THE LOW-FODMAP DIET: AN OVERVIEW OF ITS DEVELOPMENT AND APPLICATIONS Diets involving the restriction of fermentable carbohydrates in order to provide relief from the symptoms of bloating, pain and other gastric discomfort, have been emerging for a number of years. In particular, a diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols (low-FODMAP) diet has increased in popularity. There has been considerable interest in the low-FODMAP diet and its applications in IBS and other conditions since its conception in 2005 and it has been recommended as a second-line intervention for IBS by the BDA since 2013, for relief of symptoms of bloating, pain and diarrhoea.1,2 IBS is thought to affect between 7-10% of people worldwide3 and over 80% of those with IBS report a link with food.4 Therefore, there is a continued interest in a diet which will help in some way to alleviate these symptoms, however much they may vary between individuals. WHY WAS IT DEVELOPED?
For some time, it was recognised that though certain foods may be more ‘gas producing’ than others, ie, brassicas, dairy, beans, pulses and legumes, there had never been a recognised group classification of these foods and their components. This meant that potential dietary interventions were difficult to assess and there was no set guidance for identifying individual tolerance levels. The collective term ‘FODMAPs’ was coined in 2004 by a team of researchers at Monash University in Australia, who were keen to create a dietary intervention that included all of the problematic short-chain carbohydrates that had previously been identified. Those which were included had been recognised to cause symptoms due to malabsorption, maldigestion,
fermentation and osmotic load. Whereas previously, much research had focused on eliminating only one or two of these FODMAPs, the research team’s theory was that by removing all the FODMAPs – and carrying out a phased, carefully monitored reintroduction – dietary triggers and individual tolerance levels could be better assessed.5 The team then began to have their efforts recognised internationally through the development of further studies, initially through a hypothesis around the pathogenesis of Crohn’s disease.6 Overall, the team hypothesised that dietary restriction of these short-chain carbohydrates would reduce luminal distension (through reducing water/gas retention) and potentially bring relief to individuals with IBS who report visceral hypersensitivity. A small observational study showed improvement of symptoms following restriction of fructose.7 An exacerbation of symptoms with the reintroduction of fructose and fructan was then noted in a blinded controlled trial that re-challenged those who had previously reported improvement following restriction of fructose.8 This continued development included teaming up with international researchers in New Zealand and in the UK. Research began into the development of assessment tools, detailed food analysis, including cutoffs for high/low FODMAPs and assessment of the diet’s efficacy in other conditions.5
NUTRITION MANAGEMENT
Jessica English RD Self-employed Freelance Dietitian, founder of Level Up Nutrition Jess runs Level Up Nutrition, working with individuals on a one-to-one basis in Brighton and virtually UK-wide. She has a special interest in health communications and global public health nutrition. www.levelup nutrition.co.uk
REFERENCES Please visit the Subscriber zone at NHDmag.com
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NUTRITION MANAGEMENT WHAT IS INVOLVED IN THE DIET TODAY?
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A low-FODMAP diet involves an exclusion of high-FODMAP foods for around four to six weeks, with a gradual, phased reintroduction in order to assess individual tolerance levels, which then results in a maintenance diet. If no improvement is seen within four weeks of starting the elimination phase, it is recommended to stop the intervention and other options should be considered.2 Due to the complex, restrictive nature of the diet, it is recommended to be carried out with supervision from a healthcare professional. There is limited research into the effectiveness of the diet when not dietitian-led. The initial, low-FODMAP elimination phase is followed by a period of food re-challenging in order to assess individual tolerance levels. When the re-challenges are complete, a maintenance diet can be devised which minimises the FODMAPs that have caused discomfort, reintroducing others at a tolerated level, but providing an otherwise varied, balanced diet. It is important that nutritional adequacy of the diet is assessed throughout all stages.
