5 Ways to Lower the FODMAP Content of Foods: Effect of Food Processing Techniques

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Earlier this year, new research from Monash University highlighted the tremendous effect that some common food processing techniques can have on the FODMAP content of food. These are very useful “tricks” to know when preparing of choosing foods. They allow you to lower the content of some foods that otherwise would be out of a low FODMAP diet (at least during the elimination phase) and increase the variety of your diet.

5 Ways to Lower the FODMAP content of some high-FODMAP foods:

1. Boiling and straining

Some FODMAPs (fructans and galacto-oligosaccharides or GOS) are water soluble and they leach out in the water every time you boil and strain a food. The research showed that boiling dried red lentils and kidney beans decreased the FODMAP content more and more for every 5 minutes of boiling up to 30 minutes. And straining the boiled legumes reduced it even more. The ultimate boiling process is the one used for canning. There is the advantage that, while sitting in the liquid in the can, the beans/lentils leach out more FODMAPs. Tip: choose canned varieties during the elimination phase (chickpeas and lentils are low enough to be rated “green” by the Monash University App). Then, experiment with cooking other dried beans and lentils once you have passed the oligo-saccharide challenge.

2. Pressing and straining

This refers mostly to the making of tofu.  As firm tofu is made by coagulating the soy milk, then pressing and straining the liquid, it is low in FODMAPs. Conversely, silken tofu is made by coagulating the soy milk in the package it is sold in, where all the liquid (and FODMAPs) remain. Tip: buy only firm or extra firm tofu, strain it from the liquid it is floating in, and pat it dry before using.

3. Fermentation

This is where things get tricky: depending on the food, fermentation can either lower or increase the FODMAP content. Where fermentation helps is in the making of bread. If you know a bit about the low FODMAP diet, you know that wheat is not included, as it is high in fructans and GOS. When bread is made using a sourdough culture, however, the microorganisms in the culture feed on them, and lower the overall FODMAP content of the bread. On the other hand, fermenting raw cabbage to make sauerkraut or kimchi increases the content of the polyol mannitol, as this is a by-product of the fermentation. Tip: if you want to enjoy wheat bread while on a low FODMAP diet (and you don’t need to avoid gluten due to celiac disease), you can have small amounts of true sourdough bread. However, avoid sauerkraut and kimchi, unless you have passed the polyols challenge, and enjoy small quantities of regular cabbage.

4. Pickling

For the first time, this research showed that pickling onions, garlic, and beets reduced the FODMAP content by more than 80%, so much to make onions and beets “green”- rated foods. This is due to the fermentation that occurs when vegetables are immersed in brine, or to the lowering of the pH when they are immersed in vinegar. Tip: if you miss these vegetables, buy pickled varieties and check out the Monash University App for appropriate serving sizes.

5. Activating

This mostly pertains to nuts. Activating involves soaking the nuts in water for a minimum of 12 hours, then dehydrating them at low temperatures. The research showed that activated cashews and pistachios, which are the nuts highest in FODMAPs, had significantly lower FODMAP content than their raw counterpart, possibly because the FODMAPs leached out in the water. The decrease in FODMAP content was not sufficient to rate them “green” at a standard serving but a very small serving of cashews was rated green. Tip: buying activated nuts such as almonds, which are low in FODMAP at small serving sizes, may allow you to eat more of them. After you have completed the re-challenge phase, you can experiment and see how much of these nuts (or perhaps even cashews or pistachios) you can eat.

P.S. Thanks to all my readers! My blog recently was selected by Feedspot as one of the Top 50 Low Fodmap Blogs on the web. This is the most comprehensive list of Top 50 Low Fodmap Blogs on the internet.

Antonella Dewell