Everyone knows the rhyme about beans being good for your heart, and most people can identify broccoli, brussels sprouts, cauliflower, and cabbage as gassy foods. Did you know that avocados, garlic, bell peppers, onions, cucumber, artichokes, and asparagus are also gas-producing? Soy is also notoriously hard to digest. Many of these foods contain a complex sugar called raffinose, and/or fructose, both of which can cause gas. And it's not only vegetables; fruit can also give you gas.