What Are FODMAPs and Should You Be Avoiding Them?

What is a Low-FODMAP Diet?

FODMAP is an acronym that stands for fermentable oligo-, di-, monosaccharides, and polyols. These types of carbohydrates are known to trigger digestive symptoms in certain subpopulations [1]. As such, a low-FODMAP diet is commonly prescribed by gastroenterologists when dealing with patients who suffer from irritable bowel syndrome (IBS) or other gastrointestinal complications, such as gut dysbiosis and leaky gut syndrome.

Avoiding high-FODMAP foods means gut bacteria have fewer short-chain carbohydrates to ferment, which may be beneficial for people with IBS and gut dysbiosis. In turn, following a low-FODMAP diet can improve long-term quality of life and health in susceptible individuals.

However, a low-FODMAP diet is not guaranteed to remedy IBS symptoms, and the jury is still out as to whether it's more effective than a traditional IBS diet. Read on to learn about the theoretical health benefits of eliminating foods high in FODMAPs and if it's the right approach for relieving your digestive issues.

What Are the Symptoms of IBS and Gut Dysbiosis?

People with IBS or gut dysbiosis share many of the same digestive symptoms after eating foods that trigger their condition. These symptoms typically include:

  • Bloating
  • Abdominal cramping
  • Episodic constipation or diarrhea
  • Unexpected weight loss
  • Mood disturbances and brain fog
  • Difficulty sleeping
  • General fatigue

A low-FODMAP diet is an elimination diet where certain foods are removed (generally one at a time) to identify culprits that trigger the symptoms above. But why are foods high in FODMAPs a problem for some people and not for others?

Well, irritable bowel syndrome and gut dysbiosis are complex conditions with still relatively misunderstood etiologies [2]. Numerous factors may confound the root cause of digestive symptoms in people with IBS and gut dysbiosis.

The human gut is an intricate interface between the body's intestinal cells and trillions of bacterial cells, some of which are responsible for producing enzymes that adults may not produce (enough of) endogenously, like lactase and cellulase [3]. Thus, lactose and cellulose are common culprits of digestive symptoms in many adults.

As part of the fermentation process, bacteria and other microbes in the gastrointestinal tract produce short-chain fatty acyl compounds like butyrate and propionate, which are then utilized by intestinal cells for energy.

What Happens When You Eat High-FODMAP Foods?

In most cases, FODMAPs are actually a good thing for the gut since the cells in the intestine and colon have specialized enzymes that utilize microbial fermentation end-products for energy and reducing inflammation [4]. Essentially, some high-FODMAP foods are also suitable sources of prebiotic fiber.

However, in people with IBS and gut dysbiosis, methanogens and sulfate reducers in the intestine and colon may produce excessive amounts of methane and hydrogen sulfide gas — known for its pungent rotten-egg odor — when fermenting FODMAPs [5]. Consequently, colon cells prioritize removing excess sulfur from the body over energy production, leading to digestive symptoms.

Furthermore, the colonic environment's pH and osmolality can be altered by FODMAPs, further exacerbating IBS symptoms and causing frequent bowel movements [6]. Even in those who don't suffer from a chronic gastrointestinal condition, eating too many high-FODMAP foods can cause flatulence, bloating, constipation, diarrhea, and abdominal cramps [7].

Yet, switching to a low-FODMAP diet won't necessarily eliminate the real trigger foods if you have irritable bowel syndrome or other gut complications. All you might need is to follow a lactose-free diet or gluten-free diet. Many foods can cause digestive symptoms, not just those high in FODMAPs. For example, food allergens like nuts, dairy, and wheat (gluten) can exacerbate digestive/IBS symptoms regardless of FODMAP intake [8].

As a side note, lactose (milk sugar) is not a FODMAP since microbes in the gut do not ferment it; rather, they produce lactase to break it down into its constituent monosaccharides: galactose and glucose.

What Can You Eat on a Low-FODMAP Diet?

Intuitively, low- carbohydrates foods are, by extension, low-FODMAP foods — for example, red meat, eggs, fish, poultry, coconut, and olive oil. However, a diet low in FODMAPs doesn't mean you have to eat nothing but foods that contain protein and fat, like the carnivore diet.

People with IBS may find that eating low-FODMAP foods reduces the occurrence of bloating, flatulence, abdominal cramps, and frequent bowel movements. Quite simply, a low-FODMAP food contains minimal amounts of fermentable carbohydrates. Here is a list of low-FODMAP foods to give you an idea:

  • Eggplant
  • Kale
  • Green beans
  • Broccoli
  • Carrots
  • Parsnips and turnips
  • Tomatoes
  • Lettuce
  • Bananas
  • Grapes
  • Oranges
  • Strawberries and raspberries
  • Rice products (e.g. rice milk, rice noodles, brown rice)
  • Sourdough-spelt bread and sprouted-grain bread
  • Peanuts and walnuts
  • Seeds (e.g. chia, sesame, and pumpkin)
  • Oats
  • Cheddar cheese, bleu cheese, goat’s cheese, feta, parmesan
  • Cottage cheese

Should You Be Avoiding FODMAPs?

A few clinical trials have found that reducing FODMAP intake improves IBS symptoms by a greater margin than a traditional IBS diet, the latter of which prescribes tactful elimination of food allergens, stimulants, lactose, fructose, and sugar alcohols [9].

Yet, the evidence remains equivocal. In fact, a recent meta-analysis of the available literature concluded that there is insufficient evidence that a gluten-free diet improves IBS symptoms and that there is very poor-quality evidence suggesting that a low-FODMAP diet is effective for alleviating symptoms in IBS patients [10].

Lastly, a common question is if probiotics can help eliminate symptoms like flatulence, bloating, and erratic bowel frequency. Quite a few clinical trials show that the right strains of probiotics reduce IBS symptoms and enhance the digestion of otherwise indigestible sugars, especially lactose [11]. As such, it may be beneficial to take a quality probiotic supplement like TL Gut Health if you're struggling with digestive issues.

probiotics for IBS

But if you currently suffer from digestive/IBS symptoms, it's best to seek the guidance of a doctor that specializes in gastrointestinal health (i.e. a gastroenterologist). A low-FODMAP diet and probiotics may or may not relieve your digestive symptoms. Identifying the underlying cause of your symptoms is the most prudent thing to do before jumping on any specific elimination diet or supplement regimen.

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