The Low-FODMAP Diet and Gluten Sensitivity

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If you have celiac disease, there's no doubt that you need to follow the gluten-free diet. But if you have non-celiac gluten sensitivity (or irritable bowel syndrome, for that matter), there's some medical evidence that another diet may possibly help you: the low-FODMAP diet.

You may be thinking right now: Oh, no — not another special diet to maintain. And yes, the low-FODMAP diet can be somewhat complicated (but potentially no more so than the gluten-free diet). Here's the low-down on the science behind the diet, and how you can actually follow it.

The Science Behind the Low-FODMAP Diet

"FODMAP" stands for "fermentable oligosaccharides, disaccharides, monosaccharides, and polyols." Oligosaccharides, disaccharides, monosaccharides, and polyols are sugars and fibers that are difficult to digest and then pass through the small intestine without being properly broken down.

The "fermentable" part is important because that's what these types of carbs do in your colon while pulling water passing through your small intestine. This combination of water and gas build-up stretches the intestine causing symptom such as constipation, diarrhea, bloating, excessive gas, cramping and abdominal pain.

In the low-FODMAP diet, developed by researchers at Monash University in Australia to treat irritable bowel syndrome, you reduce or eliminate these compounds, thereby (so the theory goes) reducing or eliminating the symptoms that come with consuming them. 

You may be wondering how this relates to the protein gluten, which is found in wheat, barley, and rye. As it turns out, wheat and the other gluten grains are high-FODMAP foods — in addition to the gluten protein, the grains also contain high levels of fructans, a carbohydrate that's a type of fructooligosaccharide.

What Other Foods Do I Need to Limit?

The bad news is, FODMAPs are found in lots of common foods. The good news is, you may not be sensitive to all types of FODMAPs, so you may not need to limit or eliminate all these foods to feel better.

Gluten grains top the list: according to Monash University, those following the low-FODMAP diet should limit or eliminate all wheat-, barley- and rye-based products, substituting gluten-free cereals, pasta, and other foods.

If you're sensitive to FODMAP foods, you also should watch out for wheat starch, which is beginning to crop up in gluten-free-labeled foods (although wheat starch developed for this use is considered gluten-free, it's still a source of fructans).

According to Monash University, fruits that contain high levels of FODMAP compounds include apples, pears, mangos, peaches, apricots, figs, cherries, nectarines, watermelon, and plums. Unripe bananas, blueberries, limes, papaya, mandarins, rhubarb, strawberries, kiwi, and grapes are considered low-FODMAP.

Vegetables with high FODMAP levels include garlic and onions (many experts advise eliminating these completely), snow peas, mushrooms, cauliflower, Brussel sprouts, asparagus, artichokes, leeks, sweet corn and legumes/beans. You can substitute salad foods such as lettuce and tomato, cucumbers, bell peppers, green beans, and zucchini.

As far as dairy goes, the diet's creators advise limiting or eliminating most lactose-containing dairy products such as milk, yogurt, ice cream and soft cheeses (lactose is a FODMAP). Hard cheeses and lactose-free dairy products should be fine.

Is My Problem Really Gluten or FODMAPs?

There are differences between IBS compared to celiac disease and non-gluten sensitivity. IBS primarily affects the large intestine, while celiac disease and non-gluten sensitivity affect the small intestines. In addition, IBS is an irritation while celiac disease is an immune response and not related to ulcers, bleeding, or significant weight loss. Finally, there is no test for IBS so everything else is usually ruled out before IBS is diagnosed. When it comes to FODMAPS, problems are more related to the large intestine rather than the small intestine.

If your physician has diagnosed you with celiac disease or with non-celiac gluten sensitivity, you should continue to avoid all gluten grains. But if your symptoms don't clear up on a very strict, careful gluten-free diet, you might want to consider talking with a gastroenterologist and a registered dietitian nutritionist about trying a low-FODMAP diet. Typical low-FODMAP diets start with total elimination, reintroduction to foods slowly, and then personalizing your low-FODMAP diet. Trying the specific carbohydrate diet may also help.

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