A new study by researchers at Beth Israel Deaconess Medical Center in Boston has found that substituting soy nuts for protein in a healthy diet reduces blood pressure and cholesterol in postmenopausal women with high blood pressure.

In the study, Francine K. Welty, M.D., Ph.D., and colleagues assigned 60 healthy post-menopausal women to eat two diets for eight weeks each, one with soy nuts and other with protein.

The first diet so called Therapeutic Lifestyle Changes diet consisted of the following:

30 percent of calories from fat

7 percent from saturated fat

15 percent from protein

55 percent from carbohydrate

1200 milligrams of calcium per day

Two meals of fatty fish per week

Less than 200 milligrams of cholesterol per day

Another diet was the same as the first diet except that 25 grams of protein was replaced with one half cup of unsalted soy nuts.

At the beginning of the study, 12 women had high blood pressure and 48 had normal blood pressure.   Blood pressure was also measured at the end of the study to evaluate the effect of soy nuts on blood pressure.

Soy nut supplementation significantly reduced both systolic and diastolic blood pressure in all 12 hypertensive women and 40 in the 48 women with normal blood pressure, according to the researchers.

Specifically, the diet with soy nuts lowered systolic and diastolic blood pressure on average by 9.9 percent and 6.8 percent respectively in hypertensive women and 5.2 percent and 2.9 percent in women with normal blood pressure, respectively.

Additionally, in women with high blood pressure, the soy diet also lowered low-density lipoprotein ("bad") cholesterol by 11 percent and levels of apoliprotein B by 8 percent. But it did not change cholesterol levels in women with normal blood pressure.

The magnitude of reduction in blood pressure in the study was high enough to significantly reduce the risk of death and cardiovascular problems in a population, according to the researchers who say "A 12-millimeter of mercury decrease in systolic blood pressure for 10 years has been estimated to prevent one death for every 11 patients with stage one hypertension treated."

The researchers conclude "This study was performed in the free-living state; therefore, dietary soy may be a practical, safe and inexpensive modality to reduce blood pressure. If the findings are repeated in a larger group they may have important implications for reducing cardiovascular risk in postmenopausal women on a population basis."

A scientist affiliated with foodconsumer.org comments that the diets may not heart healthy enough as it consists of the amount of fat equivalent to 30 percent of the total calories.   He said it is not clear the benefit resulted from addition of soy nuts in the diet or removal of protein (animal protein) from the diet while it is certain that substitution of soy nuts for protein provides the benefit.  

Early studies have found that too much of animal protein can be a problem to heart health while plant proteins such as those from soy nuts proved much safer than animal protein. Interested readers may refer to a book titled “The China Study” authored by Dr. T. Colin Campbell, a nutrition professor retired from Cornell University.

The foodconsumer.org scientist also suggests that those who have cardiovascular problems may consider a diet with even lower fat.   Dr.  Dean Ornish, one of a few of medical doctors who dare to use a diet program to treat heart disease, uses a low fat diet with no more than 10 percent of the total calories from fat in patients with heart disease.   And he has found that 99 percent of patients improve or reverse their conditions.

Early studies have found that eating soy nuts can help postmenopausal women reduce hot flashes.

The results of the current study were published in the May 28 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.