Raw cruciferous vegetables

Greens like broccoli, Brussels sprouts, bok choy, and collard greens are packed with nutrients like vitamin C, folate, fiber, and also contain compounds that could help ward off cancer. Unfortunately, they're not always easy on the tummy. "These veggies contain anindigestible complex sugar called raffinose that is responsible for producing gas," says Cavuto."On top of that, their soluble fiber doesn't break down until reaching the small intestine which may lead to bloating and an upset stomach." 

This doesn't mean that cruciferous fare should disappear from your plate forever. Steaming is an easy hack that not only breaks down the raffinose to make vegetables easier to digest, it also helps preserve the cancer-kicking compounds, which can be lost when boiling or in the microwave.