A diet rich in whole grains does seem to lower a man’s risk of developing heart disease, with the bran component of grains playing a key role, a large study suggests.
Researchers found that among nearly 43,000 middle-aged and older men, those who ate the most whole grains - such as oatmeal, brown rice and some breakfast cereals - were less likely than men with the lowest consumption to develop coronary heart disease over 14 years.
When the investigators looked at two of the major components of whole grains, bran emerged as the lead player. Men who added the most bran to their diet were 30 percent less likely to develop heart disease than their peers who ate no added bran.
Whole grains have three basic components: the outer layer of bran, the inner germ and the starchy layer known as the endosperm. In highly processed grain products, such as white bread, the bran and germ are removed before milling - which also takes away the fiber, vitamins and other nutrients found in those constituents.
Diets rich in whole grain foods such as cooked oatmeal, whole barley, bulgur, popcorn, and breakfast cereals and breads made from whole grains, have been linked to better weight management and a lower risk of type 2 diabetes and heart disease.
The new findings, published in the American Journal of Clinical Nutrition, come from a long-running study of U.S. male health professionals. The study began in 1986, when the men were between the ages of 40 and 75, and has since periodically collected information on the men’s health, diet and lifestyle.
Senior study author Dr. Eric B. Rimm of the Harvard University School of Public Health said he and his colleagues developed a database that allowed them to estimate how many grams of whole grains, as well as how many grams of bran and germ, the men typically ate each day.
That included the bran and germ found naturally in grains, plus any that was added to processed foods or that the men added to food themselves.
Overall, men with the highest intake of whole grains had an 18 percent lower risk of heart disease compared with those who ate the least. And those who consumed the most grams of added bran had a 30 percent lower risk than those who ate no added bran.
But that does not mean that people need to add bran to their food to get the benefit, or that sprinkling bran on that gooey morning doughnut makes it a health food, according to Rimm.
“Added bran is one way to go about it,” he told Reuters Health. But, he added, eating whole grains, rather than highly processed grain products, will help bulk up the diet with bran.
That, though, means not mistaking refined grain products that list the ingredient “wheat flour” for a whole-grain food. Rimm advised making sure the word “whole” is on that ingredient list. When it comes to bread, he said, choosing one “where you can actually see the grain” is a good move.
As for why bran, and whole grains in general, may ward off heart disease, Rimm said the fiber content probably contributes, but it is likely that the full complement of nutrients - including B vitamins, antioxidants, minerals and various plant chemicals - is involved.
He also pointed out that people looking to boost their whole grain intake have a range of options, including ones that are not hard to swallow, like popcorn and some breakfast cereals.
“Unfortunately,” Rimm said, “many people kind of associated whole grains with eating cardboard. But they should know that they have a lot of choices.”
The research received partial funding from cereal maker Kellogg Company.
SOURCE: American Journal of Clinical Nutrition, December 2004.
Revision date: July 5, 2011
Last revised: by Sebastian Scheller, MD, ScD