Digestive issues are incredibly common.

Not surprisingly, the stuff we put in our bellies can have a major effect on what goes on in there.

This brings us to the topic at hand, FODMAPs.

These are tiny carbohydrates found in certain foods, including wheat and beans.

Studies show strong links between FODMAPs and digestive symptoms like gas, bloating, stomach pain, diarrhea and constipation.

Low-FODMAP diets can provide remarkable benefits for people with common digestive disorders.

FODMAP stands for "Fermentable Oligo-, Di-, Mono-saccharides and Polyols" (1).

In human terms, these are short-chain carbohydrates that some people can not digest.

Instead, they reach the far end of the intestine where the gut bacteria reside.

The gut bacteria then use these carbohydrates for fuel, producing hydrogen gas and causing all sorts of digestive symptoms.

FODMAPs also draw liquid into the intestine, which can cause diarrhea.

Although not everyone is sensitive to FODMAPs, this is very common among people with irritable bowel syndrome, or IBS (2).

About 14% of people in the US have IBS, most of which are undiagnosed, so the implications of this are massive (3).

Common FODMAPs include:

  • Fructose: A simple sugar found in many fruits, vegetables and added sugars.
  • Lactose: A carbohydrate found in dairy products like milk.
  • Fructans: Found in many foods, including gluten grains like wheat, spelt, rye and barley.
  • Galactans: Found in large amounts in legumes.
  • Polyols: Sugar alcohols like xylitol, sorbitol, maltitol and mannitol. They are found in some fruits and vegetables, and often used as sweeteners.
Bottom Line: FODMAP stands for "Fermentable Oligo, Di, Mono-saccharides and Polyols." These are small carbohydrates that many people can not digest.

Starch, the most common carbohydrate in the diet, consists of very long chains of glucose molecules.

FODMAPs, however, are usually "short-chain" carbohydrates.

This means that they are only 1, 2 or a few sugars linked together.

For some people, these carbohydrates pass through most of the intestine unchanged.

When they reach the far end, they get used as fuel (fermented) by the gut bacteria that reside there.

This is usually not a bad thing, and is actually how dietary fibers feed the friendly gut bacteria, leading to all sorts of benefits.

However, the friendly bacteria tend to produce methane, whereas the bacteria that feed on FODMAPs produce hydrogen, another type of gas (4).

When they produce hydrogen, this can lead to flatulence (gas), bloating, stomach cramps, pain and constipation.

Many of these symptoms are caused by distention of the gut, which can also make your belly look bigger (5).

FODMAPs are also "osmotically active," meaning that they can draw water into the intestine and contribute to diarrhea.

Bottom Line: In some individuals, FODMAPs are poorly digested, so they end up reaching the far end of the intestine. They draw water into the intestine and get fermented by hydrogen-producing gut bacteria.

The low-FODMAP diet has mostly been studied in patients with irritable bowel syndrome (IBS).

This is a common digestive disorder that includes symptoms like gas, bloating, stomach cramps, diarrhea and constipation.

IBS has no well defined cause, but it is well known that what people eat can have a significant effect (6, 7). Stress can also be a major contributor (8).

According to some research, about 75% of IBS patients can benefit from a low-FODMAP diet (9, 10).

In many cases, they experience major reductions in symptoms and impressive improvement in quality of life (11).

A low-FODMAP diet may also be beneficial for other functional gastrointestinal disorders (FGID), a term that encompasses all sorts of digestive problems (1).

There is also some evidence that it can be useful for people with inflammatory bowel diseases (IBD) like Crohn's disease and ulcerative colitis (12).

As you may now realize, FODMAPs are implicated in pretty much all of the most common digestive symptoms and disturbances.

If you are intolerant, then the benefits of a low-FODMAP diet may include (9, 10):

  1. Less gas.
  2. Less bloating.
  3. Less diarrhea.
  4. Less constipation.
  5. Less stomach pain.

The diet may also cause various psychological benefits, because these digestive disturbances are known to cause stress and are strongly linked to mental disorders like anxiety and depression (13).

Bottom Line: The low-FODMAP diet can lead to improvements in the majority of patients with irritable bowel syndrome. It also reduces symptoms in various other digestive disorders.

