[ProCOR] Whole- and Refined-grain Intakes and Hypertension Risk in Women
[The study below found that whole-grain intake was inversely associated with the subsequent risk of hypertension, but found no association between refined-grain intake and the risk of hypertension.]
Title: Whole- and Refined-grain Intakes and the Risk of Hypertension in Women
Author: L Wang, JM Gaziano, et al.
Reference: Am J Clin Nutr 2007; 86: 472-79,
http://www.ajcn.org/cgi/content/abstract/86/2/472
Reviewer: Carlos Mendoza Montano, PhD, ProCor contributing editor, APRECOR, Guatemala, e-mail: projhouse@intelnet.net.gt
Problem addressed: A greater intake of whole grains has been shown to prevent CVD, whereas intake of refined grains had no effect or adverse effects on the risk of CVD. The effects of whole and refined-grain intakes in the development of CVD are attributable, in part, to the induced changes in blood pressure (BP). However, epidemiologic evidence regarding the association of whole- and refined-grain intakes with the risk of developing hypertension remains limited.
Purpose of study:
1. To examine the association between baseline whole- and refined-grain intakesand the development of incident hypertension during 10 years of follow-up.
2. To investigate the potential benefit of replacing refined grains with whole grains when the total grain intake stays constant.
3. To calculate the proportion of whole grains in total grain intake, assessing the association of that proportion with the development of hypertension.
Location of study: United States
Study design: This was a prospective cohort study in 28,926 female US health professionals aged >=45 years (Women's Health Study) who were free of baseline CVD, cancer and hypertension in 1992. Baseline whole- and refined-grain intakes were assessed from semi-quantitative food-frequency questionnaires. The investigators identified 8722 incident cases of hypertension from annual questionnaires during 10 years of follow-up.
Results/Findings: After adjustment for known hypertension risk factors, the relative risks (RRs) (and 95% CIs) of incident hypertension were 1.00 (reference), 0.96 (0.89, 1.03), 0.95 (0.88, 1.02), 0.92 (0.85, 0.99) and 0.89 (0.82, 0.97) across the increasing quintiles of baseline whole-grain intake (P for trend = 0.007). When functional cut offs were used, women who consumed 0.5 to < 1, 1 to <2, 2 to <4, and >=4 whole-grain servings/day had multivariate RRs (95% CIs) of 0.93 (0.87, 1.00), 0.93 (0.87, 0.99), 0.92 (0.85, 0.99) and 0.77 (0.66, 0.89), respectively, compared with those who consumed <0.5 whole-grain servings/day. In contrast, refined-grain intake was not associated with the risk of hypertension. The multivariate RRs of hypertension across the increasing quintiles of refined-grain intake were 1.00, 0.97, 0.94, 0.99 and 0.97 (P for trend = 0.80).
Comments: In this large, prospective, cohort study, whole-grain intake was inversely associated with the subsequent risk of hypertension. The association was modest but dose related and independent of known risk factors for hypertension. In contrast, the study found no association between refined-grain intake and the risk of hypertension. The results of this study are consistent with the results of cross sectional studies in which an inverse association between whole-grain intake and the prevalence of hypertension has been reported. The results of the present investigation are also consistent with the results obtained from the large cohort of US female nurses where intakes of selected whole-grain foods were inversely associated with self-reported systolic and diastolic blood pressure after a four-year follow-up. The authors of this article concluded that their findings support the possible benefits of increasing the amount and proportion of whole grains in the daily diet for the primary prevention of hypertension and its multiple cardiovascular complications.
Additional References:
1. Jacobs DR Jr, Meyer KA, Kushi LH, Folsom AR. Whole-grain intake may reduce the risk of ischemic heart disease death in postmenopausal women: the Iowa Women's Health Study. AmJ Clin Nutr 1998; 68: 248-57.
