated US annual direct medical costs related to constipation alone are estimated to include approximately $1.6 billion in out-patient costs and $852 million in in-patient costs, and comprises at least 2.5 million ambulatory care physician visits every year. A recent study on the economic impact of IBS found annual international estimates of direct medical costs per patient of US $742–$7547, UK £90–£316, France ¢567–¢862, Canada $259, Germany ¢791, Norway ¢262 and Iran $92, with the cost of absenteeism and presenteeism between £400 and £900 per patient annually.
Traditionally, individuals with CC and IBS-C are advised to increase dietary fibre intake to alleviate symptoms, but data from randomised controlled trials (RCTs) regarding the benefit of this approach is limited. Also, recent attention has focused on the restriction of a group of fermentable carbohydrates, termed FODMAPs (Fermentable oligosaccharides, disaccharides, monosaccharides and polyols), which include fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), disaccharides (e.g. lactose), monosaccharides (e.g. fructose) and polyols (e.g. sorbitol), primarily in the management of IBS-C. Its rationale is that there are several individuals who either malabsorb, or are sensitive to FODMAPs, and if these foods are ingested they may result in symptoms such as bloating, diarrhoea, gas, constipation or abdominal pain that are often interpreted as IBS. FODMAPs, when malabsorbed, are highly osmotic substances that can cause an influx of water into the colon and result in diarrhoea, or through fermentation by colonic bacteria can lead to excess gas production. In individuals with visceral hypersensitivity, intestinal distension triggered by gas or fluids may either exacerbate or induce abdominal symptoms. A reduction in consumption of FODMAPs would in theory, reduce fluid transit in the gut and improve symptoms. However, because many patients on this diet have decreased fibre intake, it may also cause constipation.
Fibre is effective in the management of CC, but bloating, distension, flatulence and cramping may limit the use of insoluble fibre, especially if increases in fibre intake are not gradual. In our previous 2005 systematic review, we found methylcellulose, bran and calcium polycarbophil had poor levels of evidence to support a recommendation for or against the use of these therapies in the management of CC, and no new studies have been published on these compounds. Psyllium was found to have a fair level of evidence, with moderate levels of evidence to support its use in the management of CC. In IBS, insoluble fibre may exacerbate symptoms and provide minimal relief, but soluble fibre, such as psyllium, can be effective. Although food intake commonly precipitates symptoms of IBS, data from RCTs are limited regarding dietary manipulation and restriction, such as the FODMAP-restricted diet. A recent systematic review by Ford et al. was published regarding the management of IBS and chronic idiopathic constipation. In this systematic review, our aim is to examine the recent (last 10 years) evidence for fibre supplementation and for a FODMAP-restricted diet in the management of CC and IBS-C, and discuss their role in current management strategies for these disorders. The time period (2004–2014) was chosen because previous reviews in CC have addressed the role of fibre and newer diagnostic criteria have been established for CC and IBS-C that have been widely adopted in clinical trials, including the use of more rigorous outcome measures such as complete spontaneous bowel movements (CSBMs). Finally, the FODMAP-restricted diet has only been introduced during this time period.
Abstract and Introduction
Abstract
Background Dietary fibre supplements have been advocated for the management of chronic constipation (CC) and irritable bowel syndrome (IBS). Recently, a fermentable oligosaccharide, disaccharide, monosaccharide and polyol (FODMAP) restricted diet has been recommended for IBS.
Aim To systematically examine recent evidence for dietary interventions with fibre in CC and IBS and FODMAP-restricted diet in IBS, and provide recommendations.
Methods We searched PUBMED, MEDLINE, OVID and COCHRANE databases from 2004 to 2014. Published studies in adults with CC and IBS and constipation-predominant IBS (IBS-C) that compared fibre with placebo/alternative and FODMAP-restricted diet with alternative were included.
Results Of 550 potentially eligible clinical trials on fibre, 11 studies were found and of 23 potentially eligible studies on FODMAPs, six were found. A meta-analysis was not performed due to heterogeneity and methodological quality. Fibre was beneficial in 5/7 studies in CC and 3/3 studies in IBS-C. FODMAP-restricted diet improved overall IBS symptoms in 4/4 and IBS-C symptoms in 1/3 studies and three studies did not meet inclusion criteria. There were significant disparities in subject selection, interventions and outcome assessments in both fibre and FODMAPs studies.
Conclusions Fibre supplementation is beneficial in mild to moderate CC and IBS-C, although larger, more rigorous and long-term RCTs are needed (Fair evidence–Level II, Grade B). Although the FODMAP-restricted diet may be effective in short-term management of selected patients with IBS (Fair evidence–Level II, Grade C) and IBS-C (Poor evidence–Level III, Grade C), more rigorous trials are needed to establish long-term efficacy and safety, particularly on colonic health and microbiome.
