By Dr Jaci Barrett (Dietitian)
With the increasing amount of detail we share with you via our Monash University low FODMAP diet app, we are getting more and more questions about FODMAP stacking. Green foods on the app are low FODMAP and are therefore suitable on a low FODMAP diet, but more detail is provided in the app for some low FODMAP foods, where we reveal an upper limit serving size when the food then becomes red and therefore high FODMAP.
Broccoli and zucchini are good examples of this:
A standard serve of broccoli is ½ cup, which is low FODMAP and suitable for a low FODMAP diet. But you can see further details are given, revealing that large servings, >1 cup, contain high levels of the oligosaccharides and sorbitol.
For zucchini, a standard serve is ½ cup, also low in FODMAPs, with large servings >100g, high in fructans.
The important thing to know is that not all green foods have upper limit serving sizes. Most green foods are low FODMAP, even in very large serves. If there is no upper limit noted in the app, then you can safely eat a large amount. This is the case for vegetables such as carrot. Eggplant is green, but when you click on it you will see that very large quantities are amber due to a moderate amount of sorbitol.
The questions that come with this information are around FODMAP stacking. Can I eat ½ cup broccoli, ½ cup zucchini and 1 cup of eggplant all of which are green in these quantities? Are they still green if consumed together in the one sitting? Is there an additive effect?
For the vast majority of IBS patients following a low FODMAP diet, this sort of example will be tolerated. Even if the total FODMAP content goes above the green limit, most people manage to eat amber and even the lower limit of red serves of foods. Should you FODMAP stack during the initial 4 week strict low FODMAP dietary trial? You should feel comfortable eating reasonable portions of green foods in one sitting, but don’t be disheartened if you eat a larger amount. It will not undo all your good work. Most people won’t get symptoms from these type of foods. It’s the really high FODMAP foods that create the most havoc, such as onions, dried legumes and pears.
For foods with upper limit serving sizes, you can modify your meals to ensure your serving size is controlled. Broccoli soup is unlikely to be well tolerated if it is made purely out of broccoli and you eat 2 cups of it. But a modification of the recipe to bulk the broccoli out with parsnip, potato and carrot (all of which are green regardless of how much you eat), the end result will be a low FODMAP broccoli soup. Similarly, if you consider using zucchini strips as a pasta replacement, you just might want to watch how much you use. Keep it to a small zucchini (<100g), add your low FODMAP pasta sauce and serve it with a low FODMAP red cabbage (amber but OK if you don’t eat too much) and parmesan salad – YUM! Recipe coming in the following weeks!
In the end, we want you to remember that a low FODMAP diet should include green and amber foods (and for some people even some red foods). So, you can consume larger servings of foods that may bring them into moderate or high FODMAP levels as long as you don’t experience any nasty symptoms. The diet should be relaxed over time and we hope that the detailed information we share with you through the app will help you to achieve this.
We are more than happy to provide some guidance with further FODMAP stacking questions. What sort of food combinations have you been concerned about? Post them on facebook and we will provide some guidance on whether they are OK, and how you could modify your meal to lower the FODMAP content.