Whole grains linked to blood pressure reduction, small study

By staff reporter

- Last updated on GMT

Related tags: Blood pressure, Nutrition, Whole grain

A small study into the effects of soluble and insoluble fibre on
blood pressure indicates that individuals with slightly high
cholesterol levels may benefit from including plenty of whole
grains in their diets.

Whole grains have received considerable attention in the last year, especially in the US where the FDA permits foods containing at least 51 percent whole grains by weight and are low in total fat, saturated fat, and cholesterol to carry a health claim, which links them to a reduced risk of heart disease and certain cancers.

The term whole grain is considered to be more consumer-friendly than the term fibre, which leads some manufacturers to favour it on product packaging since it is likely to strike more of a chord of recognition for its healthy benefits.

High blood pressure is known to increase the risk of coronary heart disease, stroke, and other cardiovascular diseases. Amongst other factors, elevated cholesterol can contributed to high blood pressure since the latter is caused by a narrowing of the arteries or loss of elasticity.

The study, conducted by researchers at the US Department of Agriculture and published in the September issue of the Journal of the American Dietetic Association​, found evidence to suggest that whole grain fibre - be it the in soluble form from whole wheat and brown rice or soluble from barley - could significantly lower blood pressure levels in people with slightly elevated cholesterol.

The 25-strong study group (seven men, eight pre-menopausal women and eight post-menopausal women) followed the American Heart Associations' 'Step 1' controlled diet for two weeks.

This was followed by three five-week periods, where the refined carbohydrates, representing 20 per cent of total energy, were replaced with whole wheat and brown rice, or barley, or a combination of the two.

The researchers measured the participants' blood pressure and weight on a weekly basis.

The subjects' blood pressure was seen to decrease in all phases of the study. Systolic blood pressure went down an average of 2.2 mm Hg with the Step 1 diet, and by 1.4 to 6.7 mm Hg more on the following three whole grain diet phases.

Diastolic blood pressure went down by an average of 2 mm Hg with the Step I diet and 2.9 to 3.7 mm Hg more with the whole-grains.

Although the study group was very small, the researchers also made some interesting observations concerning the effects of the men versus the two groups of women.

The men showed the greatest decline in blood pressure when they were following the combined wheat, rice and barley diet, whereas for the women, taken as a whole group, the greatest effect was seen with the barley phase.

The interventions had less effect on the post-menopausal women than they did on the pre-menopausal women and the men.

Overall, the researchers concluded: "In a healthful diet, increasing whole-grain foods, whether high in soluble or insoluble fiber, can reduce blood pressure and may help to control weight."

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