What is The Low Fodmap Diet?
Written by Erica Gittleson, RD, medically reviewed and edited by Dr. Bojana Jankovic Weatherly.
FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. These are short-chain carbohydrates (sugars) that the small intestine absorbs poorly. Some people experience digestive distress after eating them. Symptoms can range from cramping, diarrhea, gas, bloating, and constipation. Patients with a diagnosis of IBS (irritable bowel syndrome) or SIBO (small intestinal bacterial overgrowth) might be put on this diet to help reduce symptoms and determine food triggers as research has shown a drastic improvement in symptoms when following this diet. This diet, like most elimination diets, is meant to be temporary. For more information on elimination diets refer to our article Elimination Diet 101 – Dr. Bojana (drbojana.com). For more information on low FODMAP diet resources and how it is applicable to SIBO, see this article.
Why is it necessary to reintroduce?
Many of our patients ask if it’s necessary to reintroduce foods, as they may be feeling better, and their symptoms are under control. Some fear that their symptoms will come back once they start reintroducing. Here are a few reasons why it is highly recommended to move through the challenges:
- You will have more freedom. Most people find out that they can tolerate several FODMAP groups, making it easier to eat out. You will feel a lot less restricted and isolated and have more food freedom when cooking at home or eating out.
- It increases the variety of your diet. The low FODMAP diet is a very restrictive diet. If you stay in the elimination phase, you might be unnecessarily restricting yourself and keeping important nutrients from your body.
- Some foods that are high in FODMAPs such as fermented foods and other foods rich in prebiotics help the growth of good bacteria in your gut.
- If you eliminate foods for a long period of time and try to re-introduce them, there is a chance you may not tolerate them or may develop allergies to them.
What is the reintroduction phase?
According to Monash University, the creators of the low fodmap diet, if you’ve been following a low fodmap diet for 2-6 weeks and your IBS symptoms are under control or reduced to a minimum, this means, it’s time to start reintroducing high fodmap foods. The reintroduction phase is the second phase of the low FODMAP diet, also known as the challenge phase. The goal of this phase is to find out which FODMAP groups trigger your IBS symptoms. To do this, we start by testing the different FODMAP groups through food tests.
There are 6 FODMAP groups: fructose, lactose, sorbitol, mannitol, fructans and galactans (GOS). In each test, you test one of these groups. Each test consists of 3 testing days and on every testing day you test a larger amount of a test food. During each test, you monitor your symptoms, allowing you to find out how you react to each of the FODMAP groups. Patients are advised to monitor symptoms by keeping a food and symptom diary (the Monash University Fodmap app has one that you can use).
At the end of the reintroduction phase, you will know which FODMAP groups you don’t tolerate, which you tolerate in small amounts, and which groups you can eat freely. After this phase you can start modifying your diet or work with your practitioner to help you.
How long does the reintroduction phase take?
Monash university recommends the reintroduction phase take 6 to 8 weeks. They recommend 9 different tests, for the most part each test will take about a week. However, some tests can take longer if the person experiences symptoms. During those periods it’s important to pause testing until symptoms resolve and the person is back at their baseline.
HOW TO DO FODMAP REINTRODUCTION?
There are two ways to do the FODMAP reintroduction:
- THREE TESTING DAYS IN A ROW
- Day 1: test day – small amount
- Day 2: test day – moderate amount
- Day 3: test day – large amount
- Day 4-6: rest day
With this testing method, you do three testing days in a row. On the first day, you start with a small amount, and you build this up to a large testing amount on day 3 (portions are suggested in the app).
This is the testing method that Monash University recommends because this will help you move through the tests as quickly as possible. It’s recommended to take 2-3 rest days after the 3 test days and again, if you have symptoms wait until they resolve to move forward.
- THREE TESTING DAYS WITH A REST DAY BETWEEN EACH TEST
- Day 1: test day – small amount
- Day 2: rest day
- Day 3: test day – moderate amount
- Day 4: rest day
- Day 5: test day – large amount
- Day 6-8: rest day
With the second method, you do one testing day and then a rest day. Another testing day and a rest day again etc. This way of testing takes a little longer, but you might prefer this method if you know it generally takes longer for your symptoms to show up or feel more secure having a rest day in between each test.
Which foods to use for the tests?
When picking testing foods, it is important that these foods only contain one of the FODMAP groups. Some foods contain a high amount of more than one FODMAP group and if you use one of those foods, you won’t know to which FODMAP group you react. Therefore, pick foods that contain only one FODMAP. After you finish the reintroduction phase, you can start testing foods that contain more than one FODMAP.
