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The Beginner’s Guide to the Low FODMAP Diet

Written by
Yumna Farooq
Team Nutrisense
Reviewed by
Natalie Carroll
MS, RDN, CDN, CLC
a plate of veggies

With more people taking charge of their own health, wellness and niche diets have become increasingly popular over the last few years, especially influenced by the increasing emergence of chronic conditions, biohacking, and the field of functional medicine.

While we don’t recommend diets as a blanket strategy for all, some diets can promote eating habits that may be beneficial for specific conditions. From the AIP (autoimmune paleo protocol) to the ketogenic diet, the list seems to be ever-growing.

One of these diets is the low FODMAP diet, which has been both anecdotally and scientifically shown to be helpful for gastrointestinal conditions and abdominal pain.

In this article, we break down what the low FODMAP diet entails, why it was created in the first place, and the potential benefits and drawbacks to the low FODMAP diet. 

What is the Low FODMAP Diet?

a cutting board filled with veggies

So what exactly is the low FODMAP diet? To answer this question, we’ll first have to spell out what FODMAP stands for:

  • F: Fermentable 
  • O: Oligosaccharides
  • D: Disaccharides
  • M: Monosaccharides
  • A: And
  • P: Polyols (short-chain, or small, carbohydrates)

Now, putting it all together: the low FODMAP diet is a diet that contains little to no fermentable oligosaccharides, disaccharides, monosaccharides, and polyps (all of which are types of carbohydrates).

In our fiber deep dive, we’ve discussed that fermentable fibers (such as oligosaccharides) can be beneficial for boosting gut health. Oligosaccharides can be found in foods such as onion, asparagus, Jerusalem artichokes, and chicory root.

This type of fiber has a prebiotic effect, with substrates that act as food to the bacteria in your gut. So, consuming these foods can help increase the amount of beneficial bacteria in the microflora helping to correct gut dysbiosis.

However, while fermentable oligosaccharides, disaccharides, monosaccharides, and polyps can be healthy, they can also aggravate functional gastrointestinal (GI) conditions such as irritable bowel syndrome (or IBS) and create symptoms such as bloating and/or abdominal discomfort. 

The History of the Low FODMAP Diet

This diet was first introduced in 2001 as a form of treatment for individuals with GI conditions such as:

  • IBS
  • Small intestinal bacterial overgrowth (or SIBO)
  • Small intestinal fungal overgrowth (SIFO)
  • And, in some cases, gut dysbiosis (an imbalance of the gut flora)

As an elimination diet, the FODMAP diet seeks to alleviate gastrointestinal symptoms from people who were struggling these conditions, such as:

  • Constipation and/or diarrhea
  • Abdominal pain or discomfort
  • Cramping
  • Bloating
  • A change in energy levels and mood
  • Overall reduced quality of life

How FODMAPs Trigger GI Symptoms

Researchers originally hypothesized that high FODMAP foods could lead to GI conditions due to certain food intolerances, which activate a different part of the immune system than allergies (the innate branch).

However, newer studies suggest that FODMAPs worsen GI symptoms in three different ways:

  1. Triggering food hypersensitivity by mast cell pathways (involved in the immune system).
  2. Action of bioactive molecules.
  3. Intestinal lumen distention or increased air or liquid in the intestines, which may lead to bloating distention, and even diarrhea.

This means that when you eat certain foods that have one or more fermentable oligosaccharides, disaccharides, monosaccharides, and/or polyps, which are already more difficult for the body to digest, your gut microbes may have extra trouble breaking down these carbohydrate types. 

Combining these different foods in different ratios can also affect how they are digested. For example, fructose is best digested when it’s consumed in a one to one ratio with glucose. But when there’s more fructose than glucose, the digestion of fructose can be negatively impacted.

Another great example is sorbitol, the most common polyols in our diets. If a person with IBS eats this polyols with fructose, regardless of the ratio, they may experience a worsening of their symptoms.

The Benefits of the Low FODMAP Diet

a plate of salad

We’ve already touched upon how the low FODMAP diet can help GI conditions and symptoms, but let‘s dig into that a little further.

Although this diet is relatively new, there is still a decent amount of research to back up the benefits of the low FODMAP diet, especially in IBS, which include:

The first randomized clinical trial to investigate the effects of eliminating all FODMAPs from the diet was done in 2010, and found that a low FODMAP diet resulted in better carbohydrate digestion.

Another 2010 study found that a low FODMAP diet improved symptoms such as gas, bloating, lethargy in individuals with IBS. Other research has also found that the low FODMAP diet can also help in certain clinical populations such as patients who are experiencing diarrhea related to enteral nutrition (or tube feeding).

A group of researchers from Monash University found that enteral nutrition supplements are three to seven times higher in FODMAP content. So, using low FODMAP enteral supplementation can help with GI symptoms in these cases as well.

The Drawbacks to the Low FODMAP Diet

someone holding a bunch of lettuce

It may appear that the low FODMAP diet has a host of benefits, so are there any cons to this diet? 

First, it’s important to note that the low FODMAP diet isn’t for everyone. Different foods create different reactions in different people, and this diet can primarily be beneficial for people who have trouble breaking this carbohydrate group down.

