Are mushrooms low FODMAP? Is corn low FODMAP? All your low FODMAP diet questions answered!

What is the low FODMAP diet?

The low FODMAP diet is a gut healing protocol, created at Monash University in Australia, that removes certain fibers found to cause GI distress in some individuals. While the diet does not eliminate all fiber, as perhaps a carnivore-type diet might do, it removes specific types of carbohydrates that have certain qualities that can make them irritate a damaged gut.

These fibers make up the acronym FODMAP: fermentable oligosaccharides, disaccharides, monosaccharides and polyols. Foods that are high in these fibers are taken out during the removal phase, then are gradually added back in during the reintroduction phase. The goal, besides reduction of symptoms, is to eventually add higher FODMAP foods back into the diet, as they should be tolerated by a healthy gut.

Who can benefit from the low FODMAP diet?

In a healthy, robust gut that has a balanced microbiome, these fermentable sugars actually feed beneficial microbes in the gut–-these are prebiotics. However, in a gut that has inflammation and dysbiosis, these compounds can feed the pathogenic, unwanted microbes and lead to worse GI symptoms.

​This diet was created to help those suffering with IBS (irritable bowel syndrome) and functional gut disorders, but others who have gut issues may benefit as well, including those without an IBS diagnosis but have symptoms of dysbiosis in the gut, such as chronic bloating, abdominal pain, constipation and/or diarrhea. 

How long should the low FODMAP diet be followed?

As a practitioner, recommending the low FODMAP diet can be tricky, as it is only to be followed for a short period of time. Generally, the removal or avoidance phase of the diet is followed from 2-6 weeks, depending on the person. While this protocol can provide symptom relief to IBS sufferers and others, it is not to be followed for the long term.

​Because the low FODMAP diet restricts prebiotic fibers that feed gut bacteria, any beneficial microbes present will also be missing their main source of nutrients. If followed for too long, then, the low FODMAP diet can lead to more problems with the gut due to “starving out” the beneficial bacteria we need to cultivate for a healthy gut. In short, low FODMAP is helpful for temporary relief of symptoms and can help facilitate healing the gut, but is not a long-term solution and should not be followed indefinitely.

How do I transition off of the low FODMAP diet?

Once the removal phase is over, higher FODMAP foods are gradually added in, checking for tolerance and changes in GI symptoms as the re-introduction phase progresses. I typically have clients add foods one at a time, focusing on one category of foods at a time, until all foods are added back in. If foods are not tolerated and cause GI distress, they can be left out and re-tested later when more healing has occurred. Food diaries are very helpful for this process.

Some foods, however, may not be tolerated for quite some time and will not be added in for months or more. It is also important to note that foods contain a range of FODMAPs, and are not  “with FODMAPs” or “without FODMAPs.” Some may tolerate foods at different ranges on this spectrum.

There may be some level of FODMAP tolerance in individuals, and, once the elimination phase is over, they find they can tolerate small to moderate amounts of some foods, but that large amounts or regular consumption of some foods may not be appropriate for a long time as well. This may not be a black-and-white issue for some.

For example, someone may find that a few bites of cheese or a splash of milk in coffee is fine, but that a quesadilla or milkshake is a no-go, as it causes a flare-up of symptoms. This varied level of tolerance can be expected, though may not happen with all high FODMAP foods, and can of course be re-tested after more gut repair has happened. 

What are the pros and cons of the low FODMAP diet?

The benefits of following the low FODMAP diet include relief of uncomfortable digestive symptoms, increased awareness of how certain foods trigger or affect your symptoms, and removal of many processed foods that irritate the gut, regardless of FODMAP content. It can bring down inflammation in the gut, which is necessary for healing the gut lining and creating a healthy, balanced gut microbiome for ultimate healing. 

The downsides to following the low FODMAP diet can include increased anxiety and stress around food choices, especially for those who already are unsure of what to eat and which foods cause GI issues. This should not be followed by those with active eating disorders, as it is an elimination diet that restricts many foods, and can trigger restrictive eating patterns in these individuals. Of course, in these cases, speak with a qualified dietitian to discuss options for improving gut health.

