For the clinical features and diagnosis of irritable bowel syndrome (IBS), please see the following article on this website:
For an overview of the management of irritable bowel syndrome (IBS), please see the following article on this website:
A trial of a low FODMAP diet is recommended primarily for persons with irritable bowel syndrome (Moayyedi et al., 2019). It is also used in some patients with inflammatory bowel disease, celiac disease, or small intestinal bowel overgrowth (Eswaran, 2021).
FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, polyols. FODMAPs are short-chain carbohydrates that are easily fermented by bacteria in the colon, leading to excessive production of gas and increased secretion of water into the gastrointestinal tract (Eswaran et al., 2021; Lacy et al., 2021). This is why in many persons with irritable bowel syndrome, certain high FODMAP foods can cause (Eswaran et al., 2021):
– Distension of the lumen of the intestine, feeling of bloating, excessive belching and flatulence
– Abdominal cramping and pain
– Change in bowel habits.
Does a low FODMAP diet work?
Yes, it does work for many patients with irritable bowel syndrome and is clearly recommended by American and Canadian clinical practice guidelines (Lacy et al., 2021; Moayyedi).
In most (though not all) of the randomized, controlled clinical trials, a low FODMAP diet was associated with a significant reduction in the symptoms of irritable bowel syndrome (Lacy et al., 2021). It is particularly likely to help with abdominal pain and bloating.
Two important things before starting
1. It may seem like the low FODMAP diet is too difficult for most people to do. But, we must emphasize to patients that complete elimination of high FODMAP foods needs to be done for only 2 to 4 weeks.
After that, those foods will quickly be introduced one by one. In the end, only SOME high FODMAP foods, identified as particularly causing symptoms for that particular person will need to be avoided or minimized long term. The other high FODMAP foods that were initially eliminated can be resumed.
2. Patients should be asked to keep records in a diary before starting the low FODMAP diet and throughout the several weeks of eliminating and reintroducing foods. The diary should include information about:
– Food eaten, including brand if applicable
– Cooking methods
– Quantity consumed
– Symptoms of irritable bowel syndrome
Implementation of the low FODMAP diet
Stage 1: Elimination of all high FODMAP foods
The patient is asked to only eat low FODMAP foods. Improvement in symptoms of irritable bowel syndrome is expected in about 2 to 6 weeks (Lacy et al., 2021).
Stage 2: Reintroduction of the eliminated foods, one by one
The high FODMAP foods that were eliminated are gradually reintroduced one by one while carefully watching for any recurrence of the symptoms of irritable bowel syndrome. A new high FODMAP food can be introduced about every 3 days or so.
Stage 3: Development of diet plan for that particular person
Based on the observations from Stage 2, the person should adopt a diet that excludes foods that triggered symptoms. The person would then continue on this diet long-term.
If at all possible, the diet should be developed and followed with the help of a dietician with experience with irritable bowel syndrome. If this is not possible, then good educational material should be provided to allow the patient and family to implement the diet on their own (Lacy et al., 2021).
We, as mental health clinicians, can provide support to these patients while they go through this process. Also, persons with eating disorders tend to use various diets inappropriately. One of our Members wrote to me that she has seen many patients with an eating disorder who were following a low FODMAP diet. This is another reason why mental health clinicians need to know about the low FODMAP diet so that we can correctly advise patients with eating disorders about what it is for and how long it needs to be done.
A list of the foods that are and are not allowed during the stage of strict elimination of high FODMAP foods is given below and is available at the American College of Gastroenterology’s website at this link. Sources: Eswaran (2021), Shephard et al. (2013).
Foods to avoid during the 2- to 4-week strict low FODMAP period
Lactose: milk and other lactose-containing products. Includes brie, cottage cheese, ice cream, ricotta, sour cream, whipped cream, etc.
Also, coconut milk and soy milk should be avoided. Almond milk is allowed.
Cereals: anything made with wheat, barley, or rye.
– Beans (including green beans, kidney beans, lima beans, pinto beans, yellow beans)
– Peas (including black-eyed peas, chickpeas, hummus)
– Soy products
Some vegetables: artichokes, asparagus, broccoli, brussels sprouts, cabbage, cauliflower, garlic, green beans, mushrooms, onions, snow peas sprouts, summer squash.
Many fruits (alphabetically): apples, apricots, avocados (yes, avocados are technically fruits), cherries, dates, guavas, honeydew melon, lychee, mandarin oranges, mangoes, nectarines, peaches, persimmons, pears, plums, star fruit, watermelon.
Also, dried fruits, less ripe fruits, canned fruit in natural juices.
And, also, fruit pastes (chutney, plum sauce, barbeque sauce, ketchup),
Sweeteners: high fructose corn syrup, honey agave, hydrogenated starch, isomaltose, malitol, mannitol, polydextrose, sorbitol, xylitol.
Beverages: beer, rosé wine, port, sherry
Foods that we are not sure need to be avoided
Foods allowed in the 2- to 4-week strict low FODMAP period
Cereals: corn, rice, oats, quinoa.
So, products made of these cereals are allowed, for example, corn bread, corn flakes, oatmeal, gluten-free bread, gluten-free pasta, potato-based bread, rice-based noodles, rice-based bread, wheat-free rye bread
Vegetables: bean sprouts, bell peppers, bok choy, carrots, celery, chives, cucumbers, eggplant (called brinjal in some countries), kale, lettuce, potatoes, pumpkin, radishes, spinach, tomatoes, turnips, winter squash, yams, and zucchini.
Fruits: blackberries, blueberries, boysenberries, cantaloupe, cranberries, grapefruit, honeydew, kiwis, kumquats, lemons, limes, passion fruit, raspberries, strawberries
The following fruits are allowed in limited quantities: grapes, oranges, papaya, pineapples, watermelon.
Milk alternatives: Lactose-free (Lactaid®) milk, almond milk (and almond butter), cashew milk, rice milk
The following milk-based products are allowed—though in limited quantities—because they contain lesser amounts of lactose: butter, half and half, margarine, sour cream
Yogurt alternatives: lactose-free yogurts, Greek yogurt
Ice cream alternatives: gelato or sorbet (in limited amounts due to the fructose content)
Some cheeses: Camembert, Colby
The following cheeses are allowed in limited quantities: cream cheese, goat cheese, feta cheese, cheddar, parmesan, mozzarella, Swiss cheese
Sweeteners: aspartame, maple syrup, jams, marmalades, saccharin, sucralose, sugar (table sugar)
Vegemite (an Australian food spread)
Optional to read:
As far as is known, the low FODMAP diet does not have significant side effects except that if FODMAPs are overly restricted for a long period of time, micronutrient deficiencies can occur (Eswaran et al., 2020; Staudacher et al., 2020). It is not known whether the low FODMAP diet could lead to any unintended effects on the gut microbiome (Lacy et al., 2021).
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