Nutrient intake, diet quality, and diet diversity in irritable bowel syndrome and the impact of the low FODMAP diet
Research question: What is the habitual nutrient intake, diet quality, and diet diversity in individuals with IBS without constipation and does the low FODMAP diet impact on these parameters compared with control diets?
Key findings: In this secondary analysis of two randomized controlled trials in IBS, many individuals failed to meet national recommendations for a number of nutrients, including fat, fibre, iodine, and selenium. A low FODMAP diet, when delivered by a specialist dietitian, did not significantly impact the intake of most nutrients or diet diversity, however, it led to lower diet quality compared with controls.
Staudacher HM, Ralph FSE, Irving PM, Whelan K, Lomer MCE. Nutrient Intake, Diet Quality, and Diet Diversity in Irritable Bowel Syndrome and the Impact of the Low FODMAP Diet. 2019
The full paper can be accessed at:
https://www.ncbi.nlm.nih.gov/pubmed/31029650
Prebiotics in IBS
In patients with irritable bowel syndrome there are conflicting messages about dietary fibre for improving symptoms. On one hand the low FODMAP diet restricts the type of dietary fibres that may be fermented by gut microbes, however specific types of fibre that are fermented by a select few types of gut microbes, called prebiotics, have been shown in some studies to improve symptoms and increase some types of probiotic bacteria (bifidobacteria) in IBS.
We recently performed a systematic review and meta-analysis that showed that while in general prebiotics did not improve symptoms in IBS they did increase bifidobacteria, sub-analysis revealed that some types of prebiotics may actually improve symptoms in IBS whereas others may make symptoms worse, we also found that prebiotic doses lower than 6 g/d could improve symptoms.
We concluded that if a prebiotic isn’t a type of FODMAP fibre (fructan, FOS, OF, inulin) then it may improve IBS symptoms when taken at a dose of less than 6 g/d.
Wilson B, Rossi M, Dimidi E, Whelan K. Prebiotics in irritable bowel syndrome and other functional bowel disorders in adults: a systematic review and meta-analysis of randomized controlled trials. 2019
The full paper can be accessed at:
https://academic.oup.com/ajcn/article/109/4/1098/5428039
Diet low in FODMAPs reduces symptoms in patients with irritable bowel syndrome and probiotic restores bifidobacterium species: a randomized controlled trial.
We have recently published a large ground breaking trial undertaken in 104 patients with irritable bowel syndrome. We wanted to determine if the low FODMAP diet is better than a placebo diet. We wanted to use this trial design as it provides the highest quality evidence for the effectiveness of treatments in medical research.
Patients were allocated to either receive low FODMAP dietary advice or sham (fake) dietary advice from a dietitian.
Other studies have shown that a low FODMAP diet can lead to changes in the gut microbiome (bacterial community in the gut), so at the same time we also allocated patients to receive a probiotic or a placebo supplement to see if the probiotic could prevent these changes in gut microbiome.
We found that after 4 weeks, the low FODMAP diet improved gut symptoms and aspects of quality of life in around 60%-70% of patients. When analysed individually, the probiotic was not as effective as the low FODMAP diet in improving IBS symptoms, but we need bigger studies to confirm this. Interestingly, the probiotic did help to preserve one type of beneficial bacteria, Bifidobacteria.
What does all this mean? This is strong evidence that a low FODMAP diet will help improve symptoms in most people with IBS. We don’t have enough information at this stage to routinely ask patients to add in a probiotic when they follow a low FODMAP diet.
The next step is to find out whether reintroducing FODMAPs back into the diet (which is a key stage in the low FODMAP diet process) is able to increase the Bifidobacteria back to the usual level.
Staudacher HM, Lomer MCE, Farquharson FM, Louis P, Fava F, Franciosi E, Scholz M, Tuohy KM, Lindsay JO, Irving PM, Whelan K. Diet low in FODMAPs reduces symptoms in patients with irritable bowel syndrome and probiotic restores bifidobacterium species: a randomized controlled trial. Gastroenterology. 2017
The full paper can be accessed at:
http://www.sciencedirect.com/science/article/pii/S001650851735744X
FODMAP composition data now available for foods eaten by ethnic minority groups
The King’s College London FODMAP group recently identified and measured the FODMAP content of foods commonly consumed by ethnic minority groups.1 Over 350 dietitians were invited to complete a survey to identify foods commonly consumed by ethnic minority groups based on how important they believed measuring their FODMAP content would be. Consultation with focus groups, including members of ethnic minority groups and experts in the low FODMAP diet, were also undertaken to ensure appropriate foods were selected for analysis. The top 20 ranked foods underwent FODMAP analysis using validated analytical techniques in conjunction with our collaborators at Monash University. Of the 20 foods analysed, five were identified as significant sources of at least one FODMAP (see table below). Although more foods still need to be analysed this study has made a positive step forward in broadening the potential reach, acceptability and equality of access to the low FODMAP diet across different groups.
Foods identified as significant sources of FODMAPS
| Food |
Fructans |
|
GOS |
|
| |
g/100g |
g/portion |
g/100g |
g/portion |
| Channa dal |
0.13 |
0.11 |
0.36 |
0.29 |
| Fenugreek seeds |
1.11 |
0.13 |
1.27 |
0.15 |
| Guava |
0.41 |
0.33 |
nd |
nd |
| Karela |
nd |
nd |
1.12 |
0.90 |
| Tamarind |
2.35 |
0.28 |
0.02 |
<0.01 |
nd, not detected
Reference:
Prichard, R, et al.: Fermentable oligosaccharide, disaccharide, monosaccharide and polyol content of foods commonly consumed by ethnic minority groups in the United Kingdom. Int J Food Sci Nutr, 67: 383-90, 2016.
Dr Miranda Lomer awarded an MBE in the Queen’s Birthday Honours 2016
Dr Miranda Lomer, Reader in Dietetics, was awarded an MBE for services to dietetics and gastroenterology.
Dr Lomer is a Senior Consultant Dietitian in Gastroenterology at Guy’s and St Thomas’ NHS Foundation Trust. She is a leader in the dietary management of functional bowel disorders and inflammatory bowel disease and has published British Dietetic Association guidelines for these conditions.
Dr Lomer leads an educational course for dietitians on the low FODMAP diet and has trained over 1,000 dietitians in this successful dietary treatment for irritable bowel syndrome.