Diet Tips:Research article: Not all FODMAPs are equal

By Caroline Tuck (APD, PhD Candidate)

An interesting study was published in 2013 about the effects of different FODMAPs.

FODMAP is an acronym for a group of carbohydrates that have been shown to cause symptoms in people with irritable bowel syndrome (IBS). The acronym stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols and includes the following carbohydrates:

·         fructose

·         lactose

·         sugar polyols (including sorbitol and mannitol)

·         fructans

·         galactooligosaccharides

Although these 5 sugar subgroups have been grouped together, they appear to have a different effects on the gut. This study compared the effects of fructose and fructans.

Sixteen healthy volunteers participated in the study. Subjects were given 4 different solutions: glucose (a well-digested/absorbed sugar) which acted as a control (or placebo); fructan; fructose or fructose with added glucose. After consuming each solution, subjects underwent MRI scans to assess the water content of the small intestine and the gas content of the large intestine.

The study showed that fructose caused an increase in the water content of the small intestine (probably due to osmosis), while fructans increased the gas content of the large intestine. The study highlights that different FODMAPs behave differently, even within the same gut. It also helps us to understand why different FODMAP may contribute to different IBS symptoms. The study suggests that dietitians should tailor a person’s low FODMAP diet to mitigate specific IBS symptoms.  

If you would like to read the full research article, the reference is here: Murray, K., V. Wilkinson-Smith, C. Hoad, C. Costigan, E. Cox, C. Lam, L. Marciani, P. Gowland and R. C. Spiller (2014). "Differential effects of FODMAPs (fermentable oligo-, di-, mono-saccharides and polyols) on small and large intestinal contents in healthy subjects shown by MRI." Am J Gastroenterol 109(1): 110-119.

           

Diet Tips:Talking tofu

By Dr Jane Varney

There’s been a lot of discussion regarding the FODMAP content of tofu recently, so we're going to clear up some of the confusion!

Also known as bean curd, tofu is a nutritious and versatile food that features heavily in vegetarian and Asian cuisines. Made by coagulating soy milk and pressing the curds into block moulds, it is low in fat, low in kilojoules and high in protein, making it a healthy addition to any diet. 

There are a wide range of tofu varieties on the market that vary in moisture content and texture. Typically, firmer varieties have had more water pressed out of them, while softer varieties are either unpressed or have had less water pressed out of them.

 

Silken tofu is unpressed and has the highest water content, making it a suitable addition to creamy foods such as smoothies, desserts, sauces, and dips. It is often used as a substitute for eggs in baked dishes. Firmer varieties of tofu have a lower water content and can be sliced, baked, fried, stir-fried or scrambled.

But what is the FODMAP content of tofu and how much can safely be included in a low FODMAP diet?

The answer to this question depends on the variety of tofu in question. Our analyses have revealed that silken tofu is high FODMAP in a 140g serve, due to the presence of oligos (GOS and fructans), whereas firm tofu is low in FODMAPs in a 170g serve.

Tofu, firm, drained	Serving size	Rating
1 serve	170g (⅔ cup, cubed)	Low
½ serve	85g (⅓ cup, cubed)	Low
Tofu, silken, drained
1 serve	140g (⅔ cup)	High
½ serve	70g (⅓ cup)	High

 Why the difference, we hear you ask? We think it is due to differences in food processing methods. As you might remember from previous blog posts, FODMAPs (particularly fructans and GOS) are water soluble, so drained, firm tofu (with a lower water content) is lower in FODMAPs than silken tofu that has a high water content.

The take home message: drained, firm tofu is a nutritious, low FODMAP source of protein that can be enjoyed in Asian and vegetarian dishes. 

Check out our tofu recipes included in the app and previous blog posts:

Marinated tofu recipe

Scrambled tofu recipe

Vegan, gluten free french toast

Diet Tips:Prebiotics and probiotics: what are they and should I be including them on a low FODMAP diet?

By Dr Jane Varney

Let’s start with prebiotics. A prebiotic is a type of fibre that passes through the gastrointestinal tract undigested and stimulates the growth and/or activity of certain ‘good’ bacteria in the large intestine. While all prebiotics are considered ‘fibre’, not all fibre has prebiotic effects. Because certain FODMAPs have prebiotic effects, namely fructans and galacto-oligosachairdes (GOS), a low FODMAP diet restricts intake of prebiotic fibres. 