2. Liu S, Stampfer MJ, Hu FB, et al. Whole-grain consumption and risk of coronary heart disease: results from the Nurses' Health Study. Am J Clin Nutr 1999; 70: 412-19.
Title: Whole- and Refined-grain Intakes and the Risk of Hypertension in Women
Author: L Wang, JM Gaziano, et al.
Reference: Am J Clin Nutr 2007; 86: 472-79,
http://www.ajcn.org/cgi/content/abstract/86/2/472
Reviewer: Carlos Mendoza Montano, PhD, ProCor contributing editor, APRECOR, Guatemala, e-mail: projhouse@intelnet.net.gt
Problem addressed: A greater intake of whole grains has been shown to prevent CVD, whereas intake of refined grains had no effect or adverse effects on the risk of CVD. The effects of whole and refined-grain intakes in the development of CVD are attributable, in part, to the induced changes in blood pressure (BP). However, epidemiologic evidence regarding the association of whole- and refined-grain intakes with the risk of developing hypertension remains limited.
Purpose of study:
1. To examine the association between baseline whole- and refined-grain intakesand the development of incident hypertension during 10 years of follow-up.
2. To investigate the potential benefit of replacing refined grains with whole grains when the total grain intake stays constant.
3. To calculate the proportion of whole grains in total grain intake, assessing the association of that proportion with the development of hypertension.
Location of study: United States
Study design: This was a prospective cohort study in 28,926 female US health professionals aged >=45 years (Women's Health Study) who were free of baseline CVD, cancer and hypertension in 1992. Baseline whole- and refined-grain intakes were assessed from semi-quantitative food-frequency questionnaires. The investigators identified 8722 incident cases of hypertension from annual questionnaires during 10 years of follow-up.
Results/Findings: After adjustment for known hypertension risk factors, the relative risks (RRs) (and 95% CIs) of incident hypertension were 1.00 (reference), 0.96 (0.89, 1.03), 0.95 (0.88, 1.02), 0.92 (0.85, 0.99) and 0.89 (0.82, 0.97) across the increasing quintiles of baseline whole-grain intake (P for trend = 0.007). When functional cut offs were used, women who consumed 0.5 to < 1, 1 to <2, 2 to <4, and >=4 whole-grain servings/day had multivariate RRs (95% CIs) of 0.93 (0.87, 1.00), 0.93 (0.87, 0.99), 0.92 (0.85, 0.99) and 0.77 (0.66, 0.89), respectively, compared with those who consumed <0.5 whole-grain servings/day. In contrast, refined-grain intake was not associated with the risk of hypertension. The multivariate RRs of hypertension across the increasing quintiles of refined-grain intake were 1.00, 0.97, 0.94, 0.99 and 0.97 (P for trend = 0.80).
Comments: In this large, prospective, cohort study, whole-grain intake was inversely associated with the subsequent risk of hypertension. The association was modest but dose related and independent of known risk factors for hypertension. In contrast, the study found no association between refined-grain intake and the risk of hypertension. The results of this study are consistent with the results of cross sectional studies in which an inverse association between whole-grain intake and the prevalence of hypertension has been reported. The results of the present investigation are also consistent with the results obtained from the large cohort of US female nurses where intakes of selected whole-grain foods were inversely associated with self-reported systolic and diastolic blood pressure after a four-year follow-up. The authors of this article concluded that their findings support the possible benefits of increasing the amount and proportion of whole grains in the daily diet for the primary prevention of hypertension and its multiple cardiovascular complications.
Additional References:
1. Jacobs DR Jr, Meyer KA, Kushi LH, Folsom AR. Whole-grain intake may reduce the risk of ischemic heart disease death in postmenopausal women: the Iowa Women's Health Study. AmJ Clin Nutr 1998; 68: 248-57.
2. Liu S, Stampfer MJ, Hu FB, et al. Whole-grain consumption and risk of coronary heart disease: results from the Nurses' Health Study. Am J Clin Nutr 1999; 70: 412-19.
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