Feeling confused about how canned champignon (button) mushrooms can be low FODMAP? That’s not surprising, as button mushrooms are well known for being high FODMAP! The good news is that manufacturing processes, like canning, can have a huge impact on the FODMAP content of food. Both the type of food and the liquid it is stored in can influence the overall FODMAP level of canned foods.
How does canning the food decrease the FODMAP content?
FODMAPs are water-soluble carbohydrates. This means when a high FODMAP food is stored in water or brine the FODMAPs can leach out of the food and into the liquid, lowering the overall FODMAP level (1).. However, it can be hard to predict if enough of the FODMAP content will leach out of the food to reduce the FODMAPs from high to low levels (2). This means to get accurate data on FODMAPs the canned food needs to be tested by a FODMAP trained laboratory.
What high FODMAP foods become safe to eat when canned?
Canned Champignon (Button) Mushrooms in Brine
Fresh button mushrooms are high FODMAP for mannitol in ½ cup servings and contain both high levels of mannitol and moderate levels of fructans in 1 cup servings. Canned champignon mushrooms are popular in Asian cuisine, and they are low FODMAP in ½ cup serves1. This is most likely because the mannitol & fructans in the champignon mushrooms leach into the brine, lowering the overall FODMAP content of the mushrooms themselves. Just remember to buy champignon mushrooms in brine (NOT sauce) and rinse them well before using them.
Boiled lentils contain moderate amounts of FODMAPs (some of the FODMAP content leaches into the water as you boil them), however, canned lentils are much lower in FODMAPs1. This is because the water-soluble GOS (oligosaccharides) and fructans leach out of the lentils into the water content1. Always rinse canned lentils well before using!
Canned Chickpeas (Garbanzo beans)
Dried chickpeas are considered high FODMAP, however, their canned counterparts are much lower in FODMAPs. Again the GOS in the chickpeas leaches out into the water and lowers the chickpea FODMAP level, making a ¼ cup serve of canned chickpeas low FODMAP (1). However, always remember to rinse them before using them.
Canned Baby Corn
Baby corn is an immature ear of corn that is picked before it has a chance to mature. Canned baby corn is low FODMAP in 1 cup serves. However, be careful to avoid canned sweet corn kernels as these are high FODMAP even in small serves (1).
Does canning reduce the FODMAP content of all legumes/beans?
Unfortunately, while canning reduces the FODMAP content of some legumes/ beans, it doesn’t make all of them low FODMAP. Canned baked beans, borlotti beans, four bean mix, butter beans, and black beans are still high FODMAP, although some may have a smaller serving size that only contains low to moderate levels of FODMAPs (1). Check the Monash Low FODMAP App for more information.
What about canned fruit?
Monash University is yet to test a wide range of canned fruit. We do know that canned guava is low FODMAP in 27g serves (1).
If you want to consume canned fruit, then my team of registered dietitians would recommend that you test your tolerance to low FODMAP fruit that is canned in syrup not fruit juice. Fruit juice can contain excess fructose and polyols, which can increase the overall FODMAP level of the product. Instead, buy canned fruit in syrup. Look for ones that contain water and sugar, and avoid any syrups that contain high fructose corn syrup or high FODMAP sweeteners. Then rinse your fruit well using a sieve before consuming, to remove any additional FODMAPs in the liquid.
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Be Aware of Canned Tomato…
Just before you throw two cans of plain crushed tomatoes into your spaghetti bolognese… be aware that canned tomatoes appear to have higher levels of FODMAPs compared to fresh tomatoes. According to the Monash App a ½ cup (92g) serve of canned tomato is low FODMAP, however, contains moderate FODMAPs at a 115g serve, and becomes high FODMAP at a 1 cup (180g) serve (1). This means you need to split a 400g can of tomatoes between four serves. You can make your tomato sauce go further by adding low FODMAP chicken stock, a little bit of tomato paste, and some cornflour (starch) to thicken.
Watch Out For Sneaky FODMAPs
Avoid canned food that has added high FODMAP ingredients like onion, garlic, or high fructose corn syrup, as these will increase the FODMAP content of the food.
Canning high FODMAP foods can reduce their FODMAP content, however, it is hard to predict if enough FODMAPs will leach into the water to make the food low FODMAP. This means you should check the Monash low FODMAP app to see if your canned food is low FODMAP before consuming.