Food & Nutrition Blog

Wholegrains & The Low FODMAP Diet.

By February 5, 2019 No Comments
Feb 05

These days, you’d be hard pressed to come across health professionals or members of the public that haven’t heard of the low FODMAP diet. Plenty of doctors and dietitians are recommending it, because of the good scientific evidence to support its efficacy in controlling symptoms of Irritable Bowel Syndrome (IBS)1.

Marnie Nitschke is an Accredited Practising Dietitian (APD) who has spent over 15 years specialising in food intolerance, gastrointestinal nutrition and IBS.  She has been working with FODMAPs since the diet was developed by a team of Monash researchers, early this century, and regularly uses it with her clients at Everyday Nutrition in Melbourne.  Marnie also teaches the Low FODMAP diet to dietitians wishing to specialise in this area.  She joins us today to share her experience and practical tips for helping clients manage dietary balance, while juggling a low FODMAP diet.

 

What are FODMAPs, and why are they a problem in IBS?

FODMAP is an acronym that stands for:

Fermentable

Oligsaccharides (eg. in wheat, rye, barley, onion, garlic, legumes)

Disaccharides (lactose – the natural sugar in dairy products)

Monosaccharides (fructose, found in fruit, some vegetables, honey)

And

Polyols (stone fruits, some vegetables and low calorie sweeteners)

In essence, these are carbohydrates found in a variety of foods, that can be difficult for us to digest and absorb.  When FODMAPs pass through our small intestine unabsorbed, they reach the large intestine, where they are rapidly fermented by the large and diverse bacterial population living inside us.  Although this fermentation is completely normal and healthy, FODMAPs can induce symptoms in people with IBS through two main mechanisms.  The first is their osmotic properties (drawing water into the bowel) and the second is their rapid fermentation (which causes gas production and pressure on overly sensitive nerve endings in the gut).

 

How do we know the FODMAP content of foods?

The Low FODMAP common diet is now well represented in the scientific literature.  These days we also have detailed information about the FODMAP content of a wide range of foods, with new results being published all the time (meaning the goal posts are constantly changing).  Anyone with a smart phone or a tablet can access this information via apps, like Monash University’s platform, which presents FODMAP data using a ‘traffic light’ system.  We’re also seeing the expansion of FODMAP certification programs, with both Monash FODMAP® and FODMAP Friendly® testing and certifying a wide range of supermarket products.

It’s great to have all of this information at our fingertips.  However, as a dietitian working in the space, Marnie sees many people who become overwhelmed by the complexity of implementing a low FODMAP diet.  It can be really difficult to understand, for those without a high level nutrition and health ‘literacy’.

 

Despite common perceptions, the low FODMAP diet is not a game of perfect

The fact is that we can’t avoid FODMAPs completely, and nor should we be trying to.  As much as they may cause unpleasant symptoms in some, FODMAPs don’t damage us in any way.  These carbohydrates actually have a number of benefits for digestive health, which is directly related to their prebiotic effect of stimulating the growth of beneficial microflora(2).

In Marnie’s practice, she sees far too many people getting overly focused on minute details about foods and serving sizes, and ultimately becoming more stressed about food, which doesn’t help their symptoms!

Many foods have a suitable ‘Low FODMAP’ dose, but may become high at increasing doses.  As an example; 1/2 slice of regular wholemeal bread is low, but servings above 1 slice become moderate to high.

 

The low FODMAP diet is not meant to be for life.

Actually, it’s an elimination diet intended to be followed for a short time (4-6 weeks), to determine whether an individual is sensitive to dietary FODMAP load.  After this initial restriction phase (where all FODMAP groups are restricted), it’s vital that people move on to the ‘challenge’ phase, where FODMAP groups are systematically reintroduced, using carefully selected foods and doses.

