Low-FODMAP Diet for IBS

Amy was an old college friend, trying to be “healthy” by eating those low-sugar diabetic candies that were mainstream during the low-carb craze. Since she thought they were healthy, she ended up eating an entire bag…right before a first date. 

Little did she know that many diabetic candies contain sugar alcohols, such as mannitol. These cause extreme gas, bloating, and diarrhea. She didn’t get asked out on a second date, but she did learn her lesson.

Amy may or may not have been suffering from IBS at the time but she did get a taste of a FODMAP food side effect.  

What’s the Low-FODMAP Diet?


FODMAP stands for: fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. Basically these are types of short-chain carbohydrates or sugars that are found in food. 


  • Oligosaccharides: include fructans (fructo-oligosaccharides or FOS) which are short chains of sugar. Humans lack an enzyme to break these down which can lead to troublesome symptoms for IBS.
  • Disaccharides: lactose is sugar found in milk, that’s made of two units. It needs to be broken down into single units by the enzyme lactase so it can be absorbed. People who lack this enzyme may have difficulty digesting it.
  • Polyols: are sugar alcohols such as sorbitol and mannitol. Only about one-third of what is consumed is absorbed so the rest may cause digestive upset.
  • Fructose: in small amounts, the simple sugar doesn’t require digestion. But if glucose is present in equal or greater amounts, or if someone is experiencing fructose malabsorption (about 30-40% of individuals have this) discomfort may occur [1].


When you have too many of these foods or if you have a compromised gut, such as with IBD or IBS, the foods may become fermented by gut bacteria. Some gut fermentation is normal but excess may cause gas and bloating. 

These types of carbohydrates are also osmotic, meaning they bring water into your intestinal tract. The excess water causes your bowel movements to be loose and more liquid, leading to symptoms such as diarrhea.


The low-FODMAP diet has two phases. The first phase involves a strict reduction of all dietary FODMAPs. This typically lasts for four to six weeks. Phase two is a reintroduction of specific FODMAPs depending on personal tolerance. 


FODMAPs in the diet include:

  • Fructose: fruit, honey, high fructose corn syrup
  • Lactose: dairy (milk, cheese, yogurt)
  • Fructans (inulin): wheat, onion, and garlic
  • Galactans: beans, lentils, legumes 
  • Polyols: sweeteners such as sorbitol, mannitol, xylitol, maltitol, and stone fruits, such as avocado, apricots, cherries, nectarines, peaches, and plums [2]


Observational studies have shown that the restriction of FODMAP foods in the diet can alleviate some gastrointestinal symptoms in patients with IBD. But to date, few studies have evaluated the efficacy of a low-FODMAP diet for treating IBS and other gastrointestinal symptoms [3].


Avoiding FODMAPs doesn’t help everyone. But in a study published in the journal Gastroenterology, about 3 out of 4 people with IBS had their symptoms ease right away after starting a low-FODMAP diet and felt the most relief after 7 days or more on the plan.” – WebMD [4]


Keep in mind that not everyone responds well to the low-FODMAP diet and if you suffer from IBD, you may need to practice more caution when it comes to food sensitivities or reactions. The process of the low-FODMAP diet is extensive, taking up to six months, as it takes time for the gut to heal. 

Since the low-FODMAP diet is restrictive, we recommended trying it with the guidance of an experienced dietitian or physician [3]. A dietitian can also prevent nutrient deficiencies that may result from a restricted diet. 

Many of the restricted foods on the low-FODMAP diet are healthy. They contain prebiotics that promote more healthy bacteria in your gut. The low-FODMAP foods are also high in many nutrients. This is why it’s important to weigh the pros and cons before eliminating entire food groups from your diet.


How to Eat Low-FODMAP

If you experience gas, bloating, pain, diarrhea, or constipation it may be worth considering the low-FODMAP diet. It may be worth eliminating these foods for four weeks and see if symptoms get better. 

One of the best ways to make a change in your diet is to replace the foods that are bothersome, with other healthy options. 


Avoid these foods:

  • Grains: wheat (breads, cereal, pasta), bran, barley, rye, spelt, pastries, cereals
  • Protein: sausages, processed meats, beans (black, kidney, lima, etc)
  • Fats: avocado, hummus, tzatziki
  • Dairy: cream, yogurt, ice cream, buttermilk, sour cream, cream cheese, ricotta
  • Fruits: apple, apricot, avocado, watermelon, mango, peaches, ripe banana, raisins, pears
  • Vegetables: garlic, onion, asparagus, cauliflower, mushrooms, peas
  • Nuts and seeds: cashews, pistachios, more than 10-15 of almonds or pecans 

Eat these foods:

  • Grains: rice, oats, quinoa, gluten free bread, buckwheat, cornflour
  • Protein: chicken, eggs, pork, fish, beef, fermented tofu, 
  • Fats: olive oil, coconut oil
  • Dairy: lactose-free milk products, cheddar cheese, parmesan cheese, dairy alternatives including almond milk, coconut milk, hemp milk.
  • Fruits: unripe banana, blueberries, kiwi, blueberries, grapes, orange, strawberry, pineapple
  • Vegetables: bell pepper, carrots, bok choy, eggplant, tomatoes, spinach, zucchini, kale, green beans, lettuce (arugula, butter, iceberg), squash, pumpkin
  • Nuts and seeds: chestnuts, hazelnuts, peanuts, pumpkin seeds, sesame seeds, pine nuts


Keep in mind that many of these foods may be appropriate for inflammatory bowel disease

Since the FODMAP diet is quite restrictive, it takes a bit of extra creativity to find meals that taste good. Even if you can’t have garlic or onion, you can focus on seasonings such as mustard, pepper, turmeric, ginger, and chives to spice up your meals. 

For more recipe suggestions, meal ideas, and healthy lifestyle support, start a conversation with Nori Health.


This article has been written by Lisa Booth, registered dietitian and nutritionist, and co-founder of Nori Health. Content is based on her professional knowledge, and our collection of 100+ scientific research study papers.