Why Do Mushrooms Cause Gas? (3 Reasons)


Mushrooms do cause gas for some people.

Even though they are low in fiber, mushrooms do have a considerable amount of carbohydrates that are hard to digest and can lead to gas production.

I’ll explain why flatulence is caused in the simplest way I can, and then we’ll look at mushroom nutrition data to see why they might cause gas.

Why Mushrooms Cause Gas and Bloating in Some People

Flatulence and bloating are 2 sides of the same coin. When excessive gas is stored in the gut, it causes bloating, and flatulence is how most of it is released.

Where does this gas come from?

Some carbohydrates can’t be broken down, or only partially, in the stomach or small intestine.

When these are passed to the large intestine, where most of your gut bacteria live, they start fermenting these carbohydrates, which produces gas.

That’s all there is to it. A lot of modern research has focused on identifying the specific carbohydrates that don’t digest easily and cause stomach issues.

Carbohydrate Breakdown of Mushrooms

One study measured the amount of several of these hard to digest carbohydrates in mushrooms.

The ones that were detected are shown in the table below for 2 types of mushrooms, which is for a 100 gram serving of raw mushrooms.

Aside from sucrose, all of these are tough to digest and can cause significant gas when consumed in large amounts.

Mushroom, button Mushroom, oyster
Moisture 92 g 92 g
Fructose 0.27 g 0.24 g
Sucrose 0.42 g 0.34 g
Sorbitol 0.21 g 0.11 g
Mannitol 1.33 g 0.41 g
Xylitol 0.16 g
Total FOS 0.28 g 0.15 g

Even though the raw quantity of fructose is comparable to the other ones in the table, it’s a relatively low amount of fructose compared to many other fruits and vegetables, so it’s not likely to cause issues.

The bigger concerns are the sorbitol, mannitol, and total FOS (fructooligosaccharides).

Sorbitol and mannitol are both sugar alcohols that are hard to digest and can cause gas and bloating in people sensitive to them if they consume just a few grams. A single serving of 100 grams of mushrooms likely isn’t enough to cause serious stomach issues, but eating a larger quantity could.

Also, as you can see just from this data of 2 types of mushrooms, the amounts can vary significantly. It’s possible that only certain types of mushrooms will cause you an increased amount of discomfort.

Can the Fiber in Mushrooms Cause Gas?

The hardest carbohydrate to digest is one that you probably already know – fiber.

Fiber is an umbrella term for carbohydrates that can’t be digested by the small intestine at all.

So let’s look at the amount of fiber and other nutrients in a 100 gram serving of mushrooms (raw).

Energy (kcal) 22
Protein (g) 3.09
Total Lipid (g) 0.34
Carbohydrate (g) 3.26
Fiber (g) 1
Sugars (g) 1.98

Mushrooms are very low in calories, and yet have a decent amount of protein (mushrooms are comparable to meat in terms of protein per calorie).

The main thing we can see is that mushrooms are quite low in fiber, it is very unlikely that this amount would cause anyone significant gas, even in a large serving.

How to Test if Mushrooms Are Giving You Gas?

If you get gas after eating a meal with mushrooms, it might be something else in the meal causing you issues.

If you can’t stomach the idea of eating mushrooms by themselves to test them, you can also try eating other foods that are high in sorbitol and mannitol to see if you’re highly sensitive to them.

Other foods high in sorbitol include:

  • Blackberries
  • Blueberries
  • Nectarines
  • Pears
  • Avocado

And other foods high in mannitol include:

  • Cauliflower
  • Celery
  • Peas

Try eating a few hundred grams of any of these foods alone and see if you develop any significant gas a few hours after. If so, then it’s likely that mushrooms will also cause you gas.

About the author

Dale Cudmore

Your friendly neighborhood vegan from Toronto. Chemical engineer turned semi-professional soccer player and freelance nutrition writer. I've been vegan for years and try to make life easier for others by sharing what I've learned.