For centuries, the grains humans ate came straight from the stalk. That means they had a carbohydrate package rich in fiber, healthy fats, vitamins, minerals, plant enzymes, hormones, and hundreds of other phytochemicals. Even after we learned how to grind grain, we still received all of the goodness that grains pack in their three layers. Whole grains have a tough, fibrous outer layer called bran that protects the inside of the kernel. The interior contains mostly the starchy endosperm. Its job is to provide stored energy for the germ, the seed’s reproductive kernel, which nestles inside the endosperm. The germ is rich in vitamins, minerals, and unsaturated oils.
The invention of industrialized roller mills in the late 19th century changed what we obtained from grains. Milling strips away the bran and germ, making the grain easier to chew, easier to digest, and easier to keep without refrigeration (the healthy oils in the germ can turn rancid, giving the grain an off taste). Processing also pulverizes the endosperm, turning it from a small, solid nugget into millions of minuscule particles.
Refining wheat creates fluffy flour that makes light, airy breads and pastries. But there is a nutritional price to be paid. The process strips away more than half of wheat’s B vitamins, 90 percent of the vitamin E, and virtually the entire fiber. It also makes the starch easily accessible to the body’s starch-digesting enzymes.
Returning to whole grains and other less-processed sources of carbohydrates improves health in a myriad of ways. As researchers have begun to look more closely at carbohydrates and health, they are learning that the quality of the carbohydrates you eat is at least as important as the quantity. Most studies show a connection between eating whole grains and better health.
The bran and fiber in whole grains make it more difficult for digestive enzymes to break down the starches into glucose. Soluble fiber helps lower cholesterol. Insoluble fiber helps move waste through the digestive tract. Fiber may also kindle the body’s natural anticoagulants and so help prevent the formation of small blood clots that can trigger heart attacks or strokes. The collection of antioxidants prevents low-density lipoprotein (LDL) cholesterol from reacting with oxygen. Phytoestrogens (plant estrogens) found in whole grains may protect against some cancers.