Does Garlic Cause Gas?: (A Science-Backed Answer)


Some people claim that garlic gives them gas, and there’s actually some research that can help explain it.

Allergies to garlic are quite rare, so it usually comes down to the actual content of garlic.

I’ll break down the reasons why garlic can cause gas for some, and go over what your options of dealing with it are.

Gas 101: What Causes Flatulence?

While most people don’t know much about flatulence, it really isn’t complicated.

Certain carbohydrates do not break down significantly in the small intestine. They are passed to the large intestine where bacteria breaks them down as much as possible so you can digest their nutrients. This fermentation process creates gas as a byproduct, which is then expelled.

There are several carbohydrates that are tough to digest and can go on to cause gas, but the main ones we’ll be looking at are:

  • Oligosaccharides
  • Fructose
  • Fructans
  • Fiber

Carbohydrate Breakdown of Garlic

Here’s the amount of carbohydrates that are found in significant amounts in 100 grams of garlic (source).

Keep in mind that a normal clove of garlic is about 5 grams, so it’s quite rare to eat anywhere close to 100 grams in a serving.

Moisture 63 g
Fructose 0.64 g
Glucose 0.82 g
Sucrose 2.05 g
Fructans 17.4 g
Total FOS 1.2 g
Raffinose .56 g

Even though fructose can cause gas issues (and sucrose is also half fructose), it’s likely not an issue in garlic because it’s a relatively small amount.

Both FOS (fructooligosaccharides) and raffinose are types of oligosaccharides, which are known to cause gas because they cannot be digested in the small intestine. There’s a reasonable amount of them in garlic, and in a large serving of garlic, they could certainly contribute to stomach problems.

But the most likely cause of gas from garlic is the high amount of fructans…

Why Fructans in Garlic Cause Gas

As the name suggests, fructans are related to fructose.

Fructose is a single simple sugar molecule, and fructans are a small polymer chain of fructose.

Even in a small serving of garlic, there’s still a lot of fructan.

It turns out that garlic is one of the highest foods in fructan by a large margin (source).

Just as fructose itself is hard to digest, fructans are even harder to break down, which is why they can cause digestive issues like:

  • Bloating
  • Gas
  • Constipation
  • Diarrhea

Not everyone has the same response to fructans, as the gut microbiome can differ significantly from one person to another.

Does Garlic Have a Lot of Fiber?

Fiber is also a common source of gas, which is why I included the nutritional data below for 100 grams of raw garlic.

However, 2.1 grams per 100 grams of garlic isn’t particularly high, and most people won’t come close to eating a serving that large.

Energy (kcal) 149
Protein (g) 6.36
Total Lipid (g) 0.5
Carbohydrate (g) 33.1
Fiber (g) 2.1
Sugars (g) 1

In other words, while fiber is often a cause of gas in other foods, it’s not likely relevant here.

Why Does Garlic Cause Gas? (Summary)

Some people do find that garlic gives them gas.

Garlic does contain a significant amount of fiber and sugars like fructose and oligosaccharides that often lead to gas.

However, unless you’re eating a full head of garlic, you’re unlikely to eat enough to cause an issue.

The most common reason that garlic causes gas is because it’s very high in fructans, which causes gas and bloating in some people.

If you’d like to test out if you react highly to fructans, you can try eating other foods that are high in fructans like:

  • Jerusalem artichokes (12.2 g of fructan per 100 grams)
  • Shallots (8.9 g)
  • Leek (7.1 g)
  • Spring onion (6.3)

Can You Do Anything About Garlic Giving You Gas?

Unfortunately, there’s not too much you can do to reduce any bloating or flatulence that garlic causes you.

Obviously, you can eat less, as any reaction will be proportional to the amount of garlic consumed.

In addition, make sure your garlic is cooked. You don’t want to overcook it or it will lose its flavor, but I would advise adding raw garlic powder to foods, or large pieces of garlic that have barely been cooked.

About the author

Dale Cudmore

Your friendly neighborhood vegan from Toronto. I've spent over 6 years as a freelance nutrition writer and researcher. During this time, I've tested over 50 vegan protein powders, and over 100 other types of vegan supplements.

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