As we’ve discussed in previous blog posts, laboratory analysis is the only way to accurately determine the FODMAP content of food products. This is because FODMAP content is influenced by a large number of factors. For instance, in plants, ripeness, plant variety, climate, soil conditions, storage time and storage temperature may all affect FODMAP content. FODMAP levels can even vary within the same plant, depending on the part sampled, for instance the root, stem, bulb, leaves, or whole plant.
Processed foods are particularly susceptible to variations in FODMAP content, as ingredient selection and food processing methods influence FODMAP composition. Soy milk provides an example of the effect of ingredient selection on FODMAP content, with soy milks made from soy protein lower in FODMAPs than soy milks made from soy beans. This is due to high GOS content of soy beans. The FODMAP content of artificially sweetened products may also be strongly influenced by ingredient selection, as polyol sweetening agents such as xylitol, lactitol, isomaltitol or maltitol may have been added. The following table lists ingredients added to processed foods that may result in a high FODMAP product.
Table 1: High FODMAP ingredients to look for on food labels
| Fructose | Lactose | Polyols | Fructans |
|---|---|---|---|
| Dried fruit | Lactose | Sorbitol | Garlic / garlic salt / garlic powder / garlic extract |
| High fructose corn syrup | Mannitol | Onion / onion salt / onion powder / onion extract | |
| Honey | Xylitol | Wheat (if a main ingredient) | |
| Fruit juice | Isomalt | Rye (if a main ingredient) | |
| Fruit juice concentrate | Erythritol | Inulin | |
| Fruit pieces (if a main ingredient) | Fruit juice | Fructan | |
| Crystalline fructose | Fruit juice concentrate | Fructooligosaccharide (FOS) | |
| Agave syrup | Dried fruit | Chicory / chicory root extract / chicory root powder | |
| Fruit sugar |
A number of food processing techniques also affect FODMAP content, such as boiling, straining, canning and fermentation. Boiling, straining and canning can all lower FODMAP content as water soluble FODMAPs (fructans and GOS), are leached into the surrounding liquid. Straining reduces FODMAP content through the removal of leached FODMAPs.
Processes involving fermentation may also affect FODMAP content, as fermenting microorganisms (such as lactobacilli) feed on FODMAPs (such as fructans and GOS), lowering their content. Consequently, longer fermentation times result in greater reductions in fructan and GOS content. These effects are observed in spelt products, whereby spelt products made without fermentation (such as spelt flour, spelt pasta and spelt flakes) are higher in fructans than sourdough spelt breads, made using traditional methods and a long fermentation time.
Researchers in our department are in the process of publishing findings regarding the effect of food processing on FODMAP content. We will share these with you in greater detail in the coming months.
The variable effects of food processing on FODMAP composition highlight the need for a food certification program that clearly and reliably identifies low FODMAP processed foods. The Monash University Low FODMAP Certification Program does just this. All Monash University certified, low FODMAP foods have undergone the most rigorous and accurate FODMAP testing procedures, providing consumers with confidence that they are choosing safe, low FODMAP food products. All Monash University certified, low FODMAP food products are listed in the ‘Guide’ section of the Monash App and some carry the certification stamp on their food packaging. More information about the Monash University Low FODMAP Certification Program can be found here: http://www.med.monash.edu/cecs/gastro/fodmap/certification/
