Fiber Stalls High Blood Pressure

Medically Reviewed by Charlotte E. Grayson Mathis, MD
From the WebMD Archives

May 15, 2002 -- Eating a high-fiber diet may not only keep you regular, but it may also keep your blood pressure in check. A new study shows that encouraging Americans to eat more foods high in dietary fiber may be a cost-effective way to prevent and lower the prevalence of high blood pressure on a national scale.

About one in five Americans has high blood pressure, defined as blood pressure above 140/90. Left untreated, hypertension can prematurely age the body's organs and lead to heart attack, stroke, or kidney failure.

Researchers studied information from 9,057 men and women over age 40 who participated in the Third National Health and Nutrition Examination Study (NHANES III) and divided them into three groups according to how much fiber they consumed: high, medium, or low total dietary intake.

The study found that 47% of the people in the low intake group had hypertension compared with 44% of those who were in the high consumption group. Although the authors say the differences between the two groups may not be statistically significant, they are significant in terms of the number of people affected, since high blood pressure affects nearly 50 million Americans.

In addition, the differences between the groups were greater among women and people between the ages of 40-54. Nearly one in three women in the low-fiber group had high blood pressure vs. only about one in five in the high-fiber group.

For both men and women in the study, whole grains, such as oats, whole grain breads, and cereals provided the majority of fiber intake compared with other sources such as fruits and vegetables.

"Grains provide about 36% of normal dietary fiber. Therefore, choosing these grains might be a better solution for people trying to meet the guidelines for fiber [intake], says study author Priscilla Samuel, PhD, of the John Stuart Research Laboratories at Quaker Foods and Beverages.

Samuel presented the findings of the study today at the annual scientific meeting of the American Society of Hypertension in New York City.

Whole grains are included as part of the DASH (Dietary Approaches to Stop Hypertension) diet, which has been found to help reduce blood pressure. The diet emphasizes fruits, vegetables, and low-fat dairy products and recommends a daily intake of more than 25 grams of fiber a day. But Samuel says that based on the results of this study, whole grains aren't emphasized enough.

"On a density basis, grains do provide much more of an amount of fiber compared to fruits and vegetables," says Samuel. "That is one of the reasons why we really do believe that they need to be emphasized more than they are right now to [help people] meet the fiber guidelines and in order to have an effect on high blood pressure."