Lentils
Johanek says the average American needs 25 to 38 grams of fiber a day—but only gets 10 to 16. That gap is worrisome—research suggests that failing to hit the daily recommend numbers boosts colon cancer risk. Johanek recommends lentils as a way to increase fiber and get the digestive system moving. Try throwing some in a soup or salad to up your daily fiber intake.