Does Lettuce (or Salad) Cause Gas? (Data-Based Answer)


By itself, lettuce doesn’t usually cause excessive gas, unless you eat it in a large volume.

It does have a reasonable amount of fiber, but any gas issues usually come from the other foods people eat lettuce with.

To understand why, there are a few things you’ll need to know…

Why Do Vegetables Like Lettuce Cause Gas?

Gas and bloating is not as complicated as most people think.

Some carbohydrates do not break down in the stomach or small intestine, so they are passed to the large intestine. This is where they are fermented by gut bacteria to extract nutrients, which also produces gas.

If this gas is trapped, it causes bloating. Otherwise, it’s mostly released as flatulence.

This fermentation is a healthy process, it’s good to “feed” your good gut bacteria. However, too much gas at once is obviously uncomfortable.

Most carbohydrates that don’t digest well are covered under “fiber,” but there are also a few others that can cause issues.

Fiber in Lettuce

Lettuce is relatively high in fiber.

It has 2.1 grams of fiber per 100 grams, as you can see in the table below.

For reference, a full “bunch” or head weighs about 580 grams.

  Romaine Lettuce
Energy (kcal) 17
Protein (g) 1.23
Total Lipid (g) 0.3
Carbohydrate (g) 3.29
Fiber (g) 2.1
Sugars (g) 1.19

As someone who eats a lot of salads, it’s possible to eat a full head, which would have about 12 grams of fiber.

To put that into context, adults should aim for at least 20 grams of fiber per day, and some people like me easily get over 50 grams.

In other words, while a full head of lettuce has a good amount of fiber, it’s not an extreme amount.

So it might cause some gas by itself, but lettuce shouldn’t cause an uncomfortable amount of gas or bloating.

Detailed Lettuce Carbohydrate Breakdown

I mentioned that there are a few specific carbohydrates (some classified as fiber, some not) that are known to cause excessive gas.

Most of these are considered FODMAPs, which certain people tolerate particularly poorly.

However, lettuce is very low in any of these hard to digest carbohydrates.

I’ve provided a data table below that I pulled from a study that looked specifically for these carbohydrates like sugar alcohols and oligosaccharides.

  Lettuce, green Lettuce, red
Moisture 91 g 91 g
Fructose 0.92 g 0.55 g
Glucose 1.47 g 0.30 g
Sucrose 0.24 g 0.21 g
Mannitol 0.07 g
Xylitol 0.05 g
Total FOS 0.37 g

Note that glucose and sucrose are relatively easy to digest, we’re concerned with the other ones.

Even in people that are sensitive to these sorts of compounds, it usually takes 5-10 grams in a meal to see any significant gas or bloating.

It’s Probably Not the Lettuce

I’m not saying that eating lettuce isn’t leading to any gas at all, but it’s probably not leading to excessive gas unless you’re somehow eating 2 full heads of lettuce at a time.

Instead, you might want to look at other foods you’re eating alongside lettuce.

For example, I’ve done a few similar breakdowns of common foods in salads that are more likely to cause gas that you might be interested in:

Or you might be eating lettuce with beans, which are much more likely to cause gas problems.

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.