I recommend using the amounts stated in the Monash University FODMAP app. Because the app is always up-to-date and the app is made by the creators of the FODMAP diet.
You can find the recommended challenge foods by opening the app, click on diary, click the plus on the upper right side and then click the symbol with the apple and the arrow.
There you can select the FODMAP group and see which foods they recommend and their portion sizes. Below are a few options for each FODMAP group:
FRUCTOSE
Pick one of the foods below to test. Test the following amounts on day 1, 2 and 3:
- Honey: 1 1/2 tsp (10 g), 2 tsp (14 g) and 1 tbsp (28 g)
- Mango: 1/4 mango (52 g), 1/2 mango (104 g) and 1 mango (208 g)
- Orange juice: 2/3 cup (140 g), 3/4 cup (157 g) and 1 cup (201 g)
LACTOSE
Pick one of the foods below to test. Test the following amounts on day 1, 2 and 3:
- Yogurt: 1/2 tub AKA 3oz (85 g), 1 tub AKA 6oz (170 g) and 1 cup AKA 8oz (200 g)
- Milk: 1/4 cup (60 ml), 1/2 cup (125 ml) and 1 cup (250 ml)
MANNITOL
Pick one of the foods below to test. Test the following amounts on day 1, 2 and 3:
- Cauliflower: 2 small florets (17 g), 4 small florets (33 g) and 8 small florets (66 g)
- Sweet potato: 3/4 cup (105 g), 1 cup (140 g) and 1 1/2 cup (210 g)
SORBITOL
Pick one of the foods below to test. Test the following amounts on day 1, 2 and 3:
- Avocado: 1/4 small avocado (40 g), 1/2 avocado (80 g) and 3/4 avocado (120 g)
- Blackberries: 2-3 berries (13 g), 5 berries (25 g) and 10 berries (50 g)
FRUCTAN – GARLIC
Garlic is tested separately in the fructans test. Test garlic in the following amounts on day 1, 2 and 3:
- Garlic: 1/4 clove, 1/2 clove, 1 whole clove
FRUCTAN – ONION
Onion is tested separately in the fructans test. Test one of these options on day 1, 2 and 3:
- Onion (red or white): 1/8 onion (11 g), 1/4 onion (22 g) and 1/2 onion (44 g)
FRUCTAN – GRAIN
Grains are tested separately in the fructans test. Test one of these options on day 1, 2 and 3:
- Wholegrain wheat bread: 1 slice (26 g), 1 1/2 slices (39 g) and 2 slices (52 g)
- Wheat pasta: 2/3 cup (100 g), 1 cup (150 g), 1 1/2 cup (220 g) (cooked weight)
FRUCTAN – VEGETABLE AND FRUITS
Monash also recommends to test a fructan vegetable or fruit. Test one of these options on day 1, 2 and 3:
- Raisins: 1 1/2 tbsp (19 g), 2 tbsp (26 g) and 3 tbsp (39 g)
- Grapefruit: 1/2 medium (104 g), 1 medium (207 g) and 1 large (280 g)
- Brussels sprouts: 3 sprouts (57 g), 4 sprouts (76 g) and 5 sprouts (95 g)
GALACTANS (GOS)
Pick one of the foods below to test. Test the following amounts on day 1, 2 and 3:
- Almonds: 15 nuts, 20 nuts and 30 nuts
- Canned chick peas, rinsed: 1/2 cup (84 g), 2/3 cup (112 g) and 1 cup (168 g)
Which group should I test first?
It doesn’t matter which group you test first. Most people start with the group that they are most curious about because they want to know if they can or cannot add that group back into their diet. There is no order that needs to be followed.
How to make your reintroduction a success?
- Make sure that you continue to eat strictly low FODMAP through the entire reintroduction phase. If you don’t do this, you can get symptoms, and this might interfere with your test results.
- Don’t add the FODMAP groups that you didn’t react to back into your diet until you have finished the reintroduction phase.
- Keep a food- and symptom diary to track how you are reacting to the different tests and to know when you are ready for the next one.
- Do the reintroduction phase under the guidance of a dietician, so you have somebody to help you interpret test results and symptoms.
- Wait until your symptoms have settled before you start a new test.
As with any reintroduction, it’s important to consult your Dietitian or Health Care Practitioner. If you have any questions about the low fodmap diet or how to properly reintroduce, reach out to us at BOJANA MD.
References:
1. https://www.karlijnskitchen.com/en/reintroduction-phase/
2. Low FODMAP Diet | IBS Research at Monash University – Monash Fodmap