Whole grains: what’s the big deal?

Nutrition advice almost always starts with “whole grains,” followed by fresh fruits and vegetables. I find this advice to be tiresome. What’s so great about whole grains? Whole grains are the seeds of cereal grasses, such as brown rice, bulgur, whole wheat, and oats. In their natural “whole” state, grains have a hard inedible husk that covers three edible parts: bran (fiber); germ (contains some B vitamins, minerals, fat, and protein); and endosperm (the major portion of the grain, which is mainly starch with a small amount of protein, vitamins and minerals).

Refined grains, such as white flour and white rice, have their bran and germ removed during milling, leaving only the endosperm. Most whole grains are also processed to some degree. For example, whole wheat is ground or crushed to create whole wheat flour; old-fashioned oats are steamed and rolled to make them more palatable and easier to digest.

Often, eye-catching messages on food products include terms such as “Contains 14 grams of whole grains.” Such products often contain high levels of added sugar. In fact, a review of more than 500 grain-based products found that those displaying a “whole grains” stamp contained more sugar than similar products without the stamp. What’s more, whole grains by themselves rank high on the glycemic index, the scale that measures how much a specific food raises blood sugar.

Studies that purport to show an association between whole-grain consumption and good health are examples of “healthy user bias”: those who eat whole grains are people who tend to engage in healthy behaviors such as not smoking, eating lots of fruits and vegetables, and exercising.

Nathan Myhrvold, former Chief Technology Officer for Microsoft, who holds a doctorate in theoretical and mathematical physics from Princeton University and did postdoctoral work with Stephen Hawking, turned his attention to food science. One of his studies compared whole grain bread with white bread. He found no evidence that whole grain bread is better for you than white bread. On a nutrient-by-nutrient basis, whole wheat bread might be slightly better because the bran contains manganese, phosphorus, and selenium, but, he says, “these components are not things that most people run a deficit of.” Plus, our bodies don’t absorb many of the vitamins and minerals in raw grain. Good to know. The only bread in our house is white.

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