Introduction
Chronic Constipation (CC) is defined by multiple bowel symptoms that include difficult or infrequent passage of stool, hardness of stool or a feeling of incomplete evaluation. It is a common problem that affects approximately 20% of the world's population, with a higher prevalence in women and the elderly. Regional estimates include from 4.1% to 22.4% in Europe, from 12% to 27.2% in North America, from 14.2% to 25.6% in Central and South America and from 2.6% to 24.8% in Asia. Irritable bowel syndrome (IBS) is defined by abdominal pain or discomfort that is associated with altered bowel habit over a period of at least 3 months. Epidemiologic trends globally give an IBS prevalence of 6.5% to 34.2%. In North America, the prevalence is 10–15% with the constipation predominant IBS subgroup (IBS-C) accounting for approximately 5%.
Although perceived to be a benign condition, CC can result in chronic illness with potentially serious complications (faecal impaction, incontinence, bowel perforation, bleeding, haemorrhoids and anal fissure), and is associated with impaired quality of life and significant healthcare burden. The course of illness in IBS is characterised by recurring symptoms, impaired quality of life, increased health care costs and reduced work productivity. The impact of these entities on patients' lives, and their burden on the healthcare system is enormous. In Johanson et al.'s analysis of health statistics from the USA, England and Wales, the occurrence of constipation increased with advancing age, with an exponential increase in prevalence after the age of 65.
A recent Dutch study by Dik et al., showed the mean total CC-related direct medical costs per patient in the first year after diagnosis were ¢310 ± 845, ¢367 ± 882 in persistent disease, ¢292 ± 808 in episodic disease and ¢263 ± 613 in nonrecurrent disease. The estimated US annual direct medical costs related to constipation alone are estimated to include approximately $1.6 billion in out-patient costs and $852 million in in-patient costs, and comprises at least 2.5 million ambulatory care physician visits every year. A recent study on the economic impact of IBS found annual international estimates of direct medical costs per patient of US $742–$7547, UK £90–£316, France ¢567–¢862, Canada $259, Germany ¢791, Norway ¢262 and Iran $92, with the cost of absenteeism and presenteeism between £400 and £900 per patient annually.
Traditionally, individuals with CC and IBS-C are advised to increase dietary fibre intake to alleviate symptoms, but data from randomised controlled trials (RCTs) regarding the benefit of this approach is limited. Also, recent attention has focused on the restriction of a group of fermentable carbohydrates, termed FODMAPs (Fermentable oligosaccharides, disaccharides, monosaccharides and polyols), which include fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), disaccharides (e.g. lactose), monosaccharides (e.g. fructose) and polyols (e.g. sorbitol), primarily in the management of IBS-C. Its rationale is that there are several individuals who either malabsorb, or are sensitive to FODMAPs, and if these foods are ingested they may result in symptoms such as bloating, diarrhoea, gas, constipation or abdominal pain that are often interpreted as IBS. FODMAPs, when malabsorbed, are highly osmotic substances that can cause an influx of water into the colon and result in diarrhoea, or through fermentation by colonic bacteria can lead to excess gas production. In individuals with visceral hypersensitivity, intestinal distension triggered by gas or fluids may either exacerbate or induce abdominal symptoms. A reduction in consumption of FODMAPs would in theory, reduce fluid transit in the gut and improve symptoms. However, because many patients on this diet have decreased fibre intake, it may also cause constipation.
Fibre is effective in the management of CC, but bloating, distension, flatulence and cramping may limit the use of insoluble fibre, especially if increases in fibre intake are not gradual. In our previous 2005 systematic review, we found methylcellulose, bran and calcium polycarbophil had poor levels of evidence to support a recommendation for or against the use of these therapies in the management of CC, and no new studies have been published on these compounds. Psyllium was found to have a fair level of evidence, with moderate levels of evidence to support its use in the management of CC. In IBS, insoluble fibre may exacerbate symptoms and provide minimal relief, but soluble fibre, such as psyllium, can be effective. Although food intake commonly precipitates symptoms of IBS, data from RCTs are limited regarding dietary manipulation and restriction, such as the FODMAP-restricted diet. A recent systematic review by Ford et al. was published regarding the management of IBS and chronic idiopathic constipation. In this systematic review, our aim is to examine the recent (last 10 years) evidence for fibre supplementation and for a FODMAP-restricted diet in the management of CC and IBS-C, and discuss their role in current management strategies for these disorders. The time period (2004–2014) was chosen because previous reviews in CC have addressed the role of fibre and newer diagnostic criteria have been established for CC and IBS-C that have been widely adopted in clinical trials, including the use of more rigorous outcome measures such as complete spontaneous bowel movements (CSBMs). Finally, the FODMAP-restricted diet has only been introduced during this time period.
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