Soy milk may reduce hypertension.




Journal of Nutrition

Related Monographs

Consumer Data: Soy Isoflavones Hypertension
Professional Data: Soy Isoflavones Hypertension


Blood pressure is created when the heart beats, propelling blood throughout the body. Blood pressure occurs in two distinct phases, corresponding to the contraction and relaxation of the heart muscle. When the heart contracts, it ejects a certain volume of blood out from its right side into the body's largest artery, the aorta. This initial thrust causes "systolic" blood pressure, which is the upper number of your blood pressure reading. As the heart relaxes, the blood presses against the walls of the arteries as it circulates, causing "diastolic" blood pressure, which is the lower number in your reading.

Blood pressure tends to be lower in women than men, and higher in blacks than whites. It rises with age. Blood pressure generally stays within a fairly narrow range. But it does not stay the same at all times. Blood pressure fluctuates, rising during physical and emotional stress and falling when we are relaxed or asleep.

Most people with chronic high blood pressure have hypertension have "primary" hypertension. Another name for this is "essential" hypertension. The exact cause of primary hypertension remains a mystery, although medical scientists are searching hard for answers. Research studies on hypertension have revealed detailed information about alterations in physiology that may lead to chronically elevated blood pressure. Researchers have zeroed in on the kidneys and their role in maintaining the right amount of sodium in the blood.

A recent study examined the potential anti-hypertensive properties of soy milk. Researchers stated that soy has been shown to reduce blood pressure in rats, but human studies have been inconclusive. In this double-blind randomized study, soy milk and cow's milk were compared for 3 months in 40 men and women. Before beginning this study, isoflavone levels in the urine were recorded. After 3 months, both the diastolic and systolic pressure decreased in the soy group when compared to the cow's milk group. The urinary concentrations of isoflavones were also increased, and this was associated with the decrease in blood pressure. The authors concluded that, "chronic soy milk consumption had modest, but significant hypotensive action in essential hypertensive subjects."1


1. Rivas M, et al. Soy Milk Lowers Blood Pressure in Men and Women with Mild to Moderate Essential Hypertension. J Nutr. Jul 2002;132:1900-1902.