July 6, 2009 - A new study shows that an amino acid known as glutamic acid, which is found in greater amounts in vegetable protein, is associated with lower blood pressure.
This builds on other research linking higher intake of vegetable protein to lower blood pressure.
Researchers say the finding may also help explain in more detail why the DASH (Dietary Approaches to Stop Hypertension) diet works at lowering high blood pressure. The DASH diet is low in sodium and high in vegetables, whole grains, and beans, which are also rich sources of vegetable protein.
Amino acids are the building blocks of protein, and glutamic acid was the most common amino acid found in the study. It accounted for 23% of the protein in people who were mainly vegetable protein eaters, and 18% in who were mainly animal protein eaters.
How Vegetables Help Heart
In the study, researchers analyzed data from 4,680 middle-age people participating in an international population study on the effects of dietary nutrients on high blood pressure. Participants were from the U.S., U.K., China, and Japan.
The results, published in Circulation: Journal of the American Heart Association, showed that a nearly 5% higher intake of glutamic acid as a percent of total protein in the diet was linked to lower average blood pressure. Systolic blood pressure was lower by an average of 1.5 to 3.0 points and diastolic blood pressure was lower by 1.0 to 1.6 points.
Systolic blood pressure is the top number in a blood pressure reading and refers to the force when the heart contracts. Diastolic blood pressure is the lower number in a blood pressure reading and refers to the pressure when the heart is at rest.
Small Reduction, Big Impact
Although the reduction associated with the vegetable protein component was relatively small, researchers say even a small reduction can make a big difference to the health of people with high blood pressure.
“It is estimated that reducing a population’s average systolic blood pressure by 2 [points] could cut stroke death rates by 6 percent and reduce mortality from coronary heart disease by 4 percent,” says researcher Jeremiah Stamler, MD, professor emeritus in the Feinberg School of Medicine at Northwestern University in Chicago, Ill, in a news release.
The American Heart Association estimates that a 6% reduction in 2009 stroke deaths would be equivalent to saving 8,600 people, and a 4% reduction in heart disease deaths would save 17,800 lives per year.
Stamler says these results apply only to dietary sources of glutamic acid and there is no information on the potential effects of glutamic acid dietary supplements.