Whole-Grain Cereals May Lower Heart Failure Risk for Men

BOSTON, Oct. 23 -- Seven servings of whole-grain breakfast cereals a week led to a 29% reduction in the risk of heart failure for men, researchers here found in a large observational study.
The benefit did not apply to refined cereals, Luc Djoussé, M.D., and J. Michael Gaziano, M.D., of Harvard, reported in the Oct. 22 issue of the Archives of Internal Medicine.
The investigators determined the heart failure benefit of whole-grain cereals on the basis of a semiquantitative food questionnaire that prospectively evaluated 21,376 male participants (mean age 53.7) in the Physicians' Health Study I.
Incident heart failure was determined through annual follow-up questionnaires and validated using Framingham criteria.
During an average follow-up of 19.6 years, 1,018 new cases of heart failure occurred. These included 362 of 6,995 participants who did not eat any cereal, 237 of 4,987 who ate one serving or less a week, 230 of 5,227 who ate two to six servings a week, and 189 of 4,167 who ate seven or more servings a week.
For average weekly cereal consumption of zero servings, the hazard ratio (95% confidence interval) was 1 and this group served as the reference.
For one or fewer servings a week, the HR was, 0.92 (CI, 0.78-1.09). For two to six servings, the HR was 0.79 (CI, 0.67-0.93), and for more than seven servings, the HR was 0.71 (CI, 0.60-0.85), (P<0.001 for trend).
These hazard ratios were calculated after adjustment for age, smoking habits, alcohol consumption, use of multivitamins, physical activity, history of atrial fibrillation, valvular heart disease, and left ventricular hypertrophy.
When the findings were stratified by the type of breakfast cereal, the researchers found an inverse association between whole-grain cereals and heart failure (P<0.001) but not for refined cereals (P=0.70 for trend).
Whole-grain cereals, such as shredded wheat, bran cereal, or oatmeal include the entire kernel, the starchy endosperm, and the nutrient-packed germ. In this study, cereals with at least 25% of whole grain or bran by weight were classified as whole-grain, the researchers said.
Refined grains, as in white rice, white bread, or cornflakes have been processed to remove part of the grain and with it, beneficial nutrients. Usually all that is left after processing is the starchy endosperm.
Whole-grain breakfast cereals and cereal products contain important nutrients, such as vitamins, minerals, fiber, and oil that have been reported to lower cardiovascular risk factors and positively influence glucose and insulin metabolism, Drs. Djoussé and Gaziano said.
In addition, cereals contain phytoestrogens and phenolic acids, which have been shown to have health benefits, they said.
Cereal consumption has also been shown to favorably influence other risk factors for heart failure, including body mass index and weight gain over time in male physicians and female nurses. However, refined grains in these studies were positively associated with weight gain in women although not in men.
There are several biological mechanisms by which whole-grain cereals could offer protection, the investigators said. Nutrients such as potassium contained in whole-grain cereals have been shown to lower blood pressure.
In addition, other constituents of cereals may exert beneficial effects on lipid and homocysteine levels or they may have antioxidant properties.
Phytoestrogens in the cereals may improve lipid levels and insulin sensitivity. Finally, slowing starch digestion and promoting satiety may help control body weight, the investigators said.
Study limitations included the failure to distinguish heart failure with and without preserved left ventricular function. The food frequency questionnaire made it impossible to control for total energy intake and other nutrients in the diet, as well as the possibility of inaccurate reporting of cereal consumption.
In addition, the researchers noted that the participants were highly educated male physicians whose behavior may have differed from that of the general population.
In conclusion, they wrote that the benefits of whole-grain breakfast cereals are likely to be mediated by their effect on risk factors such as hypertension, myocardial infarction, diabetes, and obesity.
Additional studies are warranted to confirm these findings and determine specific nutrients responsible for the cereal's protection, they concluded.
Dr. Gaziano has received investigator-initiated research grants from BASF, DSM Pharmaceuticals, Wyeth Pharmaceuticals, McNeil Consumer Products, and Pliva as well as honoraria from Bayer and Pfizer for speaking engagements. He is a consultant for Bayer, McNeil Consumer Products, Wyeth Pharmaceuticals, Merck, Nutraquest, and GlaxoSmithKline.
The Physicians' Health Study is supported by grants from the National Cancer Institute and National Heart, Lung, and Blood Institute (NHLBI).
Dr. Djoussé is supported by a grant from the NHLBI.Primary source: Archives of Internal MedicineSource reference: Djoussé L, Graziano J "Breakfast Cereals and Risk of Heart Failure in the Physicians' Health Study I" Arch Intern Med 2007; 167: 2080-2085.