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What are FODMAPs?
Fermentable oligosaccharides, disaccharides, monosaccharides and polyols, or FODMAPs, are specific carbohydrate chains found in various foods. These short carbohydrates can cause irritable bowel syndrome symptoms including bloating, abdominal pain and flatulence. The reason for these symptoms is that FODMAPs are poorly absorbed by the gut and instead are rapidly fermented by bacteria in the large intestine. FODMAPs are also osmotic, which means they draw extra water into the large intestine, leading to diarrhoea.
Sources of FODMAPs
Fermentable oligosaccharides, disaccharides, monosaccharides and polyols are found in a wide range of foods, such as:
- Oligosaccharides - onions, leeks, spring onions, garlic, artichokes, shallots, beetroot, peas, fennel, chicory, pistachio, legumes, cashews, lentils, chickpeas, wheat, barley and rye;
- Disaccharides - milk, yoghurt, custard and ice cream;
- Monosaccharides - apples, mangoes, pears, cherries, asparagus, watermelon, snow peas, high-fructose corn syrup, honey, and;
- Polyols - apples, pears, apricots, nectarines, peaches, plums, cherries, watermelon, cauliflower and artificially-sweetened chewing gum.
Alternative food sources
If you are experiencing symptoms including bloating, abdominal pain, flatulence and diarrhoea caused by FODMAPs, there are alternative foods for all food groups. Some alternatives may include:
- Fruits, including bananas, cantaloupe, grapes, lemons, limes, mandarins, oranges, passionfruit, raspberries, strawberries and blueberries;
- Vegetables, including potatoes, carrots, parsnips, zucchini, eggplant, capsicum, olives, lettuce, green beans, ginger, chili and chives;
- Breads and cereals, including corn, oats, polenta, quinoa, and rice;
- Protein sources, including fresh beef, chicken, lamb, pork and veal;
- Dairy products, including butter, lactose-free milk and yoghurt, rice milk, and;
- Other products including golden syrup, maple syrup and sucrose.
The low FODMAPs diet
Recent research has discovered the link between avoiding foods containing high amounts of FODMAPs and a decrease in gastrointestinal symptoms. It has been shown that up to 86% of people with irritable bowel syndrome showed an improvement in their symptoms, particularly bloating, when on a low FODMAPs diet, compared to a traditional diet for irritable bowel syndrome.  The low FODMAPs diet has also been shown to reduce symptoms in Crohn's disease and ulcerative colitis. The low FODMAPs diet can be done in consultation with a registered dietitian, so it is best to be referred to one by your doctor or specialist.
Carbohydrate absorption breath test
It is possible to test your ability to absorb certain carbohydrates using a breath test that measures the hydrogen and methane levels on your breath. This involves eating a low FODMAPs and low-fibre diet the day before, as well as fasting overnight. At the start of the test, the baseline breath sample will be taken. You will then be given a carbohydrate to consume (e.g. fructose) and regular breath samples will be taken to measure the levels of hydrogen and methane on your breath. If the levels of hydrogen and methane are high, this indicates that the carbohydrate is not being absorbed. This test can be used to check your ability to absorb the other types of carbohydrates.
FODMAPs reintroduction test
To reduce the symptoms caused by malabsorption of FODMAP carbohydrates, it is possible to trial a low FODMAPs diet. After a period of four weeks on a low FODMAPs diet, the different types of carbohydrates can be reintroduced one at a time to test your ability to absorb them. It is important to introduce foods that contain only one FODMAP carbohydrate, for example, milk for lactose, honey for fructose, mushrooms for mannitol and apricots for sorbitol. It is important to test the absorption of each carbohydrate to assess your tolerance. If there is no change in gastrointestinal symptoms, the carbohydrate can then be reintroduced into the diet.