The Lowdown on the Low Fodmaps Diet to Improve Gut Symptoms

Most people experiencing excessive gas, bloating, abdominal pain and altered bowel movements (diarrhoea and/or constipation) would have heard of the Low FODMAPs diet by now. Many GP’s and health practitioners are regarding it to be one of the best investigative diets for identifying problematic foods. Research shows that people with Irritable Bowel Syndrome (IBS) and Inflammatory Bowel Disease (IBD) can significantly improve symptoms by managing the amount of FODMAPs in their diet.

What are FODMAPS?

FODMAPs is an acronym for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols.

Essentially, FODMAPs are short-chain carbohydrates (sugars, starches and fibres), which can be poorly digested and absorbed in the small intestine, resulting in movement through to the large intestine. Here, they can be fermented / digested by the millions of bacteria that reside there, producing carbon dioxide, hydrogen, and/or methane gasses.

Due to their small molecular size, some FODMAPs can also result in an osmotic effect, where water is drawn into the bowel – just like water is drawn to large concentrations of salt (think back to chemistry days at school). You can picture what happens when excessive water and/or gas is in the bowel.

Which foods contain FODMAPs?

FODMAPs can be found in many foods, mostly of plant origin, with the exception of lactose. Some food examples are below, but a dietitian experienced with this diet will be able to provide a more extensive list:
Fructose: apples, pears, mango, honey, asparagus, cherries
Fructans: garlic, onions, leeks, wheat, rye,
Lactose: milk, cream, yogurt, soft cheese e.g. ricotta
GOS: legumes e.g. chickpeas, kidney beans
Polyols: apricots, avocado, cherries, mushrooms, sugar alcohols like sorbitol and mannitol

For most people, eating FODMAPs is not a big deal – perhaps a feeling of fullness after eating and normal passing of gas. But for people with a sensitive and irritable gut, it can be problematic.

  • There are a number of reasons why some people experience more issues with FODMAPs than others including:
    being more sensitive to gas production, potentially due to more nerves in the gut, which can not only result in feelings of pain and discomfort but also affect bowel motions by stimulating faster motility (causing diarrhoea) or slowing gut muscles down (causing constipation);
  • Reduced production of enzymes in the small intestine that are responsible for breaking FODMAPs down for absorption (e.g. people with lactose intolerance have a lower production of the lactase enzyme);
  • Reduced capacity to transport some FODMAPS across the gut wall.

These factors can explain why there is such a strong dose-response relationship, meaning that small amounts of these foods are often tolerated, but larger amounts cause symptoms.

This is not only the case for IBS-sufferers though – all humans don’t have the enzymes to break down fructans or GOS. Polyols are also incompletely absorbed among humans. Therefore, these FODMAPs provide valuable food for gut bacteria.

Glucose also helps with the absorption of fructose, and it’s estimated that approximately 35% of the population who eats a large amount of high-fructose foods ‘in excess’ of glucose, will have fructose malabsorption.

With all this talk about FODMAPs being problematic for some people, it’s important to know that fuelling and keeping our healthy gut bacteria alive is of high importance for our health and well-being. Healthy bacteria produce short-chain fatty acids responsible for gut health and preventing colon cancer.

Increasing amounts of research link a healthy gut to preventing chronic diseases, improved mental health, weight management and much more.

The aim of reducing FODMAPs in someone’s diet is to manage difficult symptoms but keeping as many FODMAPS in the diet as tolerated – it’s not advised to restrict FODMAPs among people without gut symptoms.

The Low FODMAPs diet

The researchers at Monash University are responsible for ongoing research on FODMAPs. Their low-FODMAP diet is designed as a 2-6 week opportunity to cut out high-FODMAP foods from the diet to see if symptoms improve. A systematic food challenge process then aims to identify which of the FODMAP categories are problematic (it’s not expected that everyone will react to all FODMAPs).

The best way to undertake any diet change and challenge process is to seek support from an Accredited Dietitian experienced in the area of gut issues.

A knowledgeable dietitian will be able to provide you with all the information and support you need to get you to the point of broadening your diet as soon as possible. It is also important to have them assess whether you may benefit from a different investigative diet (e.g. for food chemical intolerance), and/or whether the additional investigation of other possible triggers such as gluten or dairy proteins may be worthwhile. There are also a number of nutrients, probiotics and supplements that can be helpful in calming, healing and rejuvenating the gut if you’re looking for guidance beyond just an investigative diet.

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