Eating lots of whole grains could ward off high blood pressure, according to a study in the American Journal of Clinical Nutrition.
In the study, men with the highest whole-grain consumption were 19 percent less likely to develop high blood pressure than men who ate the least amount of whole grains.
While refining grains removes their outer coating, whole grains retain their bran and germ, so they are richer in many nutrients, Dr. Alan J. Flint of the Harvard School of Public Health in Boston and his colleagues note in their report.
The most recent U.S. guidelines recommend that people get at least 3 ounces, or 85 grams, of whole grains daily, and that they consume at least half of their grains as whole grains.
There's evidence, the investigators note, that women who eat more whole grains are less likely to develop high blood pressure, also called hypertension, but there is less information on how whole grains might affect men's heart health.
To investigate, Flint and his team looked at data from the Health Professionals Follow-up Study, which has followed 51,529 men since 1986, when the study participants were 40 to 75 years old. They looked at a subset of 31,684 men free of hypertension, cancer, stroke or heart disease at the study's outset. During 18 years of follow-up, 9,227 of them developed hypertension.
The men in the top fifth of whole grain consumption, who averaged about 52 grams daily, were 19 percent less likely than the men in the bottom fifth, who ate an average of about 3 grams of whole grains daily, to develop hypertension during follow-up.
When the researchers looked at separate components of whole grains, only bran showed an independent relationship with hypertension risk, with men who consumed the most at 15 percent lower risk of hypertension than men who ate the least. However, the researchers note, the amount of bran in the men's diet was relatively small compared to their total intake of whole grain and cereal fiber.
The relationship between whole grain intake and hypertension risk remained even after accounting for men's fruit and vegetable intake, use of vitamins, amount of physical activity, and whether or not they were screened for high cholesterol.
This suggests that the association was independent of these markers of a healthy lifestyle behavior pattern. It's possible, the researchers say, that the men who ate more whole grains gained less weight over time.
The current findings, Flint and colleagues conclude, "have implications for future dietary guidelines and for the prevention of hypertension."