This is one of the reasons why a low FODMAP diet is not considered a lifetime diet and why the rechallenge phase is so important. Indeed, a prebiotic rich diet is considered a healthy diet for the general population (without IBS). Diets rich in prebiotic fibres may encourage a healthy balance of gut bacteria, potentially benefiting digestion, the absorption of minerals and immune system function.

Probiotics on the other hand, are live microbial food supplements that feed on prebiotics. Common varieties include lactobacilli or bifidobacteria. Probiotics are available in a number of forms: they are found naturally in some yoghurts and fermented milk, they are sometimes added to infant formula and they are available as dietary supplements. 

Probiotics may play a role in gut health, by inhibiting the growth of pathogenic (disease causing) bacteria, assisting in the digestion and absorption of nutrients, contributing to short chain fatty acid production and maintaining a healthy immune system.

There is some evidence that probiotics can help with IBS symptoms, but this may vary depending on which probiotic preparation is used. Our advice is to try one management strategy at a time. Commence a low FODMAP diet first and if you have not achieved good symptom control after 2-6 weeks on the diet, then discuss other management strategies with your dietitian, including the possibility of introducing probiotics.

 

Diet Tips:What are the Oligos?

Dr Jaci Barrett (Accredited Practising Dietitian)

You may have noticed the ‘oligo’ category of FODMAPs within the Monash University low FODMAP diet app. It combines two common oligosaccharides that are poorly absorbed and can trigger IBS symptoms, the fructans and galacto-oligosaccharides (GOS).

We have had several requests from the public asking us to separate these FODMAPs, so we wanted to take the opportunity to explain why they are grouped together.

Fructans are chains of fructose sugars joined together with glucose at the end.

In order to absorb fructans, we need to break the sugars down into single sugars (monosaccharides). But, we can’t. Humans do not produce any enzymes that can break down the bonds between these sugars, so the fructans move through the gut completely unabsorbed. 

When the fructans meet bacteria in the large intestine, they are fermented which produces gases. In healthy people this causes a bit of wind and is part of normal, healthy digestion. In IBS, where the gut is hypersensitive and motility disturbances are common, this results in bloating, abdominal discomfort and altered motility.

The same occurs with GOS. GOS are chains of galactose sugars joined together with glucose at the end.

Again there is no human enzyme capable of breaking down the bonds between the galactose sugars, so they move through the gut unabsorbed. Poor absorption of GOS leads to symptoms in IBS patients.

So these oligosaccharides (oligos) always pass through the gut and escape digestion. They have beneficial effects whereby they encourage the growth of good bacteria and act as prebiotics, but if you have IBS you might notice symptoms after ingesting foods rich in the oligos.

We list them together on the app because they have the same activity in the gut, but it is common that not all oligo-containing foods are triggers for everyone. This is not due to the type of oligos – fructans vs GOS – rather it is due to your individual response to different high FODMAP foods. You may find you can eat garlic but not onion, for example, both of which are high in fructans. Other people find they can eat chickpeas, but not red kidney beans, both high in GOS. 

The final long term low FODMAP diet is a modified version of the diet, individualised for you based on your reactions to food reintroductions. Keep trying new foods. Within each FODMAP subgroup you may tolerate some foods, but not others.

Diet Tips:Rice Milks Revisited: Moving from red to green rating in app

By Dr Jane Muir 

Everyone was very disappointed when our rating for rice milk was red = high FODMAP!

We have had many requests to conduct further testing of rice milks from different countries.  Our team has just completed testing rice milks from Australia, United Kingdom and the United States.

Remember that the analysis of all FODMAPs in food is a complex and time-consuming process undertaken by the laboratory team here at Monash.  Some foods (particularly processed foods) present technical challenges.  Rice milk is one of these challenging foods. 

Currently, rice milk has been given a red rating in the app.  This was due to the presence of very high level of oligosaccharides (Oligos) that our team detected in the rice milk samples. As we discussed in our last rice milk blog – this high level of Oligos are due to the enzymatic breakdown of the rice flour starch to release glucose (this is how rice milk is made).  As you can see from the diagram below, rice starch is a large and complex carbohydrate - made up of chains of glucose (these can be very long - thousands of glucose units long). The enzymes used to make rice milk sometimes fail to completely break down the rice starch and as a result some small oligos are left behind.  The key point here is that these types of starch-derived oligos are digestible, unlike the Oligos- fructans and GOS. So these are not really FODMAPs!

