Foods That Cause Gas: Common Culprits, Broccoli, and Fiber

Your lunch was healthy: lentil soup, a big salad, a side of broccoli. An hour later, your stomach starts to rumble. Sound familiar?

Foods that cause gas are mostly foods your small intestine cannot fully digest. Beans, broccoli, cabbage, onions, wheat, dairy, and sugar alcohols are the usual suspects. Bacteria in your colon ferment what reaches them, and gas is the result (1,2). That is a normal part of digestion. Whether it is also uncomfortable depends on the food, the portion, and your own gut.

This article is part of our complete guide to bloating and gas. Below you will find the common culprits, plus straight answers on broccoli and fiber.

written and reviewed by Anouk Martini (registered dietician)

In short

Passing gas 10 to 18 times a day is considered normal (1).
Common gas-forming foods include beans and lentils, cabbage-family vegetables, onions, wheat, dairy, sugar alcohols, and carbonated drinks (1,2).
Broccoli can cause gas, but Monash University rates a typical 1-cup serving as low FODMAP (3).
Fiber can make you bloated (4), so add it gradually and drink more fluids (1).
You do not need to cut out every gas-forming food. Finding your own triggers works better.

What foods cause gas?

The most common gas-forming foods are beans and lentils, vegetables from the cabbage family, onions and garlic, wheat, dairy products if you have trouble with lactose, sugar alcohols, and carbonated drinks. Most contain carbohydrates that are only partly absorbed in your small intestine. They reach your colon, where bacteria ferment them (1,2).

Beans and lentils

Beans are the classic gas food. They contain raffinose family sugars, which are known to cause flatulence (5). Your reaction depends on the bean. In three feeding studies from 2011, fewer than half of the participants noticed more gas in the first week of eating pinto or baked beans every day, and only 19% did with black-eyed peas (6).

Broccoli, cabbage, and cauliflower

The American College of Gastroenterology (ACG) lists broccoli, cabbage, and cauliflower among the vegetables likely to form gas (1). Broccoli gets its own answer further down.

Onions and garlic

Onions and garlic are rich in fructans, a type of FODMAP. Your small intestine does not absorb fructans, so bacteria in your colon ferment them and make gas (2).

Wheat, oats, corn, and potatoes

The ACG also lists certain starches as gas-formers: wheat, oats, corn, and potatoes. Rice is a good substitute (1). Wheat contains fructans too, which colon bacteria ferment (2).

Dairy

If your body does not make enough of the enzyme lactase, lactose from milk and other dairy products reaches your colon undigested and can form gas (1). Unabsorbed lactose can also draw extra water into your small intestine (2). Read more about lactose.

Some fruits

Apples, pears, and watermelon contain fructose, polyols, or both. These are FODMAPs too. In larger amounts, they can reach your colon and ferment there (2).

Sugar alcohols

Sorbitol, mannitol, and other sugar alcohols (polyols) are common in sugar-free gum, candy, and “diet” products. They are poorly absorbed, so they can ferment in your colon (2). Chewing gum and sucking on hard candy also make you swallow more air (1).

Carbonated drinks

Soda, sparkling water, and beer add air and gas to your digestive tract. Carbonated drinks are also listed among the causes of swallowed air and bloating (1).

Which foods cause flatulence, and how much is normal?

Many of the foods above cause flatulence, and passing gas 10 to 18 times a day is considered normal (1). Main gases are harmless and odorless, and that noticeable smells come from trace gases related to what you eat (1).

Which foods make your gas smell stronger differs from person to person. A food diary for a couple of weeks helps you spot your own pattern.

Does broccoli cause gas?

It can. Broccoli is on the ACG’s list of gas-forming vegetables (1). Still, a typical serving is not a heavy FODMAP load. Monash University rates 1 cup of broccoli as low FODMAP overall, with excess fructose as the main FODMAP, mostly in the stalks (3). A normal portion works for many people. A very large plate, especially of stalks, may be more than your gut likes.

If broccoli bothers you, try this:

Start with a smaller portion and see how you feel.
Go easy on large servings of stalks alone. Monash suggests that people who are sensitive to excess fructose stay under about 2 ounces (65 g) of stalks at a time (3).
Eat slowly and chew well.