The other “cons” are minor but should be considered: going out to eat is much more difficult (if darn near impossible), eating at friends’ or family members’ houses is more complicated, and meal planning in general takes more effort when a large number of common foods are removed.

Lastly, many healthful foods are eliminated as part of the low FODMAP diet, so intake of certain nutrients can decline if not accounted for and reliance on the quick, easy foods on the “allowed” list can make the diet less nutrient-dense if this is not considered. However, with proper planning and consideration, including working with a dietitian while on the diet, the low FODMAP diet can (temporarily) provide a healthy, balanced diet for most. 

How is low FODMAP different from other gut-healing diets?

Many gut-healing protocols exclude certain types of fibers and/or carbohydrate diets, so in this way, low FODMAP is similar to other gut-focused diets. It differs in the exact type of fiber excluded, however.

In the case of SCD (specific carbohydrate diet) and GAPS diets, the main focus is on eliminating starches and sugars to help relieve GI symptoms. SCD was created for those suffering with IBD (Crohn’s and colitis) and celiac disease, while GAPS was inspired greatly by the SCD approach, focused on those with autism, mental illness, allergies, dysbiosis and other health issues (gut and otherwise). 

Low FODMAP differs from GAPS and some other gut-healing approaches in that it only focuses on what foods to avoid or eliminate, while others may also or only focus on adding in certain foods that are missing, such as collagen-rich broths and stocks, fermented foods, healthy fats, herbs, supplements and more.

I must emphasize that low FODMAP on its own is not the answer, and should be combined with the introduction of healing foods, herbs and other approaches to get the most benefit. I often combine the low FODMAP diet with principles from other protocols to help further gut healing. 

Which foods are allowed and not allowed on the low FODMAP diet?

Finally, the do and don’t list for the low FODMAP diet! Below is the enjoy/avoid list–as I prefer to put it–but note that I have added a few foods that are italicized that are technically low FODMAP, but that frequently cause GI distress in those with IBS, and I often encourage to be avoided during the removal phase as well.

Note that some foods’ FODMAP content changes through processing; souring/fermenting decreases the content in the case of sourdough bread, cheese, or tempeh, while other foods like milk or tomatoes are higher in FODMAP when processed (heated/dehydrated) or cooked for longer (bone broth). Ripe fruits will naturally be higher in FODMAPs that unripe counterparts, in the case of bananas and plantains, as unripe versions contain more starch and less sugar (fructose). 

Enjoy

Vegetables: zucchini, squash, kale, collard greens, spinach, tomatoes, bok choi, green beans, sweet and hot peppers, arugula, basil, eggplant, carrots, lettuce, cucumber, celeriac, fennel, ginger, olives, turnip, radish, potato, sweet potato, pumpkin, seaweed; sauerkraut, kim chi, pickled cucumbers and other veggies without other FODMAPs present  (look out for onions and garlic!)

Fruit: grapes, kiwi, orange, pineapple, strawberries, blueberries, unripe banana, coconut, lemon, lime, raspberries, pomegranate, papaya, green plantain, rhubarb, small amounts of avocado (not over-ripe)
​

Grains, Beans and Nuts: oats, corn (limit sweet corn to ½ cob, eating infrequently), soft corn tortillas, cornstarch, rice, buckwheat, sorghum, teff, sourdough or sprouted bread (small amounts can be enjoyed occasionally), tempeh, lentils, millet, polenta, quinoa, peanuts and natural nut butters, macadamia nuts, pumpkin seeds, sunflower seeds, walnuts, almonds, hazelnuts, pecans, flaxseeds, almond/rice/coconut/oat milk (avoid all oat milk despite being low FODMAP, and non-dairy milks with not-allowed additives)

​Meat, Eggs and Dairy: fresh or frozen meat and seafood, eggs, hard (long-aged) cheese, ghee, lactose-free milk or other lactose-free dairy products (raw milk often tolerated on low FODMAP due to presence of lactase enzyme in raw milk); coconut yogurt; meat stock cooked for 2-4 hours
​
Oils, sweeteners, drinks, etc.: maple syrup, stevia, vanilla and almond extract, unrefined cane sugar, dark chocolate; wine, beer, gin, vodka, whiskey, coffee, green or white tea; most herbal teas; olive, avocado, and coconut oil, spices, soy sauce, sea salt, vinegar, condiments like mustard without FODMAPs

