What Are FODMAPs? Is a Low FODMAP Diet Key to Treating IBS?

FODMAP is an acronym for a collection of food molecules (mostly sugars) that are short-chained carbohydrates, both fermentable and poorly absorbed in the gut. If you haven’t heard the term “FODMAPs” thrown around at work or at the gym, you probably will soon enough.

Essentially, FODMAPs stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. These are specific sugars found in food, such as fructose, lactose, fructans, galactans and polyols.

Because they’re not absorbed completely by the human body, they’re easily fermented by gut bacteria and can cause significant gastrointestinal (GI) problems.

A team at Australia–based Monash University, led by professor Peter Gibson and including Dr. Sue Shepherd and others, developed the low FODMAP diet.

It provided the first evidence that a low FODMAP diet improves IBS symptoms, and more research since has confirmed that limiting FODMAPs in the diet can benefit certain people who have trouble with these short-chained carbs, particularly those who deal with IBS.

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What Are FODMAPs?

As noted above, FODMAPs are a group of short-chain carbohydrates (sugars) that are not properly absorbed in the small intestine. The term FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols.

FODMAPs are:

1. Fermentable: These carbohydrates are fermented by gut bacteria, producing gas as a byproduct.
2. Osmotically active: They draw water into the intestine.
3. Poorly absorbed: FODMAPs are not completely digested or absorbed in the small intestine.

The most common types of FODMAP foods include:

• Oligosaccharides: Fructans found in wheat, spelt, rye, barley, onions, garlic and some fruits and galactans found in legumes like beans, lentils and soybeans.
• Disaccharides: Lactose found in dairy products.
• Monosaccharides: Fructose found in fruits, many vegetables, honey, table sugar and added sugars like high fructose corn syrup.
• Polyols: Sugar alcohols found in some fruits (like apples, pears and plums), as well as artificial sweeteners like sorbitol, xylitol, maltitol and mannitol.

Effects on Health

FODMAPs are not fully digested or absorbed in the small intestine. Instead, they pass through to the large intestine largely intact.

For most people, consuming FODMAPs doesn’t cause any issues. However, for individuals with sensitive digestive systems, especially those with IBS, these foods can lead to unpleasant symptoms.

There are several reasons for this.

For instance, in the small and large intestines, FODMAPs exert an osmotic effect, drawing more water into the bowel. This increased fluid can lead to intestinal distension, causing bloating and discomfort, and diarrhea in some individuals.

When FODMAPs reach the large intestine (colon), they are rapidly fermented by gut bacteria. This fermentation process produces gas as a byproduct.

The combination of increased fluid and gas production causes the intestinal wall to stretch and expand. This distension can result in bloating, abdominal pain or discomfort, and changes in bowel contractions.

It’s important to note that while these processes occur in everyone, the severity of symptoms can vary significantly between individuals.

In people with IBS or other digestive sensitivities, symptoms may be more pronounced due to heightened gut sensitivity. Meanwhile, healthy individuals may experience minimal or no noticeable effects from consuming FODMAPs.

FODMAPs and IBS

IBS is believed to affect up to 10 percent of the world’s population. A low FODMAP diet has been shown to not only take the burden off the digestive system, but also greatly reduce the symptoms of IBS.

This low FODMAPs diet has brought much needed hope to millions of people because IBS is such a common, complicated disease.

Here are some important facts about IBS from an article published in the journal Clinical Epidemiology:

• Younger women are most at risk, and people over 50 are 25 percent less likely to be affected.
• Only 30 percent of people with IBS will consult a physician for treatment, which tells us that there is a huge group of people out there suffering with IBS and no idea how to treat it because these people don’t even know what they’re up against.
• It’s important to realize that these people aren’t steering clear from the doctor because they don’t want help, but because they’re confused. According to the study, undiagnosed IBS patients “do not have significantly different abdominal symptoms to those who do consult, but they do have greater levels of anxiety and lower quality of life.” The symptoms of IBS are hard to diagnose because they’re so similar to common digestive symptoms.
• Also, even though people are not likely to die sooner because of it, “Patients diagnosed with IBS are highly likely to have other functional diseases and have more surgery than the general population,” which could indirectly lead to higher mortality rates and other sickness and/or disease.