Here is a list of some common foods and ingredients that are high in FODMAPs (1, 14):

  • Fruits: Apples, applesauce, apricots, blackberries, boysenberries, cherries, canned fruit, dates, figs, pears, peaches, watermelon.
  • Sweeteners: Fructose, honey, high fructose corn syrup, xylitol, mannitol, maltitol, sorbitol.
  • Dairy products: Milk (from cows, goats and sheep), ice cream, most yogurts, sour cream, soft and fresh cheeses (cottage, ricotta, etc) and whey protein supplements.
  • Vegetables: Artichokes, asparagus, broccoli, beetroot, Brussels sprouts, cabbage, cauliflower, garlic, fennel, leaks, mushrooms, okra, onions, peas, shallots.
  • Legumes: Beans, chickpeas, lentils, red kidney beans, baked beans, soybeans.
  • Wheat: bread, pasta, most breakfast cereals, tortillas, waffles, pancakes, crackers, biscuits.
  • Other grains: Barley and rye.
  • Beverages: Beer, fortified wines, soft drinks with high fructose corn syrup, milk, soy milk, fruit juices.

Keep in mind that the purpose is not to completely eliminate FODMAPs, because that is extremely difficult.

Simply minimizing them is considered sufficient to reduce digestive symptoms.

These foods are okay to eat on a low-FODMAP diet (1, 14):

  • All meats, fish and eggs, except if if they have added high-FODMAP ingredients like wheat or high fructose corn syrup.
  • All fats and oils.
  • Most herbs and spices.
  • Nuts and seeds: Almonds, cashews, peanuts, macadamia nuts, pine nuts, sesame seeds (not pistachios, which are high in FODMAPs).
  • Fruits: Bananas, blueberries, cantelope, grapefruit, grapes, kiwi, lemons, lime, mandarins, melons, (except watermelon), oranges, passionfruit, raspberries, strawberries.
  • Sweeteners: Maple syrup, molasses, stevia and most artificial sweeteners.
  • Dairy products: Lactose-free dairy products and hard cheeses (including brie and camembert).
  • Vegetables: Alfalfa, bell peppers, bok choy, carrots, celery, cucumbers, eggplant, ginger, green beans, kale, lettuce, chives, olives, parsnhips, potatoes, radishes, spinach, spring onion (only green), squash, sweet potatoes, tomatoes, turnips, yams, water chestnuts, zucchini.
  • Grains: Corn, oats, rice, quinoa, sorgum, tapioca.
  • Beverages: Water, coffee, tea, etc.

As you can see, there is a wide variety of healthy and nutritious foods that you can eat on a low-FODMAP diet.

However, these lists are NOT definitive and there may be other foods that are either high or low in FODMAPs that are not listed.

If you're wondering about a specific food, try looking for "[food name] fodmaps" on Google, such as "garlic fodmaps" (without the quotes).

Many commonly consumed foods are high in FODMAPs.

It is generally recommended to completely eliminate all high-FODMAP foods for a period of a few weeks.

This diet does not work if you only eliminate some high-FODMAP foods, but not others. You need to avoid all of them.

If FODMAPs are the cause of your problems, then you may experience relief in as little as a few days.

After a few weeks, you can add some of these foods back, only one at a time. Then you can figure out which one of them was causing your symptoms.

If you find that a certain type of food really wreaks havoc on your digestion, then you may want to permanently avoid that food.

This can be pretty complicated to do on your own, and it is recommended to seek the advice of a doctor or dietitian who is trained in the application of a low-FODMAP diet.

This can also help prevent unnecessary dietary restrictions, because certain tests can help determine whether you also need to avoid fructose and/or lactose.

Bottom Line: It is recommended to eliminate all high-FODMAP foods for a period of a few weeks, then reintroduce some of them, one at a time. It is best to do this with the help of a qualified health professional.

It's important to keep in mind that FODMAPs aren't "bad."

Many of the foods that contain FODMAPs are considered very healthy.

People who aren't FODMAP intolerant should NOT go on a low-FODMAP diet. That is absolutely pointless, and may even be detrimental.

For some people, FODMAPs are a clean source of energy, or may function like other prebiotic fibers, helping to support the friendly bacteria in the gut.

However, in people who truly have FODMAP intolerance, they feed the wrong type of bacteria and help them cause all sorts of symptoms.

If you have digestive issues that are causing problems in your life, FODMAPs should be on your list of top suspects.

Although a low-FODMAP diet may not eliminate all digestive problems, the chances are very high that it can lead to significant benefit.