Findings suggest replacing refined grains with whole grains may have significant benefits
CHICAGO - Higher intakes of whole grain foods are associated with a lower risk of ischemic stroke in women, independent of known cardiovascular disease (CVD) risk factors, according to an article in the September 27 issue of The Journal of the American Medical Association (JAMA).
Simin Liu, M.D., ScD, from Brigham and Women's Hospital and Harvard Medical School, Boston and colleagues examined the hypothesis that higher whole grain intake reduces the risk of ischemic stroke in women. The study included 75,521 U.S. women aged 38 to 63 years without previous diagnosis of diabetes mellitus, coronary heart disease, stroke, or other CVD in 1984, who completed detailed food frequency questionnaires in 1984, 1986, 1990, and 1994, and were followed up for 12 years as part of the Nurses' Health Study.
The researchers found that compared with women in the lowest quintile of whole grain intake, women in the highest quintile of whole grain intake (2.7 servings per day) had a 43 percent lower risk of ischemic stroke. Adjustment for smoking modestly attenuated this association. This inverse association remained essentially unchanged with further adjustment for known CVD risk factors, including saturated fat and transfatty acids intake. The inverse relation was also consistently observed among subgroups of women who never smoked, did not drink alcohol, did not exercise regularly, or who did not use postmenopausal hormones.
According to background information in the study, although increased intake of grain products has been recommended to prevent cardiovascular disease, prospective data examining the relation of whole grain intake to risk of ischemic stroke are sparse, especially among women. Stroke remains a leading cause of serious disability and death in women. In the United States, approximately 600,000 cases of stroke accounted for 160,000 deaths in 1997. At all ages, more women than men die of stroke.
According to the authors, many of the approximately 4.4 million stroke survivors have permanent disability, and the cost of stroke-related care amounts to $40 billion each year. Because known risk factors for the development of stroke, including hypercholesterolemia, hypertension, obesity, and diabetes mellitus, can be changed through dietary modification, primary prevention holds much promise.
Concerning the type of grain consumed, the researchers write: "Survey data indicate that most of the grains consumed in the United States are processed and refined, with the average consumption of whole grain products at approximately one-half serving per day. In this cohort of female nurses, whole grains accounted for only one third of the servings of total grains, and median consumption of whole grain foods was one serving per day. Even the women in the top quintile of whole grain intake barely approached the three servings per day that are generally recommended. Given that the inverse relation we observed between whole grain intake and ischemic stroke risk in this cohort of women was continuous, although risk reduction seemed to level off at the fourth quintile (about a 30 to 40 percent lower risk rate of ischemic stroke associated with 1.3 servings per day), replacing refined grains with whole grains by even one serving a day may have significant benefits in reducing the risk of ischemic stroke."
The authors conclude: "These findings support the hypothesis that increasing intake of whole grains may help reduce the incidence of ischemic stroke."
(JAMA. 2000;284: 1534-1540)
Editor's Note: The work reported in this article was supported by grants from the National Institutes of Health.
For more information about the Journal of the American Medical Association or to obtain a copy of the study, please contact Jim Michalski at (312) 464-5785 or E-mail: Jim_Michalski@ama-assn.org.
Posted by the Center for the Advancement of Health http://www.cfah.org. For information about the Center, call Petrina Chong, pchong@cfah.org (202) 387-2829.
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