However, because the symptoms are similar to what other food intolerances or sensitivities can cause, it can be difficult to pinpoint whether it’s FODMAPs specifically or other food groups that‘s creating the symptoms as opposed to lifestyle factors like stress. Wheat is a FODMAP, for example, but it also contains gluten, which very well could be the root cause of someone’s GI symptoms.

You’ll want to work with a medical professional alongside a dietitian or nutritionist to determine whether FODMAPs are your unique cause of GI issues.

The FODMAP and Prebiotic Paradox

Prebiotics fall into the oligosaccharide category of FODMAP. So, what happens when you stop consuming FODMAP-related prebiotics?

One specific type of probiotic (or helpful gut bacteria) that prebiotics encourage the growth of is called bifidobacterium. Bifidobacterium can limit the growth of pathogens and helps regulate the immune system. It also reduces abdominal pain in both healthy people and people with IBS.

Restricting certain FODMAP carbohydrates like oligosaccharides has been shown to reduce the amount of bifidobacterium present in the gut, with one study even showing that people with IBS who have higher levels of Bifidobacterium had the greatest reduction in this probiotic on a low FODMAP diet.

Curiously, the diet that was created to improve GI conditions like IBS actually lowers the amount of bifidobacterium, which can improve IBS symptoms. This may be overcome by looking into direct probiotic supplementation or other low FODMAP foods that can help boost beneficial bacterial growth. Again, you‘ll want to work with your functional medicine doctor or nutritionist to see what’s best for you.

Low FODMAP Diet Guidelines

The concept behind this diet is similar to elimination diets, where a group of foods that worsen symptoms for certain conditions or hinder you from reaching your health goals is removed from your diet. Sometimes foods may be reintroduced later on to see if certain portions and frequency of eating these foods is tolerated.

As with any diet, there are foods you can consume on the low FODMAP diet and foods that are not included in this diet (known as high FODMAP foods). Although your practitioner will give you a timeline that works best for you, these foods are typically eliminated for between two to six weeks.

a plate of fried eggs, garlic and lime

Low FODMAP Foods

Here are some other low FODMAP foods you want to focus on and include in your meals.

a chart of low fodmap foods

Fruits and vegetables:

  • Blueberries
  • Grapes
  • Kiwi fruit
  • Orange
  • Pineapple
  • Raspberries
  • Strawberries
  • Green beans
  • Broccoli
  • Cucumber
  • Kale
  • Lettuce
  • Bell pepper
  • Potato
  • Tomato
  • Zucchini

Protein Sources:

  • Feta cheese
  • Lactose-free milk and yogurt
  • Soy milk 
  • Eggs
  • Firm tofu
  • Plain meats
  • Poultry
  • Seafood and fish
  • Tempeh

Grains:

  • Corn or quinoa flake
  • Oats
  • Quinoa or corn pasta
  • Rice or plain rice products
  • Sourdough spelt bread
  • Wheat, rye or barley-free breads (these will be gluten-free as well)

Nuts and Seeds:

  • Almonds (limit to 10)
  • Macadamia nuts
  • Peanuts
  • Pumpkin seeds
  • Sunflower seeds
  • Walnuts

Sugars:

  • Dark chocolate
  • Maple syrup
  • Rice malt syrup
  • Table sugar

High FODMAP Foods

an artichoke

Now that you know which foods can be eaten on a low FODMAP diet, here are some more high FODMAP foods you may want to eliminate.

a chart of high fodmap foods

Fruits and vegetables:

  • Apples and apple juice
  • Cherries
  • Mango
  • Nectarines
  • Peaches
  • Pears
  • Watermelon
  • Artichoke
  • Asparagus
  • Cauliflower
  • Garlic
  • Green peas
  • Mushrooms
  • Onion

Protein Sources:

  • Cow’s milk
  • Custard
  • Ice cream
  • Sweetened condensed milk
  • Yogurt
  • Most legumes or pulses
  • Some marinated/processed meats, poultry, seafood and fish (ask your dietitian when in doubt)

Grains:

  • Wheat, rye, barley based foods
  • Breads
  • Breakfast cereals
  • Biscuits (cookies and crackers)
  • Snack products

Nuts and Seeds:

  • Cashews
  • Pistachios

Sugars:

  • High fructose corn syrup
  • Honey

How to Start the Low FODMAP Diet

someone slicing radishes and cucumbers

This long list of foods can seem daunting, which is why it’s important to take it slow and consult a dietitian or nutritionist for assistance.

First, you’ll want to determine your unique needs and diet timeline with a medical professional so you know that this diet is right for your symptoms. Your dietitian or doctor can also help guide you with which foods may be more important to eliminate depending on your current diet and which high FODMAP foods you consume most.

Second, you’ll want to start planning and prepping to make the change. Here are some tips to do that:

  • Determine what high FODMAP foods you eat most frequently or love to eat. Find an alternative to those to easily swap them out.
  • Download the FODMAP app to help you easily identify your foods on the go.
  • Make a list of grocery stores or restaurants that have an abundance of low FODMAP foods (so you know where to shop and eat).
  • Create a dedicated cabinet for your low FODMAP foods.
  • Stock up on low FODMAP snacks and food products from brands like FODY and BelliWelli.
  • Meal prep in advance using FODMAP recipes so you’re not caught off guard when you get hungry. Remember, setting yourself up for success is crucial here.
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