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

Published on: 09/25/2018

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 or choosing foods. Indeed, they allow you to lower the content of some foods that otherwise would be excluded on a low FODMAP diet, and increase variety in your diet.

5 Ways to Lower the FODMAP Content of Foods

1. Boiling and straining

One important characteristic of FODMAPs is that they are water-soluble. Consequently, they leach out in the water every time you boil and strain certain foods. The research study showed that boiling dried red lentils and kidney beans decreased the FODMAP content progressively for every 5 minutes of boiling for up to 30 minutes. Straining the boiled legumes reduced it even more.

The ultimate boiling process is the one used for canning. This processing method can further lower the FODMAP content of foods like legumes. The reason why is that, while sitting in the liquid in the can, the beans, chickpeas, or lentils leach out more FODMAPs.

Tip: Choose canned varieties of legumes during the elimination phase (chickpeas, lentils, and a few others are rated “green” by the Monash FODMAP App). Then, once you have passed the GOS challenge, experiment with cooking other dried beans and lentils.

2. Pressing and straining

This refers mostly to the making of tofu. Firm tofu is made by coagulating the soy milk, then pressing and straining the liquid. For this reason, 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. For example, you may know that the low FODMAP diet mostly excludes wheat, as it is high in fructans and GOS. However, when making sourdough bread, the microorganisms in the culture feed on the FODMAPs, 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, you can have small amounts of authentic sourdough bread. However, limit sauerkraut and kimchi to very small portions, unless you have passed the mannitol challenge, and enjoy small quantities of regular cabbage.

4. Pickling

This research showed that pickling onions, garlic, and beets reduced the FODMAP content by more than 80%. This was enough 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 FODMAP 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 (high in FODMAPs) had significantly lower FODMAP content than their raw counterpart. This happened possibly because the FODMAPs leached out in the water. Unfortunately, the reduction in FODMAP content was not sufficient to rate them “green” at a standard serving. However, a very small serving of activated 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 reintroduced FODMAPs, you can experiment and possibly increase the variety and quantity of nuts you can enjoy.

P.S. Thanks to all my readers! Feedspot recently selected my blog 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.

Want to learn more?

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I’m a registered dietitian with a passion for helping women with IBS find their way back to eating without fear of painful gut symptoms and without unnecessary diet restrictions.

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