Diet Tips:A dietitian’s day on a plate - Week 1 of 2

By Shirley Webber (Research dietitian)

As someone who has struggled with IBS for many years, I was relieved when I found out about the low FODMAP diet. Throughout my high schooling, I thought that having an upset stomach was “normal” and constantly feeling tired and like my head was in a giant cloud was just me being a typical teen. It wasn’t until I went to University that firstly, I realised these symptoms were not normal and secondly, I began to suspect that the symptoms may have been triggered by dietary factors.

I subsequently underwent testing to rule out serious illnesses, including coeliac disease, all of which came back negative. As a last resort, my GP suggested I have a breath tests to check my tolerance of lactose and fructose. When I found that I malabsorbed both sugars, my GP then gave me a list of all fructose and lactose containing foods that he found on the internet and told me to “never eat these foods”. That was the problem solved as far as my GP was concerned. Having seen this doctor for most of my schooling life, I trusted his every word and followed a very restricted diet for three years. I felt anxious when I ate out and found growing up in a family where food was at our core very difficult.  Increasingly, I felt that my highly restricted diet was difficult to follow and just not good enough for me.

This all changed when I read a magazine article about research into diet and gut health. This article sparked my interest in dietary research and health. At a similar time, my dad discovered that he had the same food intolerances as I did and after consultation with a dietitian, we became aware of the low FODMAP diet. Importantly, we discovered that foods should not be restricted for life, but rather reintroduced slowly to identify tolerance to specific FODMAPs. Over the next two years, I gradually tested my tolerance to new foods, reintroducing foods I was previously “not allowed”. This saw me find a much healthier diet that I could happily live with.

My personal interest in nutrition and food intolerances grew to the point that I decided to do further post graduate studies in Dietetics to better understand the complexities of food intolerances.

So now you have my personal IBS story. Next week I will give you an idea of what I eat to keep myself healthy and my symptoms at bay…a dietitian’s ‘day on a plate’.

 

Diet Tips: RESEARCH UPDATE: How important is diagnosis of Fructose malabsorption in the FODMAP approach?

By Lyndal McNamara and Dr Jaci Barrett

Background-

New research regarding breath testing and its use to diagnose fructose malabsorption in IBS has just been published. Researchers examined existing data from several prospective clinical trials involving two groups of IBS patients to see if fructose breath test results were the same when repeated over time.1  The studies also investigated reporting of gastrointestinal symptoms during fructose breath testing and the relationship between test outcome (‘positive’ or ‘negative’ for fructose malabsorption) and the experience of symptoms.1

Study 1 - 41 IBS patients - two fructose breath tests performed, with the second test completed ≥2 weeks after the first

Study 2 - 36 IBS patients - completed a single fructose breath test and kept gastrointestinal symptom diaries the day before and the day of the test

Patients in both studies followed a diet low in fibre and FODMAPs for 24 hours and were required to fast overnight prior to each breath test. Participants consumed a drink containing 35g of fructose in 200ml of water for each test and breath samples were collected every 15 or 20 minutes for up to four hours.

Results-

Study 1 – is a fructose breath test result reproducible?

Major findings

• 30% of participants, positive for fructose malabsorption in their first breath test, tested negative on the subsequent test ≥2 weeks later
• The was no relationship between the amount of breath hydrogen produced in the first and second fructose breath tests

Study limitations-

• Some study 1 participants had their second breath test performed >19 weeks after the first. This relatively long period of time between tests means that changes in diet or medications may have affected gut bacterial populations and therefore influenced the results.
• This study included a small number of participants and retrospectively analysed data from existing studies. A larger, prospective study that collects data over a longer test period would be useful to further validate these findings.
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Study 2 – are symptoms on a breath test related to breath hydrogen response?

Major findings

• Those who tested ‘positive’ for fructose malabsorption were more likely to report symptoms during a fructose breath test than those who tested ‘negative’
• This was NOT significant when test day symptom scores were adjusted to account for the participants’ usual level of symptoms (pre-test day symptom scores)

Study limitations-

• Gastrointestinal symptom data from study 2 was only collected during the breath-testing period and not the remainder of the day, so may not have captured participants who had a delayed symptom response.

Further data-

In 2013, a group of researchers in the UK conducted a study looking at the effects of fructose in the gut.2 They were examining the osmotic effect of fructose (how much water fructose moves through the gut) and did this using superior MRI technology. They demonstrated some very interesting findings:

• Fructose has an osmotic effect, delivering water through the small intestine
• Fructose has this effect regardless of whether the person has a positive or negative fructose breath test
• The authors conclude – fructose has an osmotic effect and this does not depend on breath test outcomes
• Clinical significance – a fructose breath test is not helpful in identifying fructose as a trigger.

