1. It’s a life-long diet
This is perhaps the most common misconception: that you should follow a low FODMAP diet for the rest of your life. This is just a temporary, learning diet and the “low FODMAP” part refers to the first phase of the diet, when you eliminate all high FODMAP foods. As soon as symptoms are reduced and you feel better, you need to re-challenge those foods gradually and systematically to find out your personal triggers. You can then craft your personalized FODMAP diet. Even then, you are not done. As symptoms wax and wane, you are encouraged to re-challenge more foods every 3-6 months.
2. It’s the same for everyone
I often hear people tell me their doctor gave them a handout and told them to follow the low FODMAP diet. Period. It’s not that simple! This is not just a list of foods to avoid and foods to eat. Sure, a few foods have negligible amounts of FODMAPs and are “included” whereas other are high in FODMAPs and “excluded”, at least during the elimination phase. But so many foods are either low or high depending on their portion size. To complicate matters, there is the question of the FODMAP load in a single meal or snack. Most importantly, every person reacts to different foods and they will end up eating a modified FODMAP diet that is unique for them. This stresses the importance of securing the help of a registered dietitian who is knowledgeable in this topic to help navigate all its complexities.
3. It’s a gluten-free diet
It is not, as gluten is not a FODMAP. FODMAPs are carbohydrates and gluten is a protein. However, gluten and a certain class of FODMAPs (fructans) coexist in wheat, barley, and rye. This is where the confusion comes. Wheat, barley, and rye and products made with these grains are excluded during the first phase of the diet to eliminate the fructans. In fact, some low FODMAP foods that contain gluten, such as soy sauce, are included. On the other hand, not all gluten-free products are low FODMAP. Many gluten-free breads and other baked products often contain high-FODMAP ingredients such as honey, agave, pear or apple juice, or inulin/chicory, which makes them not suited for a low FODMAP diet.
4. It’s a lactose-free diet
Lactose is a FODMAP but the diet only needs to be low in lactose, not completely free of lactose. Lactose-free dairy products (milk, yogurt, cream cheese and ice cream) can be included. And so can those with minimal lactose content, for example hard cheeses like parmesan or cheddar, butter, and small amounts of cream and half-and-half.
5. It’s a low-fiber diet
Finally, some people think they need to avoid all high-fiber foods. This is not true and can be counterproductive for those suffering of constipation. Depending on which kind of motility issue you may have (diarrhea or constipation), the fiber content will need to be adjusted and the type of fiber individualized (more soluble or insoluble fiber). Low FODMAP sources of fiber such as permitted amounts of chickpeas and lentils, low FODMAP vegetables and fruits, and low FODMAP whole grains (quinoa, brown rice, millet, oats, etc.) can and should be included. See my article 5 Tips to Eat More Fiber on a Low FODMAP Diet for more ideas.