Typically, developing symptoms like abdominal pain, bloating, gas and altered bowel habits (ranging from constipation to diarrhea) indicate IBS. However, the primary cause of IBS is unknown, which has added to its mysterious nature.

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For the past several years, gluten has become a common scapegoat for IBS. In fact, eliminating it has been a growing treatment or approach for all bowel and digestive issues, but this approach is not always necessary or appropriate for every IBS sufferer.

One of the first articles to question the gluten theory was published in the journal Current Allergy and Asthma Reports by Australian researchers who made some serious waves with their 2013 study, “Is Gluten a Cause of Gastrointestinal Symptoms in People Without Celiac Disease?”

After repeating a randomized, controlled trial that appeared to suggest gluten made gastrointestinal symptoms worse, the Monash University scientists were unable to confirm that. “Patients with self-perceived NCGS [non-celiac Gluten Sensitivity] have specific gluten sensitivity,” they reported.

That means many people who believe they’re gluten-intolerant may actually be suffering from other GI issues related to FODMAPs, not specifically gluten.

Next thing you know, this study went viral, and FODMAPs were put on the map.

More research is still needed, and the jury is still out, so don’t go throwing away your gluten-free lifestyle just yet. As research continues to shed light on this topic, there’s still good reason to avoid wheat and most grains for certain people.

If going gluten-free hasn’t resolved your issues, though, you may want to look at adopting a low FODMAP diet and see if FODMAPs are the root cause in your case.

Low FODMAP Diet Benefits

The same Australian researchers set out to discover the real cause of GI complaints and appear confident that the culprits are fermentable oligo-, di- and monosaccharides, along with polyols, more commonly known as “FODMAPs.”

The team took 37 patients with non-celiac gluten sensitivity (NCGS) and IBS and conducted a double-blind, crossover trial where they all were given a reduced FODMAPs diet and then randomly assigned each person to one of three groups for two weeks: high-gluten, low-gluten and a control diet without any gluten.

The results were quite astounding:

• GI symptoms consistently and significantly improved during reduced FODMAPs intake for all participants.
• Every person experienced significantly worse symptoms when gluten or whey proteins were reintroduced into the diet.
• Only 8 percent of participants suffered from gluten-specific effects.
• GI issues linked to gluten were not reproduced.

A 2014 study published in the journal Gastroenterology discovered similar results.

Testing to see how the typical Western diet fared against one low in FODMAPs, the researchers took 30 patients with IBS and eight healthy people who acted as the “control group” and randomly separated them into two groups for 21 days: one that ate less than 0.5 grams of FODMAPs per meal and one that ate “regular” food.

The participants rated their daily symptoms on a 0–100 scale. At the end of the three weeks, they reported an average 22.8 score compared to the 44.9 that came with the typical Australian diet — literally cutting their usual bloating, gas and abdominal pain by 50 percent.

Just think what this can mean for people suffering from IBS all over the world.

Allison Siebecker, ND, MSOM, L.Ac, has seen similar results in her practice regarding small intestinal bacterial overgrowth (referred to as SIBO) — a condition defined as “the abnormal growth in the small intestine of bacteria that are normally found only in the colon.”

Intimately connected, SIBO oftentimes causes symptoms very similar to IBS and is involved in the disease processes that cause IBS. In turn, IBS has actually been shown to cause SIBO.

Essentially designed to restrict food sources (primarily carbohydrates) for harmful bacteria, Dr. Siebecker advises that the “established SIBO treatment diets are the Specific Carbohydrate Diet (SCD), the Gut and Psychology Syndrome Diet (Gaps Diet), the Low Fodmap Diet (LFD) or a combination of these diets such as  SIBO Specific Food Guide (SCD + LFD)…”

To get control of their symptoms without the use of drugs or undergoing surgery, Patsy Catsos, MS, RD, recommends that a FODMAP elimination diet be done for two weeks. Then she recommends re-challenging your body with one FODMAP item at a time, until you get to the final diet that includes all the foods that are well-tolerated.

Anyone with IBS or SIBO will be able to nail down the triggers and get the situation undercontrol within a relatively short period of time.