Avoid

Vegetables: onion, garlic, artichoke, asparagus, mushrooms, green peas/sweet peas, snap peas, cauliflower, cabbage, broccoli, brussels sprouts, beets, leeks, scallions-especially bulb, shallots, sun-dried tomato



​
Fruit: apples, pears, mango, cherries, grapefruit, persimmon, plums, peaches, ripe banana, ripe plantain, currants, watermelon, nectarine, apricot, dates, blackberries, boysenberries, fruit juice and dried fruit such as raisins

Grains, beans and nuts: wheat, wheat or white flour, rye, barley and commercial breads, cereals, crackers, etc. made with these grains; all dried beans and legumes other than lentils and tempeh–garbanzo, black, pinto, red, kidney, lima, soy, white, navy, cannellini, and other beans (and flours made from them), black-eyed peas, soymilk, tofu; cashews, pistachios




Meat, Eggs and Dairy: pasteurized milk, condensed and evaporated milk, yogurt, ice cream, butter, cream cheese, cottage cheese, soft/uncured cheese, meat seasoned/marinated with garlic or onion; long-cooked  bone broth


​Oils, sweeteners, drinks, etc.: honey, agave, molasses, all artificial sweeteners, high fructose corn syrup, and sugar alcohols; rum, oolong, chamomile, fennel and chai teas, kombucha; soybean, canola, and vegetable oils, margarine; milk chocolate; garlic and onion powder; inulin, chicory and FOS​

What are fiber sources on the low FODMAP diet?

Though certain fermentable fibers are avoided on low FODMAP, you can still get adequate fiber in the diet during the removal phase if well-planned. Most fiber will be from non-fermentable, insoluble fiber sources–see all the great veggies, fruits, grains and nuts on the enjoy list–as well as starches, including resistant starch in unripe bananas, rice, and potatoes.

​If fiber intake is a concern while on low FODMAP, such as if certain types of fibers need to be introduced to support the gut, there are supplements often tolerated by those with IBS and similar conditions, including psyllium husk, ground flaxseed, and partially hydrolyzed guar gum. Resistant starch “supplements” such as potato starch and green banana flour may also be used if well tolerated, and act as a prebiotic for the colon rather than the small intestine. ​

What about pre-made foods? Can I go out to eat while on the low FODMAP diet?

When buying pre-made, packaged foods while on the low FODMAP diet, reading labels is extremely important. Foods like pasta sauces, ketchup, and salad dressings nearly always contain high FODMAP ingredients like garlic and onion–they’re in everything!--so you are better off making homemade versions of your favorite condiments and other foods or scour the labels for an “allowed” version. However, there are some low FODMAP options out there if you are a diligent label-reader, including those from Fody, a company making specifically low FODMAP foods such as pasta sauce--this is an option if time or cooking skills are limited!

The same goes for going out to eat: restaurant food tends to contain high FODMAP ingredients, so be sure to call ahead of time to where you plan to eat or be specific with the waitstaff about ingredients in your meal. You may find some places that can accommodate your needs but, honestly, cooking at home for the most part will be the best strategy while on this diet--luckily, it is a short-term protocol, so you should be able to enjoy restaurant food again once you are finished and have healed your gut. 

Is the low FODMAP diet all I need to do for gut healing?

Absolutely not! The low FODMAP diet is not a cure-all for the gut. While it is meant to relieve symptoms like gas and bloating, it is not the only strategy used in a proper gut-healing protocol.

​In the case of IBS, dysbiosis such as SIBO is very commonly present, so addressing the overgrowth of pathogenic microbes (bacteria, yeast, and parasites) is essential. Also necessary are looking at what is missing in the diet, hormone balance, gut motility, and lifestyle factors like stress and sleep that affect gut health significantly as well.

​Using low FODMAP as a tool is useful, but is just one piece of the gut-healing puzzle. ​

Want to learn more about healing your gut?

If you want to dig deeper into healing your gut, check out my FREE webinar, Stop Making These 5 SIBO Mistakes!

​You can register for the webinar on my website, laurapoerd.com, which will also sign you up for my email list so you stay up-to-date on my upcoming classes, recent blog posts, and more!