Emerging research is now showing the potential negative effects of restricting FODMAPs in the longer term, on gut microbiota and bowel health (3).  And in reality, most people will not react to all FODMAP groups.  For example, an individual may find the fructose in honey and certain fruits problematic, but tolerate the fructans in wheat (which is a chain length form of fructose) quite well. Working with an experienced FODMAP dietitian is the best way to ensure optimal variety and nutrition for gut health in the long term.

What about FODMAPs in grains and cereals?

Wheat products like bread and pasta can be a big trigger for people with IBS.  Traditionally, gluten has gotten the blame, but we now understand that for most people, FODMAPs are the more likely culprit (4).  The main FODMAPs found in grains and cereals are the oligosaccharide family – namely the fructans (a chain length form of fructose) and galacto-oligosaccharides (GOS).  These sugars are universally poorly absorbed, as humans do not produce the enzymes needed to break them down.  Most wheat, rye and barley products are high FODMAP for a standard serving, but there are many alternative options, including:

  • Sourdough wheat and spelt breads
  • Specially formulated and certified low FODMAP breads
  • Gluten free and rice noodles
  • All types of rice
  • Buckwheat, quinoa, sorghum, millet and teff
  • Oats (1/2 cup of rolled oats is a ‘safe’ serve)

We’re told whole grains are good for us.  So how does this work on a low FODMAP diet?

 We have robust scientific evidence to suggest that diets rich in whole grains confer protection against a range of diseases, including type 2 diabetes, obesity, cancer, and cardiovascular disease (5).  This is reflected in the Dietary Guidelines for Australia. On a strict low FODMAP diet however, the variety of these whole grains is reduced.

The positive health benefits of whole grains can come from many sources.  Fibre and antioxidants are part of the picture.  Additionally, fructans and other oligosaccharides in these grains act as prebiotics (meaning they beneficially feed ‘good’ bacteria in our gut like lactobacilli and bifidobacteria).  And finally, the by-products of bacterial fermentation in the gut include short chain fatty acids (acetate, butyrate, and proprionate) that act as fuel for cells in our bowel, keeping them healthy (6).  Processing greatly affects the nutrient composition of the end product, with whole grains being nutritionally superior to their refined versions.

As you can see, there are many reasons to keep whole grains in the diet.  Working through FODMAP challenges and experimenting with different grains is vital.  If we can establish a ‘tolerance threshold’ to each FODMAP group, that person’s long term diet will be less restricted, and contain more beneficial plant foods.  And we know this is a good thing!

 

How can someone who is sensitive to FODMAPs ensure they get enough fibre, especially prebiotic fibres like resistant starch?

This is one of the common pitfalls Marnie sees, in people adopting a low FODMAP diet.  When fruit, vegetable and grains choices are limited, it can be easy to miss out on fibre.  And it follows that constipation and altered gut flora, due to a restricted diet, are not going to help IBS or food intolerance symptoms.

While wheat bran and barley are high FODMAP, there are many suitable lower FODMAP alternatives. Rice bran, oat bran and linseeds are examples of fibres that help laxation, and contain other beneficial compounds like antioxidants, α-linolenic acid and lignans (7).  Choosing gluten free or sourdough breads with linseeds and other whole grains, is good way to increase fibre intake.

Resistant starch is another type of fibre we want to keep in the diet – as although it is fermentable and considered a potent prebiotic, it does not have the same rapid fermentation associated with FODMAPs.  Great low FODMAP sources of resistant starch include firm bananas, and cooked and cooled starches like rice and potato.  Legumes are another key food group containing resistant starch, so testing tolerance to these foods, and including ‘safe’ or low FODMAP serving sizes of legumes is essential for people who find a lower FODMAP approach helpful.

Can processing change the FODMAP content of grains and cereals?

In short – yes it can.  An example is the emergence of ‘low FODMAP’ wheat flour on supermarket shelves in Australia, as well as certified low FODMAP wheat breads, sold in commercial bakeries.  In recent advances, manufacturers have found that extra processing steps in the flour milling process (which in laymans terms equate to ‘washing’ of the flour) significantly reduces the FODMAP content.

