(Scientific American) Last month the American Society for Nutrition (ASN) reaffirmed in a report that fiber-rich whole grains lower the risks of diabetes and heart disease. Media outlets such as Reuters duly reported the news, but many failed to point out a crucial detail: some whole grains may do nothing to reduce disease risks. In fact, many foods legally marketed as whole grains could actually harm health.

The term “whole grain” might evoke an image of a whole, intact grain—that is, a fiber-rich coating of bran surrounding a starchy endosperm and a small reproductive kernel known as the germ. But in a definition created in 1999 by the American Association of Cereal Chemists (AACC) International, an organization of food industry professionals and scientists, and adopted by the U.S. Food and Drug Administration in 2006, “whole grain” refers to any mixture of bran, endosperm and germ in the proportions one would expect to see in an intact grain—yet the grains can be, and usually are, processed so that the three parts are separated and ground before being incorporated into foods.

Note: Read our discussion guidelines before commenting.