Our laboratory team has discovered that these starch-derived oligos get mixed up with the FODMAP - GOS-oligos during the laboratory analysis. This means it has been difficult to know how much of these oligos are starch-derived and therefore well tolerated, and how much is GOS, a FODMAP, poorly tolerated. The team has recently established a new technique to answer this question. As a result of their hard work, they have discovered that there is little GOS in rice milk and indeed these Oligos are probably starch-derived and therefore well tolerated. All rice milks have been re-tested using this new method.

We have now reviewed the rating for rice milk and will be modifying this accordingly.  We have given a safe (low level greenrating) for 200 ml of rice milk per sitting.  The results for the Australian, UK and US will be in the app very soon. We apologize for any confusion this may have caused - but this is science in action! and part of the ongoing research and refinement of the Monash University Low FODMAP diet.

Be careful:  There are still some fructans present in some rice milks and therefore we do not recommend very high quantities of rice milk in one sitting.

So will this problem of starch-derived Oligos affect other food ratings in the app?  We have reviewed other foods in the app and we have not found any other foods which have been affected by this technical issue.

 

 

Diet Tips:Dietary Fibre Series - Prebiotic Fibre

Erin Dwyer (Research Dietitian)

 

We know eating enough fibre on a low FODMAP diet can be challenging and that getting the right mix of fibres is very important, so let’s discuss prebiotic fibre.

There has been a lot of talk recently about prebiotics and probiotics and how they can affect the gut, but what really are they?

Prebiotics (including resistant starch) are non-digestible fibres found in certain foods that can stimulate the growth of some bacteria. This means that instead of being broken down within the gut the prebiotic fibre travels through the gut, stimulating growth and/or activity of probiotics i.e. the good bacteria!

Here's a list of foods that are high in prebiotics that have a 'green serve’ size – take a look at the Monash low FODMAP App to find out more!

Fruits and Vegetables	Grains and Cereals	Legumes, lentils, nuts and seeds
Artichokes	Oats	Mung beans
Beetroot	Buckwheat kernels	Lima beans
Butternut Pumpkin	Wheat free Gnocchi	Nuts – Almonds and hazelnuts
Pomegranate seeds	Wheat bran	Canned chickpeas
Dried paw paw	Pasta (wheat/spelt), cooked and cooled	Canned lentils

If you are following or have followed a low FODMAP diet you may notice many of the foods listed above are high in FODMAPs. This is because fructans and galacto-oligosaccharides (GOS) are prebiotic fibres.

So if prebiotics are often high in FODMAPS, but considered part of a healthy diet, how can they be included on a low FODMAP diet?

Here are a few ideas to get you started

·         Firstly, remember that a low FODMAP diet is only meant to be LOW in FODMAPs, not completely depleted of FODMAPs

·         Also, after the initial strict phase of the diet, you may find through the rechallenge phase that you actually tolerate moderate serves of fructan and GOS rich foods quite well

·         Certain canned legumes that have been rinsed and drained are lower in FODMAPs - you can find a safe ‘green serve’ of legumes and lentils in the Monash FODMAP App. Try this recipe http://fodmapmonash.blogspot.com.au/2016/01/low-fodmap-vegan-coconut-pumpkin-curry.html

·         You can purchase wheat free Gnocchi for a low FODMAP option, serve it with a low FODMAP pasta sauce and salad – You can try this recipe http://fodmapmonash.blogspot.com.au/2016/09/low-fodmap-chicken-and-gnocchi-pasta.html

·         Add ¼ cup (green serve) of pomegranate seeds to your salad for great texture and a little sweetness

·         Snack on some almonds or hazelnuts (10 for a green serve)

It is also important to remember to continually test your tolerance to FODMAP containing foods, you may find you can tolerate different prebiotics in varying amounts. For some guidance in reintroduction you can look back on this past blog post:

http://fodmapmonash.blogspot.com.au/2015/06/just-2-6-weeks-it-is-not-diet-for-life_8.html

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.