Sourdough bread is another great example of how processing effects the FODMAPs in food.  The sourdough process involves addition of live cultures to bread dough, followed by a period of fermentation before baking.  The longer the fermentation time, the more fructans and GOS will be broken down, resulting in significantly lower FODMAP levels in sourdough wheat, spelt and some rye breads tested.  In fact, 2 slices of wheat sourdough is considered a low FODMAP serve, suitable on the initial phase of the diet.

 

How do we know each individual’s tolerance to the FODMAPs in whole grains?

 The only way to know how sensitive each individual is to the FODMAP effect of whole grains, is to systematically reintroduce them.  After the initial low FODMAP period (and if good symptom reduction has been shown), dietitians will guide clients regarding suitable foods and challenge schedules to use for this purpose.  The important point here is that various grains should be tested separately, as tolerance often varies widely between high FODMAP grains like wheat, rye and barley.

In practice, Marnie has found that while rye is high in both the fructans and GOS FODMAPs, a certain subsection of people find it better tolerated than wheat.  Ancient grains like spelt can be lower in FODMAPs and better tolerated by some individuals.  Oats are another example where testing the boundaries is important.  While the ‘safe’ serve of rolled oats is only ½ cup, many people will find they can tolerate larger amounts.

 Anecdotally, Marnie has found that people often report better tolerance to foods like pasta and bread when they’re travelling overseas.  This may be due to many factors, including the ‘holiday effect’ (equating to a more relaxed gut nervous system), as well as different grain varieties, growing conditions and processing methods used.

 

Can taking digestive enzymes help with FODMAPs in grains?

Without delving into too much detail here, the answer is – possibly.  While the evidence for commercial ‘digestive enzyme’ supplements is poor, recent research from Monash University (8) has shed light on the usefulness of specific alpha-galactosidase enzyme tablets, for the digestion of GOS sugars.

It’s important to note that most whole grain breads and cereals contain both GOS and fructans in high levels.  So mitigating the effect of the GOS by taking these enzymes may, or may not be enough to allow individuals to tolerate these foods.

 

Marnie is an Accredited Practising Dietitian consulting at Everyday Nutrition in Melbourne’s Eastern suburbs.  She has recently completed Monash FODMAP training, and has over 10 years experience using the diet with clients in private practice.  Marnie specialises in gastrointestinal nutrition, IBS and food intolerance. www.everydaynutrition.com.au.

 

References;

  1. Role of FODMAPs in Patients With Irritable Bowel Syndrome. Mansueto et al, Nutrition in Clinical Practice Volume. Volume 30, Number 5. 665–682, 2015.
  2. Innovative analytical tools to characterize prebiotic carbohydrates of functional food interest. Corradini et al. Anal Bioanal Chem. 2013;405:4591-4605.
  3. Staudacher HM, Whelan K The low FODMAP diet: recent advances in understanding its mechanisms and efficacy in IBS Gut 2017;66:1517-1527.
  4. De Giorgio R, Volta U, Gibson PR Sensitivity to wheat, gluten and FODMAPs in IBS: facts or fiction? Gut 2016;65:169-178.
  5. Whole grain consumption and risk of cardiovascular disease, cancer, and all cause and cause speci c mortality: systematic review and dose-response meta-analysis of prospective studies. Dagfinn et al. BMJ 2016;353:i2716
  6. Whole grain consumption and risk of cardiovascular disease, cancer, and all cause and cause speci c mortality: systematic review and dose-response meta-analysis of prospective studies. Dagfinn et al. BMJ 2016;353:i2716
  7. Addressing the Role of Food in Irritable Bowel Syndrome Symptom Management. Capili et al. J Nurse Pract. 2016 May; 12(5): 324–329.
  8. Tuck CJ, Taylor KM, Gibson PR, Barrett JB, Muir JG. Increasing Symptoms in Irritable Bowel Symptoms With Ingestion of Galacto-Oligosaccharides Are Mitigated by [alpha]-Galactosidase Treatment. Am J Gastroenterol. 2017.

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