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What Are FODMAPs? When and How to Follow a Low FODMAP Diet

Written by Lauren Panoff, MPH, RD

Reviewed by Anthony Dugarte, MD 

Published on April 7, 2021

Certain carbohydrates called FODMAPs can worsen digestive symptoms for some people. Here’s all you need to know about these carbs and how to know if you need to eliminate them.

What Are FODMAPs? When and How to Follow a Low FODMAP Diet

What you eat influences your digestive health.

Having certain gastrointestinal conditions can also make you more prone to food sensitivities, which is why some people follow a low FODMAP diet.

Understanding where FODMAPs are found, whether avoiding them makes sense, and how to start a low FODMAP diet can be helpful if you’re struggling with digestive concerns.

What Are FODMAPs?

FODMAP is an acronym that stands for certain types of indigestible short-chain carbohydrates. They are categorized as sugars or dietary fibers.

They pass through your digestive system largely intact.

The F in FODMAPs means “fermentable” as they will ferment in the digestive tract rather than being absorbed into the bloodstream like other types of dietary carbohydrates.

The rest of the acronym stands for:

  • Oligosaccharides
  • Disaccharides
  • Monosaccharides, and
  • Polyols

Some of the best known FODMAPs are lactose, fructose, galactans, and fructans.

These are found in various dairy products, grains, fruits and vegetables, legumes, and sweeteners.

Most people don’t experience symptoms after eating FODMAPs.

However, this isn’t the case for everyone, and some people can benefit from identifying problematic FODMAPs in their diet.

Should You Avoid FODMAPs?

Minimizing FODMAPs isn’t necessary or beneficial for everyone.

In fact, a low FODMAP diet isn’t generally recommended without a suspected clinical reason to do so.

With that being said, if you’ve been experiencing digestive issues related to eating, or have been formally diagnosed with a condition like irritable bowel syndrome (IBS), avoiding FODMAPs in your diet may be beneficial.

Because FODMAPs are resistant to digestion, they pass through the intestinal tract and end up in the colon, where many gut bacteria live.

FODMAPs have an osmotic effect in the intestines, meaning they pull water into the digestive tract, which often triggers diarrhea.

Additionally, certain microbes in the colon ferment (eat) FODMAPs for energy.

While other types of fiber produce methane once they are consumed by bacteria, FODMAPs lead to hydrogen gas production in your intestinal tract.

For sensitive people, this can cause mild to severe gastrointestinal symptoms, which often include bloating and cramping.

Low FODMAP Diet and IBS

The most evidence-based reason to follow a low FODMAP diet is in the case of IBS.

While some research suggests that a low FODMAP diet may be helpful for people with irritable bowel diseases like Crohn’s or ulcerative colitis, more research is needed here because results are not consistent for everyone.

It’s estimated that at least 14% of people in the United States have IBS, but it’s often undiagnosed. IBS is a frustrating condition, as no specific cause for it has been identified.

Generally, someone with IBS has undergone a series of diagnostic tests to rule out other digestive-related diseases before being told they have IBS.

Symptoms of IBS can vary substantially between individuals.

Common complaints include increased gas, cramping, bloating, abdominal distention, and varying periods of diarrhea and constipation.

Mental health concerns like stress can be both a trigger and consequence of having IBS. Many people with IBS experience stress that is linked to a higher likelihood of depression and anxiety.

This is one demonstration of the gut-brain axis, or the two-way communication between the gut microbiome and the brain.

We’ve all experienced how significant stress can influence our digestive system.

Many people with IBS are also prone to stress as a result of the frustration, unpredictability, and lack of specific remedy for their symptoms.

Some studies also suggest that certain diet patterns influence the development of IBS, and can amplify symptoms if unmanaged.

The good news is that a low FODMAP diet is beneficial for the majority of people suffering from IBS.

People who find a low FODMAP diet therapeutic for IBS often experience a significant improvement in quality of life.

Of course, this can depend on how strictly one adheres to the process of identifying and removing FODMAPs from their diet.

What Foods Have FODMAPs?

The goal of following a low FODMAP diet isn’t to remove every source of this sugar, as this would be difficult and unsustainable long term.

Rather, the intent of a low FODMAP diet is to identify which foods are triggers and adjust or avoid those.

Some of the most well-known foods that contain FODMAPs and can be triggering include:

  • Sweetening agents: high fructose corn syrup, honey, xylitol, mannitol, sorbitol, fructose
  • Beverages: drinks with high fructose corn syrup (soda, sports drinks), soy milk, fruit juices, beer, fortified wine
  • Fruits: apples, canned fruit, dates, blackberries, cherries, pears, peaches, watermelon, ripe bananas
  • Vegetables: broccoli, Brussels sprouts, garlic, onions, fennel, leeks, mushrooms, shallots, asparagus, artichokes cauliflower, cabbage
  • Dairy products: milk, ice cream, yogurt, cheese, whey protein, and milk powder
  • Grains: wheat, barley, rye
  • Nuts: cashews and pistachios
  • Legumes: beans, peas, lentils, soybeans

This list contains items that make up a large portion of many people’s diets.

It’s not realistic or necessary to exclude every source of FODMAPs forever, but rather to identify which ones are triggers.

This can be achieved via an elimination diet, which we will discuss below.

FODMAP-Friendly Foods

A low FODMAP diet can seem very restrictive. Being aware of the many foods that can still be enjoyed can help make the experience less overwhelming.

Some FODMAP-friendly foods include:

  • Water, coffee, tea
  • Lactose-free dairy products
  • Meat and fish
  • Eggs
  • Nuts and seeds, excluding cashews and pistachios
  • Molasses, stevia, and maple syrup
  • Non-wheat grains like quinoa, sorghum, corn, oats, and rice
  • Low FODMAP vegetables like eggplant, cucumbers, bell peppers, bok choy, carrots, spinach, kale, lettuce, potatoes, zucchini, sweet potatoes, and tomatoes
  • Low FODMAP fruits like strawberries, blueberries, raspberries, unripened bananas, kiwi, and oranges
  • Fats, oils, herbs, and most spices that don’t contain onions or garlic

How to Follow a Low FODMAP Diet

The low FODMAP diet begins as an elimination diet.

The best way to approach it is to first understand which foods in your current diet contain the most FODMAPs.

These foods are removed for at least a few weeks to see if digestive symptoms subside and to settle any existing irritation that may be present from eating them.

The eliminated foods are then individually reintroduced, generally for three days at a time, to see how your digestive system responds.

Sensitivity to all FODMAPs is rare. It’s more common to identify the ones that are most triggering.

Even then, you may be able to tolerate certain amounts of these without needing to totally exclude them.

Following a low FODMAP diet requires attention, especially in the beginning, as you exclude and reintroduce items.

Keep a food journal to record any symptoms and identify patterns.

It’s also helpful to note if you eat something that has no effect and can likely be considered a safe food.

The Bottom Line

When it comes to digestive conditions, it’s important not to self-diagnose.

Starting a restrictive diet, like the FODMAP diet, without a specific diagnosis can lead to unnecessary nutrient deficiencies and food restrictions.

Be sure to speak with your healthcare provider to determine the cause of your symptoms first.

If diagnosed with IBS or another digestive condition that may benefit from low FODMAP, it’s a good idea to work with a dietitian who can help identify trigger foods and provide sustainable nutrition guidance.

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