According to the International Foundation for Functional Gastrointestinal Disorders, Irritable Bowel Syndrome (IBS) affects between 10%-15% of the population worldwide. IBS is a chronic, difficult to treat, disorder that affects interactions between the brain, gut, and nervous system. Some people experience mild symptoms while others experience debilitating symptoms.
IBS may present with the following symptoms:
- Moderate to severe abdominal pain
- Infrequent bowel movements/strained stooling
- Runny stools/diarrhea
Diet & IBS Symptoms
General food-related recommendation for people with IBS include limiting fat, caffeine, alcohol, and fiber intake. However, more research is showing that following a low FODMAP Diet can reduce uncomfortable symptoms of IBS. Great! But what is the FODMAP diet…?
A low FODMAP Diet reduces the consumption of fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP). These carbohydrates can pass through the small intestine (without being absorbed) and head directly into the colon. In the colon, they are fermented by bacteria, causing gas and bloating. FODMAPs are also osmotically active, which means that they draw water into the colon, which can cause diarrhea.
Research studies show an association between following a low FODMAP Diet and a reduction in IBS symptoms. In a study published in 2011, participants on a low FODMAP Diet vs. a regular diet, experienced a reduction in bloating, abdominal pain, flatulence, and diarrhea.
The catch, however, (which seems fairly obvious) is that the participants only saw an improvement in symptoms if they strictly followed the low FODMAP diet. A strict diet regimen presents challenges with compliance and requires participants to be motivated and have the resources required (time, funds, knowledge) to follow the diet (1).
Fiber & IBS
Fiber is a type of carbohydrate that cannot be broken down and absorbed. It has multiple benefits, including helping us feel full for longer by slowing down digestion, cleaning out our colons, reducing our blood sugar levels, and reducing cholesterol levels in our bodies. Bottom line: fiber is super important! There are two types of fiber, soluble and insoluble, and both have different impacts on digestion. Soluble fiber absorbs water, whereas insoluble fiber does not (3).
Depending on what is happening in your gut, you may want to focus on eating certain types of fiber. For example, if you’re having runny stools, you’ll want to try eating soluble fiber to soak up the water and bulk up your stools. However, if you’re feeling constipated, eating insoluble fiber may make your symptoms worsen.
Foods with soluble fiber: nuts, blueberries, psyllium (fiber supplement)
Foods with insoluble fiber: seeds, fruit skins, whole grains (gluten-free for low FODMAP!)
High FODMAPs foods to avoid
- Grain: Wheat, rye, barley
- Veggies: Sweet potatoes, mushrooms, cauliflower, snow pears, onion, asparagus, snap peas, brussel sprouts, garlic, artichokes, leeks, beetroot, cabbage, beetroot, peas
- Fruit: Apples, pears, apricots, blackberries, plums, mango, cherries, watermelon, peaches, prunes, nectarines, and most dried fruit
- Dairy: cows/goat milk, yogurt
- Legumes: Red kidney beans, baked beans, soya beans
- Sweeteners: honey, sugar alcohols (mannitol, sorbitol), high-fructose corn syrup
Low FODMAPs alternatives to try
- Grain: wheat-free grains/flour, gluten-free bread or cereal products, quinoa
- Veggies: bok choy, green beans, parsnip, cucumber, carrots, celery, eggplant, lettuce, potatoes, yams, tomatoes, zucchini,
- Fruit: Banana, grapes, most berries (except boysenberries and blackberries), lemon, lime, mandarin oranges, kiwi, pineapple, passion fruit, rhubarb, honeydew, melon
- Dairy: lactose-free milk, almond milk, hard cheeses, feta, cottage cheese
- Sweeteners: maple syrup, sugar (sucrose)
What to do if you suspect you have IBS?
My personal recommendation is to keep a food diary for an entire week, and write down all the foods that cause your symptoms to flare up. If you’re noticing a pattern with certain types of foods, avoid them moving forward. IBS can present in the form of constipation or diarrhea, which I didn’t even know until a few weeks ago, so be aware of that.
Based on what I’ve learned from friends who have IBS, they didn’t realize how bad their symptoms were until they changed their diets and started to feel better. The sooner you can identify any potential trigger foods, the better you’ll feel moving forward 🙂
** A special thank you to Joanne for her work pulling the research articles that I references in this post!
- Comparison of symptom response for low FODMAP vs stadard in patients with IBS, Staudacher et al. (2011)
- Efficacy of the low FODMAP diet for treating irritable bowel syndrome: the evidence to date, Nanayakkara et al (2015)