Reference Number: 685
Year: 2010
Link: Link to original paper
Health: Blood pressure
Nutrition: Whole grain
Summary
ABSTRACT
Background: Three daily portions of whole-grain foods could lower cardiovascular disease risk, but a comprehensive intervention trial was needed to confirm this recommendation. Objectives: We aimed to assess the effects of consumption of 3 daily portions of whole-grain foods (provided as only wheat or a mixture of wheat and oats) on markers of cardiovascular disease risk in relatively high-risk individuals. Design: This was a randomized controlled dietary trial in middle aged healthy individuals. After a 4-wk run-in period with a refined diet, we randomly allocated volunteers to a control (refined diet), wheat, or wheat + oats group for 12 wk. The primary outcome was a reduction of cardiovascular disease risk factors by dietary intervention with whole grains, which included lipid and inflammatory marker concentrations, insulin sensitivity, and blood pressure. Results: We recruited a total of 233 volunteers; 24 volunteers withdrew, and 3 volunteers were excluded. Systolic blood pressure and pulse pressure were significantly reduced by 6 and 3 mm Hg, respectively, in the whole-grain foods groups compared with the control group. Systemic markers of cardiovascular disease risk remained unchanged apart from cholesterol concentrations, which decreased slightly but significantly in the refined group. Conclusions: Daily consumption of 3 portions of whole-grain foods can significantly reduce cardiovascular disease risk in middle-aged people mainly through blood pressure–lowering mechanisms. The observed decrease in systolic blood pressure could decrease the incidence of coronary artery disease and stroke by 15% and 25%, respectively. This trial was registered at clinicaltrials.gov as ISRCTN27657880.
Summary of Paper
This study set out to test a simple but important question: Does eating more wholegrain foods actually improve blood pressure and other heart health markers in otherwise healthy, middle?aged adults? Although whole grains are widely recommended, surprisingly few controlled trials had tested their direct effects.
Researchers recruited 233 healthy adults aged 40–65 who were slightly overweight but did not have major illnesses. Everyone began with a 4?week run?in period where they all ate refined grain foods only. This ensured that everyone started the trial from the same baseline.
After this run?in, participants were randomly assigned to one of three groups for 12 weeks:
- Continue eating refined grains (control group)
- Replace some refined grains with whole wheat foods
- Replace some refined grains with a mix of whole wheat and whole oat foods
The wholegrain groups were asked to eat three servings of whole grains per day, which is similar to many public health recommendations.
The most important result was that both wholegrain groups experienced a meaningful reduction in blood pressure, especially systolic blood pressure. On average, systolic blood pressure fell by about 6 mmHg in the wholegrain groups compared with the refined grain group.
A reduction of this size is clinically relevant: population studies suggest that lowering systolic blood pressure by 5 to 6 mmHg could reduce the risk of heart disease and stroke by 15 to 20%.
Other cardiovascular risk markers, such as cholesterol, insulin sensitivity, and inflammatory markers, did not change significantly. This suggests that the main measurable benefit of wholegrain intake in this relatively healthy population was its effect on blood pressure.
Significance to the baker
The study provides causal evidence that replacing refined grains with whole grains can lower blood pressure in healthy adults. Because the participants were not hypertensive and were generally well, the findings imply that whole grains may help prevent high blood pressure from developing in the first place. The authors concluded that eating three servings of whole grains per day is a simple, practical dietary change that can produce a measurable improvement in blood pressure within a few months.