POPULARITY
The diet has increased in popularity in recent years, as more and more people seek out help for intolerances and functional gut disorders. The development of an app by Monash University and others has meant that dietary choices for many who are undertaking the intervention are somewhat clearer. This may, however, potentially lead to individuals undertaking the diet without the assistance of a trained healthcare professional, risking nutritional deficiency and lack of guidance in the reintroduction phase. Many (non-medical) websites and blogs that list the details of a low-FODMAP diet fail to explain the reintroduction phase at all, instead usually listing high and low sources of FODMAPs. Anecdotally, I’ve also spoken to many people who’ve stuck to the elimination phase for months at a time, with great reluctance to, or misunderstanding of, continuing on into the reintroduction phase. There also appears to be a lack of education or support provided by GPs and nursing staff, with recommendations being given for patients to
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The low-FODMAP diet
trial the diet seemingly with just general blanket advice, limited further support and no referral to a dietitian. This can lead to confusion and anxiety for patients, as the diet is not only very restrictive, complicated and time consuming, but also requires a higher level of cooking skills and potentially increased food costs, as many processed foods are ruled out. For those not confident with all this, or who are not computer literate, the diet will likely be daunting. EFFICACY OF A LOW-FODMAP DIET IN IBS
Various studies have been developed to investigate the efficacy if a low-FODMAP diet versus other traditional and non-traditional interventions. Continued research into a low-FODMAP diet versus NICE guidelines has shown contrasting results between different studies. In UK research from 2011, those following a low-FODMAP diet reported a 76% reduction in symptoms compared with 54% of participants who were following general NICE guidelines for IBS management. In particular, there was a significant improvement in symptoms of bloating, flatulence and abdominal pain in the low-FODMAP group.9 A US study looking into the effectiveness of a low-FODMAP diet compared with a diet following modified NICE guidelines in those with diarrhoea-predominant IBS (IBS-D), showed similar overall outcomes for symptom improvement, although improvements in specific markers of pain and bloating were more marked in the low-FODMAP group.10 A recent Swedish study also showed similar outcomes
following comparison of a low-FODMAP diet and a more traditional ‘IBS diet’.11 In 2016, a small study sought to compare the effects of a 12-week programme of Hatha yoga with a 12-week FODMAP intervention.12 This study showed no significant difference in overall symptom improvement between the two interventions at 12 and 24 weeks. However, there was a slightly higher attrition rate for the FODMAP group. Despite the relatively small sample size (n=59) of this study, it highlights the potential for more intricate gut-brain interactions in IBS and the need for continued research in this area. A recent small study (n=44) looking into the effect of a prebiotic supplement when compared with a low-FODMAP diet in a group of participants with either IBS or functional abdominal distension, has shown a prebiotic supplement to be an effective treatment.13 Both treatment groups reported statistically significant improvements to IBS symptoms, although the prebiotic group didn’t report significant improvements in borborygmi or flatulence. There was no difference in treatment effect between groups; however, post-treatment symptoms returned in a different manner for each group; with improvements generally continuing for two weeks post-treatment for the prebiotics group. Nevertheless, symptoms reappeared immediately for many in the lowFODMAP group. As many high-FODMAP foods are also prebiotics, it might seem an unlikely treatment, as prebiotics generally provide substrate www.NHDmag.com April 2019 - Issue 143
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Changes to variation and proliferation of gut microbiota . . . which were assessed during this study, have led to the development of further research into prebiotics and a low-FODMAP diet.
