Onions, artichokes, garlic and leeks all contain fructans – carbs that can cause gas and bloating.

Why does onion make me fart?

Onions contain fructose, which the intestine breaks down during digestion. The breakdown of the sugar causes gas to form. The gas from onions is also likely to cause an odor.

Do onions cause excessive gas?

Onions contain fructans, which are soluble fibers that may cause bloating. Fructans also occur in garlic, leek, agave, wheat, and a range of other gas-producing foods. Even in small quantities, onions and garlic can cause bloating and other digestive issues.