The hope that this provides patients with IBS and SIBO cannot be overemphasized.

Many times, I’ve heard questions about why IBS and digestive issues aren’t alleviated after a person gives up gluten. Often, a low FODMAP diet turns out to be exactly the answer these people are seeking.

Here is more on the benefits of a low FODMAP diet:

1. Reduced symptoms

Research shows this diet helps reduce abdominal pain and discomfort associated with IBS. Many people also experience less bloating when following a low FODMAP diet.

Furthermore, the diet can help alleviate both diarrhea and constipation, and reducing FODMAP intake often leads to decreased gas production.

2. Improved digestive health

Following a low FODMAP diet can help people identify trigger foods that lead to GI issues, particularly when you reintroduce some FODMAPs. Plus, by eliminating high-FODMAP foods, it helps regulate digestion and absorption of the foods you eat.

3. Better overall health

Reducing IBS symptoms can significantly improve the quality of daily life and overall well-being.

In fact, following this diet may positively affect other aspects of health, potentially reducing fatigue, depression and stress while increasing happiness and vitality.

A low FODMAP diet doesn’t have to be complicated either. It can be personalized based on individual tolerances and preferences.

It’s important to note, however, that while the low FODMAP diet can be highly beneficial for many people with IBS and other digestive issues, it should be undertaken under the guidance of a health care professional to ensure proper nutrition and to avoid potential risks associated with long-term restrictive dieting.

High FODMAP Foods

If you’re looking to avoid FODMAPs, here are the high FODMAP foods to avoid:

Vegetables

• Artichoke
• Asparagus
• Beets
• Bitter gourd
• Broccoli
• Brussels sprouts
• Butternut squash
• Cabbage
• Cauliflower
• Fennel
• Garlic
• Green peas
• Leek
• Mushrooms
• Okra
• Onion
• Peas
• Shallots
• Sugar snap peas

Fruits

• Apples
• Apple juice
• Applesauce
• Apricot
• Blackberries
• Blueberries
• Boysenberries
• Cherries
• Dates
• Dried fruit
• Figs
• Grapes
• Mango
• Nectarines
• Peaches
• Pears
• Plums
• Raspberries
• Watermelon

Dairy

• Cow’s milk
• Custard
• Evaporated milk
• Ice cream
• Soft cheeses
• Sour cream
• Soy milk
• Sweetened condensed milk
• Whey
• Yogurt

Protein foods

• Most legumes

Grains

• Amaranth
• Barley
• Biscuits
• Breads
• Breakfast cereals
• Crackers
• Pancakes
• Pasta
• Rye
• Tortillas
• Waffles
• Wheat

Sweeteners

• Agave nectar
• Fructose
• High fructose corn syrup
• Honey
• Isomalt
• Malt extract
• Maltitol
• Mannitol
• Molasses
• Sorbitol
• Xylitol

Nuts and seeds

• Almonds
• Cashews
• Pistachios

Drinks

• Coconut water
• Fortified wines
• Fruit juices
• Kombucha
• Oat milk
• Rum
• Soda
• Soy milk
• Teas, such as chai, chamomile and fennel

Low FODMAP Foods

It’ll take some getting used to, but don’t worry — in no time flat, you’ll be a veritable expert at avoiding poorly absorbed short-chain carbohydrates.

Keep in mind that the point of a low FODMAP diet is to limit products that ferment in your stomach, not to avoid probiotic-rich, fermented foods. This would be a major mistake because fermented veggies and raw dairy are mainstays of the GAPS protocol.

In fact, you don’t have to completely avoid all FODMAPs, since research shows simply limiting the amount you eat can improve digestive symptoms.

If you do struggle with IBS and digesting FODMAP foods, however, it is safe to eat the following foods that are low in these carbs.