for microbiota and increase gas production; worsening symptoms. However, longer-term administration of these prebiotics (as with food intake) seems to show an adjustment in the microbiota, eventually returning to pretreatment levels. Changes to variation and proliferation of gut microbiota (an increase in Bifidobacterium sequences in the prebiotic group and a decrease in the lowFODMAP group, alongside a decrease of Bilophila wadsworthia in the prebiotic group and an increase in the low-FODMAP group), which were assessed during this study, have led to the development of further research into prebiotics and a lowFODMAP diet. This includes a study looking into the use of a prebiotic supplement alongside a lowFODMAP diet in the treatment of IBS.14 The results showed adequate symptom relief and presented a potential method for identifying responders and non-responders to low-FODMAP treatment through stool and urine metabolite analysis, which could provide insight into mechanisms and help to individualise treatments for IBS in the future. This may also help to address any issues arising from altered gut microbiota following the elimination of a standard low-FODMAP diet. In general, there appears to be good evidence to support improvements in symptoms of pain, bloating and diarrhoea in those with IBS who fit the criteria for undertaking the diet, although it may be slightly less effective in treating symptoms associated with constipationpredominant IBS (IBS-C). 34
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OTHER APPLICATIONS OF A LOW-FODMAP DIET
Research is being conducted into the efficacy of the diet in treatment of a variety of health conditions. These include endometriosis and small intestinal bacterial overgrowth (SIBO), infant colic health and paediatric IBS. In endometriosis, dietary interventions have generally had limited success. As there is a considerable overlap with symptoms of IBS and endometriosis (including increased reported visceral hypersensitivity), researchers at Monash University have begun to investigate potential benefits of a low-FODMAP diet.13 Initial results suggest that there may be some improvement in symptoms for those with endometriosis who report gut symptoms, though further research is needed. As regards SIBO, there is a lack of consensus worldwide regarding its diagnosis and management. Again, there are many overlapping symptoms with IBS. Many variations of elemental and elimination diets are recommended from various sources and a lowFODMAP diet may potentially reduce unwanted symptoms of bloating and pain. However, due to the inherent difficulties in diagnosing and assessing efficacy of any treatments, conclusive research into this area is limited at this time. PRACTICAL CONSIDERATIONS
Those undertaking a low-FODMAP diet are recommended to do so under the supervision of a qualified healthcare professional; ideally
NUTRITION MANAGEMENT a trained registered dietitian who has the expertise needed to assess nutritional adequacy. Participants need to be assessed for their understanding of the nutritional limitations of the diet, ability to plan and prepare meals and be aware of the potentially increased financial and time burden. Education sessions will need to effectively explain the importance of the reintroduction phase and the need for assessing individual tolerance levels. Due to the restrictive nature of all elimination diets, attention also needs to be paid to the potential for links to disordered eating in those who are undertaking a low-FODMAP diet. Investigations into short-term changes to microbiota following the elimination phase of the diet suggest a negative effect, potentially reducing overall calcium intake14 and decreasing concentrations of potentially beneficial butyrateproducing bacteria.15 Research into any long-term alterations to the microbiota following the reintroduction phase of the diet is lacking and so it is unclear what effect this may have on microbiota and, potentially, on overall health. More research is needed in this area to establish any long-term effects on microbiota and gut health in general. Dietary fibre appears to be particularly important in gut health, for increasing variability of microbiota, but also for gut motility, stool bulk and consistency, which may affect IBS symptoms. It may prove difficult to achieve the recommended 30g/day of fibre,16 particularly during the elimination phase; therefore, particular attention may need to be paid to this over the longer term during the maintenance phase. It is also apparent that the implementation of this diet, education sessions and continued support is time and resource heavy. This may mean that it is unsuitable for settings within the NHS, with time-limited consultations and where dedicated provisions cannot be made. Group sessions may provide a more suitable setting for reaching more patients who would potentially benefit, although these aren’t suited to everyone. CONCLUSION
The low-FODMAP diet has been shown to be effective in alleviating symptoms of pain, bloating and increased stool satisfaction in those
with IBS in a number of well-controlled, shortterm studies. Nevertheless, due to the restrictive nature of the diet, it is not suitable for everybody. There is also only very limited evidence from observational studies which address the effectiveness of maintaining the diet over the longer term and there have been concerns raised over potential deleterious effects on microbiota, taking into consideration limited overall fruit, vegetable and fibre intake and the potential prebiotic effect of these foods. Individuals should be thoroughly assessed prior to commencing the diet, which should ideally be carried out by a qualified healthcare professional. This should ensure that the intervention is suitable and limits potential for abuse or misinterpretation of the diet. As per NICE guidance and BDA guidelines, there are first line treatments and assessments which may negate the need for an elimination diet in those with IBS. Potential benefits need to be weighed up against the practical considerations of implementing the diet and, as always, informed patient/client choice is paramount.
Prebiotic Supplements Used in studies alongside a low FODMAP diet* BimunoÂŽ naturally increases good bacteria in your gut in just 7 days**
Available at naturaldispensary.co.uk, bimuno.com, Holland & Barrett, Boots and Amazon For more information please contact hcp@bimuno.com *Study found that Bimuno reduced symptoms of IBS, comparable to a low-FODMAP diet www.gastrojournal.org/article/S0016-5085(18)34687-0/pdf **Scientific data shows that daily use of Bimuno increases gut bifidobacteria levels within 7 days, results may vary
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