Researchers don't point to a single superfood. The finding that keeps repeating is a pattern: vegetables, fruit, whole grains and beans make up the bulk of what you eat, and the other foods play a smaller part.

AICR recommends making whole grains, vegetables, fruits and pulses (beans and lentils) a major part of your normal eating, and reports that following its recommendations more closely is linked to a lower cancer risk. The American Cancer Society says the same: whole fruits, a variety of vegetables (dark green, red and orange), fiber-rich beans and peas, and whole grains. The 17% figure is specifically about whole grains. The other foods in the pattern are recommended as part of a healthy way of eating, but they don't each have their own number here.

Fiber is one reason these foods matter. AICR rates the evidence that foods containing dietary fiber lower the risk of colorectal cancer as probable. That rating is for fiber-containing foods, not fiber supplements.

AICR lists intact whole grains such as brown rice, farro, bulgur, sorghum and quinoa. Bread, cereal and pasta count too, when they are made from whole-grain flour that is minimally processed.

AICR uses three standard servings as a practical example of a higher whole-grain intake. Its example is two slices of whole-grain bread plus one ounce of whole-grain cereal. Serving sizes vary by food, so use the choices below as practical portions rather than weighing every grain you eat. As a general guide, about half a cup of cooked brown rice, quinoa or whole-wheat pasta is a useful serving.