Vegetables

• Alfalfa/bean sprouts
• Bamboo shoots
• Bell peppers
• Bok choy
• Carrots
• Celery
• Chives
• Choy sum
• Cucumbers
• Eggplant
• Fresh herbs
• Ginger
• Green beans
• Kale
• Lettuce and salad greens
• Olives
• Parsnips
• Potatoes
• Pumpkin
• Radish
• Spinach
• Squash (winter, butternut)
• Sweet potatoes
• Tomato
• Turnips
• Water chestnuts
• Yams
• Zucchini

Fruits

• Banana (especially unripe ones)
• Berries
• Cantaloupe
• Grapefruit
• Grapes
• Honeydew
• Kiwi
• Kumquat
• Lemon
• Lime
• Mandarin
• Most melons
• Orange
• Passion fruit
• Pineapple
• Rhubarb
• Strawberries
• Tangerine

Dairy alternatives

• Raw hard cheese (cheddar, colby, parmesan, Swiss, etc.)
• Almond, coconut or rice milk

Protein foods

• Eggs
• Grass-fed beef
• Grass-fed lamb
• Wild-caught fish
• Free-range chicken
• Free-range turkey
• Tempeh

Breads, grains and snacks

• Corn
• Gluten-free breads
• Gluten-free oats
• Gluten-free pasta
• GMO-free corn
• GMO-free rice
• Quinoa
• Rice
• Sorghum
• Sourdough spelt
• Tapioca

Nuts and seeds (sprouted or nut butters preferred)

• Macadamia
• Peanut
• Pecans
• Pine nuts
• Pumpkin seeds
• Sesame seeds
• Walnuts

Condiments

• Cooking oils (avocado, coconut, grapeseed)
• Grass-fed butter
• Maple syrup
• Mayonnaise
• Most herbs and spices
• Mustard
• Olives
• Salad dressings (homemade)
• Soy sauce
• Vinegar

Foods to limit

Additionally, some foods are considered to contain a moderate amount of FODMAPs, so it’s recommended to limit serving sizes:

Fruits

• ¼ avocado
• < 3 cherries
• ½ grapefruit (medium)
• ½ pomegranate (small)
• ¼ cup shredded coconut
• < 10 dried banana chips

Vegetables

• ¼ cup artichoke hearts (canned)
• < 3 asparagus spears
• < 4 beet slices
• < ½ cup broccoli
• < ½ cup Brussels sprouts
• < 1/4 cup butternut pumpkin
• < 1 cup cabbage (savoy)
• < 1 celery stick
• < ½ cup green peas
• < 3 okra pods
• < 10 pods snow peas
• < ½ corn cob
• < ½ cup sweet potatoes

Nuts

• Almonds (< 10)
• Hazelnuts (<10)

It’s important to note that this list does not cover all foods that can and can’t be eaten on the low FODMAP diet.

I recommend consulting your dietitian and the Monash University Low FODMAP Diet App if you’re wondering what foods fit the guidelines.

How to Do It

A low-FODMAP diet is a three-step process designed to help identify which specific FODMAPs trigger your digestive symptoms.

Step 1: Elimination phase

• Strict avoidance of high-FODMAP foods: This phase typically lasts two to six weeks.
• Focus on low FODMAP alternatives: Replace high FODMAP foods with low FODMAP options. For example, swap wheat bread for gluten-free bread, or replace regular milk with almond milk.

Step 2: Reintroduction phase

• Gradual reintroduction of FODMAPs: Introduce one type of FODMAP at a time to identify which ones trigger your symptoms.
• Monitor symptoms: Keep a food diary to track your intake and any resulting symptoms.
• Work with a dietitian: A registered dietitian can guide you through this phase and help you personalize your diet.

Step 3: Maintenance phase

• Limit high FODMAP foods: Once you’ve identified your triggers, you can reintroduce some foods in moderation.
• Create a personalized eating plan: Based on your tolerance, develop a meal plan that fits your lifestyle and manages your symptoms.

Before starting a low FODMAP diet, it’s important to consult with your doctor or a registered dietitian to ensure you don’t create nutritional deficiencies or other issues by following a new way of eating.

It’s also important to be patient, as it may take several weeks to see improvements in your symptoms.

A couple other tips include focusing on specific high FODMAP foods to cut rather than eliminating entire food groups and remembering that it’s still important to eat a balanced and varied diet, even when following this protocol.

Remember, a low FODMAP diet is often used to manage IBS symptoms, but it’s not a cure. It’s essential to work with a health care professional to determine the best approach for your specific condition.