For a grain that is used in so many gluten free/IBS friendly recipes and products, corn tends to be a topic of contention in terms of FODMAPs. But why? It’s gluten free (unless contaminated with the protein through processing methods), that much we know, but why do some people react to corn and others not, or, even more confusing, why do different types of corn cause issues for an individual when others are well tolerated?
One of the obvious answers is that all of us react differently to different fermentable carbs, which is true – but it goes deeper than that. The problem with corn is simple – corn is not simple at all. People have sensitivities, intolerances and allergies to different aspects of corn, and not all corn is created equal. This article will deal with the fermentable carbohydrates that corn can contain, as corn allergies and intolerances are not within the scope of this blog. If you are concerned that you have an allergy to corn, please see your doctor.
Since the Native Americans domesticated corn thousands of years ago, it has been extensively bred into many varieties, all of which contain different amounts of FODMAPs, as well as different physical characteristics that lend themselves to certain uses in cuisine and industry. Obviously, for the purpose of this article, I will stick to the species of corn that are intended to be eaten.
This needs to be said. Corn is commonly found as a genetically modified (GMO) product. You may choose to consume non-GMO varieties of corn for personal beliefs, however, genetic modification does not affect FODMAP content. Unless a variety of corn is bred to contain large amounts of fructans, or have a higher fructose:glucose ratio than sweet corn (etc), the GMO corn you find at the supermarket will have the same recommended safe serving size as it’s non-GMO counterpart.
Sweet Corn/Corn on the Cob
Variety: sweet corn.
FODMAP rating: safe in 1/2 cob servings.
Sweet corn is the corn we eat prepared as a vegetable – on the cob, or find tinned in the grocery store. It is picked when immature, before the simple sugars have a chance to convert to starches. Delicious with butter, salt and pepper, it unfortunately has a very close fructose:glucose ratio, as well as a large amount of sucrose, so should therefore be limited to half-cob servings, according to Monash University. Of course, if you know you can eat more without reacting you may continue to do so.
Corn Meal, Polenta/Grits and Popcorn
Variety: dent and flint corn.
FODMAP rating: safe in 1 cup servings.
Corn destined to be consumed as a grain is picked and processed once it has matured, which means the water content in the endosperm is greatly reduced and the simple sugars have largely been converted into starch. Starch is not a FODMAP, which means that products made from corn meal, polenta and popcorn kernels (such as corn tortillas, corn bread and mamaliga) are safe in terms of fermentable carbohydrates, as long as no other FODMAP-containing ingredients have been included in the recipe.
Dent corn has a greater water content than flint corn, which has a much harder, less digestible endosperm; this is due to the differing amounts of floury vs vitreous starch (see Figure 3). For this reason, they are turned into corn meal/polenta and popcorn, respectively.
Cornflour/ Corn Starch
Variety: waxy corn.
FODMAP rating: safe.
Waxy corn contains a different type of starch (amylopectin, rather than the amylose found in the previously mentioned corn varieties), and is more effective as a thickener and stabilising agent in foods. This product doesn’t come from the entire corn kernel but is the isolated amylopectin.
Variety: dent corn (amylose starch).
FODMAP rating: safe but use in moderation.
Consisting of approximately 93-96% glucose (in the form of maltose, a disaccharide of two glucose molecules), corn syrup is considered safe in terms of FODMAPs, though it should still be consumed in moderation, as it is a sugar and very high GI. Corn syrup is produced via a multi-step enzymatic process, which breaks the corn starch down into varying products, including maltose. Corn syrup is available in light and dark varieties; the dark corn syrup is mixed with some molasses, which, while it has a slightly elevated fructose:glucose ratio, should be evened out by the extremely concentrated glucose in the corn syrup.
In the USA, corn syrup is synonymous with glucose syrup, as glucose syrup is nearly always made from corn. In other countries, glucose syrup can be made from wheat, rice, potatoes or tapioca.
High Fructose Corn Syrup
Variety: dent corn (amylose starch).
FODMAP rating: high, avoid.
Once corn syrup (which is mostly maltose/glucose) has been produced, the reaction is taken a step further and the corn syrup is processed with the enzyme glucose isomerase, to convert some of the glucose into fructose. This produces HFCS-42. Liquid chromatography is used to further convert glucose into fructose, to create HFCS-90, which can be blended with HFCS-42 to create HFCS-55.
Regardless of your opinion of the health dangers of HFCS, it is NOT low FODMAP. As the varieties (42%, 55% and 90% fructose) are not labelled differently, it’s best to stay clear.
Other names include: isoglucose, glucose-fructose syrup, fructose-glucose syrup, isolated fructose and fructose syrup (the latter two refer to HFCS-90).
Variety: made from the germ of corn kernels.
FODMAP rating: safe.
FODMAPs are a variety of fermentable carbohydrates. Pure corn oil is 100% fat, so contains no carbohydrates, thus no FODMAPs and is safe to use.
So, there you have it. Different varieties of corn (maize) and their derivatives all have different FODMAP ratings; however, as usual, if your tolerances vary from what Monash has suggested is safe, follow your gut.
Disclaimer: I am not a dietitian or a medical doctor; I have just researched this topic myself. If your health professional has advised you to avoid corn, please do so, as it might not be for a FODMAP-related reason.
Title image credit goes to: http://pixabay.com/en/users/margenauer-271373/