Living with Irritable Bowel Syndrome (IBS) is more than just the occasional tummy ache or rush to the bathroom. IBS can mean debilitating, unpredictable and sometimes daily symptoms of gas, bloating, cramping, constipation and diarrhoea. While no one knows what causes IBS and there is currently no known cure, the good news is it can be well managed with a low FODMAP diet.
FODMAP is an acronym for four groups of short chain carbohydrates, or sugar molecules found naturally a variety of fruits, vegetables, grains, legumes and dairy products (e.g. lactose intolerance). When we consume FODMAPs in food or drinks they are not absorbed properly in the small intestine. This means they stay in the intestines and continue to pass through to the large intestine, or colon, before leaving the body and being flushed away. As FODMAPs pass through the large intestine, two processes that can occur may trigger digestive symptoms in certain people:
1. FODMAPs are highly osmotic (they draw water into the intestine). Having extra water drawn into the intestines creates pressure in the gut and often causes loose or watery bowel motions (diarrhoea).
2. FODMAPs are fermentable When passing through the large intestine, the bacteria that make up your gut microbiome ferment them creating large volumes of gas. This gas then pushes on the walls of the intestine and for those with sensitive nerve endings in the gut (i.e. people with IBS) this stimulates the gut brain axis into gear resulting in pain, abdominal distention, bloating and embarrassing wind.
Research shows that a low FODMAP diet can help about 3 out of 4 people gain significant and consistent relief of their IBS symptoms by following a diet low in FODMAPs.
F – Fermentable by the healthy bacteria that naturally live in the large intestine
O – Oligosaccharides (fructans & GOS) found wheat, onion, garlic, nuts and legumes
D – Disaccharides (lactose) found in milk, yoghurt, ice cream custard and some “wet” cheese e.g. ricotta. Note most hard cheese and butter is naturally lactose free
M – Monosaccharides (excess fructose) found in apples, pears, stone fruit, honey and high fructose corn syrup
A – And
P – Polyols (sorbitol & mannitol) found in cauliflower, mushrooms, watermelon, apples, stone fruit and some artificial sweeteners
There are two things about the FODMAP diet that it’s important to know:
1. The fermentation process is normal and it actually helps to keep your gut and gut microbiome healthy and nourished.
2. Not everyone is sensitive to all four FODMAP groups.
This means that going on a FODMAP diet and staying on it forever is unnecessarily over restrictive for many people and it may be detrimental to gut microbiome and gut health. For this reason the FODMAP diet is designed to be implemented in 3 phases that are designed to give you maximum food variety and minimal gut upset.
Phase 1 – Low FODMAP phase: This phase lasts 2-6 weeks. During this time, you will avoid foods high in all FODMAP groups, so that we can assess your overall response to restriction.
Phase 2 – Re-challenge phase: During the re-challenge phase, your dietitian will guide you through FODMAP challenges to help you determine your level of sensitivity to the different FODMAP sugars. This phase needs to be well structured and challenge foods need to be chosen carefully to help you get clear results.
Phase 3 – Modified low FODMAP diet: Once you know your trigger FODMAPs and level of sensitivity, your dietitian can help you to reintroduce some high and moderate FODMAP foods. This stage is important, to ensure that your diet is balanced in the long term for optimal health, wellbeing and of course to keep your gut healthy!
You can read more about the three phases of the low FODMAP diet here. If you think the low FODMAP diet may be for you, start by seeing your doctor and confirm that your symptoms are IBS and not something else. Once you’ve done this, we recommend seeing a FODMAP trained Registered Dietitian to get a plan personalised to your needs and situation.