This figure demonstrates the increase in small bowel water content (SBWC) seen on consumption of fructose in individuals with a positive fructose breath test (blue) and a negative fructose breath test (red).2 You can see there is no difference. Fructose increases SBWC regardless of breath test outcomes.

Take home messages-

• Fructose breath test results are not reproducible, i.e. you can have a positive breath test one day, and can have a negative breath test just weeks later
• There seems to be a poor correlation between fructose breath test outcome (i.e. a ‘positive’ or ‘negative’ result for malabsorption) and the experience of symptoms in individuals with IBS
• Fructose can contribute to symptoms regardless of whether a breath test is positive or negative
• The results of this and previous research DO NOT support the use of routine fructose breath tests for the diagnosis of fructose malabsorption or to guide management in people with IBS.

References:

1. Yao CK, Tuck C, Barrett J, Canale K, Philpott H, Gibson P. Reproducibility of lactulose and fructose breath hydrogen testing and impact on clinical utility. Journal of Nutrition & Intermediary Metabolism. 4:29.
2. Murray K, Wilkinson-Smith V, Hoad C, Costigan C, Cox E, Lam C, et al. Differential effects of FODMAPs (fermentable oligo-, di-, mono-saccharides and polyols) on small and large intestinal contents in healthy subjects shown by MRI. The American journal of gastroenterology. 2014;109(1):110-9.

Diet Tips:Adding glucose to high FODMAP foods – does it really help?

By Marina Iacovou (PhD Candidate and Accredited Practising Dietitian)

In an earlier blog post this year (http://bit.ly/1WvWU5Y) we speculated that although early studies suggested adding glucose to fructose may improve tolerance, the strategy was not looking promising – instead all it was doing was adding more sugar to the overall diet.  There was confusion around this strategy with individuals adding glucose to all FODMAPs, not just fructose, which is the only FODMAP that could benefit from glucose addition. Consuming glucose tablets became common practice for many people when eating onion and garlic, foods rich in fructans, not fructose, which scientifically will not improve symptoms.

We can now confidently tell you that adding glucose to foods to help with the absorption of FODMAPs, even fructose, does not work.

One of our PhD candidates, Caroline Tuck, has published work on this very topic. If you want to read the full publication, please click here.

A brief summary of the study and its findings:

• Patients with a positive fructose breath test (“fructose malabsorption”) and functional bowel disorders such as IBS, were recruited. Healthy participants were recruited as a reference/control group
• Participants were provided with 6 different sugar solutions (PART A) – some acted as control solutions (glucose only) and others were combinations of fructose and glucose, and fructans and glucose which were compared to fructose alone and fructan alone
• Additional studies (PART B) were undertaken. where glucose was added to whole foods high in excess fructose
• It was a series of two randomised controlled, double or single-blinded crossover trials – this means that the participants (and in part A the researchers) were not aware what solutions were being consumed and the solutions were given in a random order. As such the results are more reliable
• Overall, breath hydrogen scores and patient symptoms did not improve with the addition of glucose to fructose or fructan solutions, or to whole foods
• Breath hydrogen responses in healthy participants were similar to patients with functional bowel disorders – showing that “fructose malabsorption” is normal
• The results of the study, question the reliability of breath hydrogen tests in a clinical setting. 

So we can conclude that: 1) breath hydrogen tests, particularly to fructose, are unreliable – this is consistent with a previous study we posted about http://bit.ly/2fSaVcn and 2) Overall, the strategy of adding glucose to drinks or foods to lessen the effects of dietary FODMAPs on functional gastrointestinal symptoms, has no evidence.

Some of you may have been doing this already – taking glucose tablets with high fructose foods. If you really feel it helps, you can continue, but remember these points:

• Your total sugar intake will increase significantly
• Your tolerance to FODMAPs, including fructose, can fluctuate over time, so maybe this strategy is working because your tolerance to fructose has improved and you can drop the glucose without significant symptoms

Something to consider…

Tuck CJ, Ross LA, Gibson PR, Barrett JS, Muir JG. Adding glucose to food and solutions to enhance fructose absorption is not effective in preventing fructose-induced functional gastrointestinal symptoms: Randomised controlled trials in patients with fructose malabsorption. J Hum Nutr Diet. 2016.