Irritable Bowel Syndrome & FODMAPS
November 02, 2017
Irritable Bowel Syndrome & FODMAPS
Irritable bowel syndrome or IBS is thought to affect one in seven adults, making it one of the most common gut disorders. It is characterised by bloating, excessive gas, visible distension of the abdomen and alterations to bowel habits with either diarrhoea, constipation or a combination of both.
 
In the old days IBS was the label given when doctors could find nothing medically wrong to explain the symptoms. It was largely thought that stress and anxiety had a role to play, perhaps even be the cause, and patients were sent away with little to help them.
 
The idea that stress and anxiety are involved was not in fact wrong, as they very much can be part of the story. Just think about what happens when you’re nervous or excited about something – you often find yourself running to the loo and will almost certainly have butterflies in your stomach. This shows us that the hormones involved in the stress response affect the gut.
 
However, we now understand a lot more about what is going on with IBS. It is not just all in your head and there is much you can do to gain control of your symptoms.
 
 
See Your Doctor
 
It’s vitally important that you don’t self-diagnose IBS. Your first step if you haven’t already done so, if to see your GP who will likely refer you to a gastroenterologist for further testing.
 
The symptoms of IBS can be common to a number of different, serious bowel disorders, including inflammatory bowel disease, coeliac disease and bowel cancer. These must be ruled out first before a diagnosis of IBS.
 
 
What are FODMAPs?
 
In recent years researchers have identified a group of short chain carbohydrates that are key in producing the symptoms of IBS in most patients. These are collectively called FODMAPs, which stands for Fermentable, Oligo-saccharides, Di-saccharides, Mono-saccharides And Polyols.  
 
These carbohydrates are types of sugars that occur widely in healthy foods, but they cause problems in some people. They are poorly absorbed in the small intestine and so enter the colon where they are rapidly fermented by the resident gut bacteria – your microbiota.
 
 
How do FODMAPs cause IBS symptoms?
 
Fermentation is generally a good thing and essential for the health of the bowel. In fact, many of the products of fermentation, particularly short chain fatty acids such as butyrate, are key in maintaining our physical and mental health. However, the other product of fermentation is gas.
 
If the production of gas is excessive, or that gas becomes trapped due to constipation, the result is pain, bloating, flatulence and discomfort.
 
Interestingly, it may also come down to our perception of pain in the gut. It seems that some people with IBS have a hypersensitive gut. The same amount of gas may be produced in two people, yet only be perceived as uncomfortable and painful in the one with IBS.

"It seems that some people with IBS have a hypersensitive gut. The same amount of gas may be produced in two people, yet only be perceived as uncomfortable and painful in the one with IBS."

 
Some FODMAPs also tend to pull water into the bowel and this can result in diarrhoea, as well as contribute to bloating and discomfort.
 
Some people also have a flurry of bacteria growing in the wrong place. Most of our microbiota is found down at the latter part of the gastrointestinal tract, in the colon. But for several reasons these bacteria can migrate up into the small intestine. This is called ‘small intestinal bacterial overgrowth’ or SIBO for short.
 
The problem with SIBO is that the small intestine is a far narrower section of the bowel and if gas and excess fluid is found here, pain, discomfort and bloating is significant.
 
 
What foods are high in FODMAPs?
 
The four main groups of FODMAPS are:

1. Foods that contain much more fructose than glucose. This is because glucose helps with the absorption of fructose. While most of us can happily absorb fructose, it is estimated that 30-40% of people do not resulting in a fructose party in the colon for the microbiota! Foods that contain fructose in excess of glucose include asparagus, artichokes, sugar snap peas, apples, figs, cherries, mango, pears, watermelon, honey and many fruit juices.

2. Foods that contain lactose. Some people continue to produce the enzyme lactase required to break down the milk sugar lactose. However, many people don’t and this means that lactose becomes fuel for the microbiota. Most people with lactose malabsorption can tolerate small amounts, but exceed this threshold and symptoms result. Foods high in lactose include milk soft cheese such as ricotta and cottage, custard and ice cream. Yoghurt has already been fermented to some degree and tends therefore to have lower lactose levels, however this does depend on the yoghurt.

3. Foods that contain sugar polyols including sorbitol, zylitol and mannitol. These occur naturally in foods such as apples, apricots, nashi pears and stone fruits. However, they are also often used in sugar free products such as chewing gum, sugar-free mints and sugar-free bakery products.

4. Foods that contain fructans and galacto-oligosaccharides (GOS). These are short chain carbohydrates found in barley, wheat and rye; veggies including garlic, onions, legumes and artichokes; fruits including nectarines, custard apple, watermelon and persimmon; chicory based drinks; and products where inulin has been added as a fibre/prebiotic (e.g. many yoghurts and muesli bars). There are also a list of veggies and fruits with a more moderate content of fructans or GOS. These may only be problematic if consumed in excess.
 

Oils, including extra virgin olive oil, do not contain FODMAPs. Cobram Estate also make a range of infused oils and these have all been certified as FODMAPs friendly. These include a roast onion infused oil and a garlic infused oil – brilliant for using on a low FODMAPs diet to give the flavour without the problem FODMAPs of the whole foods.
 
 

What is a low FODMAP diet?
 
Researchers at Monash University are at the forefront of treating IBS with a diet they designed to be low in these FODMAPs. They have found roughly 7 out of 10 patients with IBS achieve good symptomatic relief with a low FODMAP diet.
 
An important point to make is that many IBS sufferers have tried a gluten free diet and reported an improvement, but some ongoing problems. The Monash team have shown that it is not gluten that is the problem at all. Rather by cutting out gluten containing foods, such as wheat, they inadvertently also reduced their load of fructans and other FODMAPs. The ongoing problems are as a result of other FODMAPs still present in fruits, veggies and other plant foods that are gluten free.

"The Monash team have shown that it is not gluten that is the problem at all. Rather by cutting out gluten containing foods, such as wheat, they inadvertently also reduced their load of fructans and other FODMAPs."

 
If you have a diagnosis of IBS it is well worth trying a low FODMAP diet. However, this is best done with the help of a dietitian experienced with this approach. It is not intended as a diet for life and in fact may be detrimental if followed for too long.

"If you have a diagnosis of IBS it is well worth trying a low FODMAP diet. However, this is best done with the help of a dietitian experienced with this approach. It is not intended as a diet for life and in fact may be detrimental if followed for too long."

 
Most of the foods containing FODMAPs are healthy foods and importantly FODMAPs are prebiotics, supporting the growth of a diverse and balanced microbiota. Cut them our forever and there may be damaging consequences for the microbiome and in turn our own health.
 
A dietitian will help you to make the appropriate food swaps to ensure you have a healthy balanced diet while you aim to get symptoms under control. He or she will then devise a strategy for reintroducing FODMAP containing foods into your diet. To many of these you may find you build a tolerance as your gut and your gut bugs adapt, while others may continue to be triggers. The goal is to end up with a much smaller list of foods you need to avoid, and in some cases, there may be none at all.
 
 
Where do I seek help?
 
You’ll find an Accredited Practising Dietitian on the Dietitians Association of Australia website
 
Monash University have an excellent low FODMAPs App to help and you can send your symptom reports and food diary directly to your dietitian. Find out more here.  
 
 
 

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