Does fiber make you gassy?

It can. Many fibers and similar carbohydrates are fermented by bacteria in your colon, and gas is a by-product (2). How much you notice depends on the amount, the type, and how fast you increase it.

In a controlled feeding trial, people ate three versions of a high-fiber diet (about 30 g of fiber per 2,100 calories) for 6 weeks each. Bloating was more common on the high-fiber diets (24% to 33% of participants) than on their usual diet (18%). The rise on the carbohydrate-rich version was not statistically significant (4).

That is not a reason to skip fiber. The ACG suggests adding it gradually and drinking more fluids as you do (1). For example, add one new high-fiber food every few days instead of changing everything at once.

What can you do about gas from food?

You do not need to cut out every gas-forming food. Many of them are nutritious. Finding the ones that bother you works better, and a few habits can help:

Keep a food and symptom diary for two weeks to spot patterns.
Add gas-forming foods slowly, in small portions.
Eat slowly, chew well, and cut back on gum, hard candy, and fizzy drinks (1).
If wheat, oats, corn, or potatoes bother you, try rice instead (1).
Some people find that draining and rinsing canned beans helps.
Try our intolerance test for an indication of which food components may play a role for you.
If you suspect FODMAPs, work with a dietitian on a structured approach. You can read more in our FODMAP guide.

Gassy even when you eat very little? Read Why Am I So Gassy?

What does a digestive enzyme blend like Fodmix do?

Digestive enzymes are proteins that help break down food. Lactase splits lactose into glucose and galactose in the small intestine. The enzyme alpha-galactosidase splits galactans, such as the raffinose in beans. Enzyme supplements provide specific enzymes that you take with a meal.

Fodmix (Quatrase 10,000) is an enzyme blend developed by our in-house dietitians. It contains Alpha Galactosidase (1200 u), Xylose Isomerase (7500 u), Lactase (10,000 FCC), and Invertase (500 u). Fodmix helps reduce occasional gas, bloating, and discomfort, allowing you to enjoy meals without restrictive diets.*

The capsules are easy to twist open, so you can take the powder separately or mix it with water. Fodmix is suitable for children aged 2 and up, vegan, and free of gluten and soy. It is Low FODMAP Certified™ by Monash University.

*This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

When should you talk to a doctor or dietitian?

Do your symptoms persist, are you losing weight without trying, or are you cutting out more and more foods? Talk to your doctor or a dietitian. You can also ask our dietitians a question.

Not sure where to start with foods that cause gas? Our dietitians are happy to think along with you. You can also use the supplement advisor to see which supplement fits your situation:

Sources

American College of Gastroenterology. Digestive health tips: 10 tips on belching, bloating, and flatulence [Internet]. Bethesda (MD): American College of Gastroenterology. Available from: https://gi.org/topics/digestive-health-tips/
Staudacher HM, Whelan K. The low FODMAP diet: recent advances in understanding its mechanisms and efficacy in IBS. Gut. 2017;66(8):1517-27. doi:10.1136/gutjnl-2017-313750
Monash University. FODMAP content of broccoli and broccolini: an update [Internet]. Melbourne: Monash University FODMAP Blog. Available from: https://monashfodmap.com/blog/newly-tested-and-retested-foods-broccoli-and-broccolini/
Zhang M, Juraschek SP, Appel LJ, Pasricha PJ, Miller ER, Mueller NT. Effects of high-fiber diets and macronutrient substitution on bloating: findings from the OmniHeart trial. Clin Transl Gastroenterol. 2020;11(1):e00122. doi:10.14309/ctg.0000000000000122
Elango D, Rajendran K, Van der Laan L, Sebastiar S, Raigne J, Thaiparambil NA, et al. Raffinose family oligosaccharides: friend or foe for human and plant health? Front Plant Sci. 2022;13:829118. doi:10.3389/fpls.2022.829118
Winham DM, Hutchins AM. Perceptions of flatulence from bean consumption among adults in 3 feeding studies. Nutr J. 2011;10:128. doi:10.1186/1475-2891-10-128