Soy protein supplements linked to lower blood pressure.
Participants who took a soy protein supplement had a 2.0 mm Hg lower systolic blood pressure when compared to the refined carbohydrate supplement.
Systolic blood pressure (the top number in a blood pressure reading) gauges the pressure when the heart contracts. Refined carbohydrate supplements were not linked to a change in systolic blood pressure. The 352 adults in the study were at increased risk of high blood pressure or had, mild cases of the condition.
Almost 75 million Americas have hypertension, a "silent killer" that can cause heart attacks, heart failure, strokes, kidney damage, and other potentially fatal events.
"Some previous observational research on eating carbohydrates inconsistently suggested that a high-carbohydrate diet might help reduce blood pressure," said Dr. He. "In contrast, our clinical trial directly compares soy protein on blood pressure and shows that it lowers blood pressure better than carbohydrates."
Participants were 22 years of age or older, with systolic blood pressures ranging from 120 to 159 mm. Hg. and diastolic blood pressures ranging from 80 to 95 mm. Hg. Each participant was randomly assigned to take 40 grams of soy protein or refined carbohydrate supplement every day for eight weeks each. The supplements were formulated in a way that allowed researchers to compare the effects of soy protein and refined complex carbohydrate on blood pressure without changing sodium, potassium, or calcium. Each eight-week phase was followed by a three-week washout period when study participants did not take supplements. The three identical powder supplements were dissolved in liquid.
Blood pressure readings were taken three times at each of the two clinical visits before and two clinical visits after each eight-week phase, yielding a net blood pressure change for each supplement period. The study results showed no decrease in diastolic blood pressure.
"The systolic blood pressure differences we found are small for the individual, but they are important at the population level," Dr. He said.
Based on previous research, a decrease of 2 mm Hg in systolic blood pressure could lead to 6 percent fewer stroke-related deaths, a 4 percent lower rate of deaths from heart disease, and a 3 percent reduction in overall deaths among Americans. Long-term studies would be needed to make specific recommendations for dietary changes, Dr. He said.
In summary, the soy supplements lowered systolic blood pressure more than refined carbohydrate supplements. The researchers suggested that replacing dietary refined carbohydrates with foods or drinks high in soy protein might help prevent or treat high blood pressure.
(Source: Circulation: Journal of the American Heart Association; July 2011.)
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|Publication:||Nutrition Health Review|
|Date:||Mar 22, 2011|
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