Natural Foods Merchandiser

Science Briefs

Soy Milk Lowers Blood Pressure
Drinking soy milk helps reduce blood pressure in people with hypertension, according to results of a study conducted by Miguel Rivas, M.D., of the Medical School of Zaragoza in Spain.

Rivas conducted a three-month double-blind study involving 40 people aged 18 to 70 with mild to moderate essential hypertension. Researchers randomly assigned participants to drink 500 ml of either soy milk or nonfat cows' milk twice a day for three months. At the end of the study, the soy milk drinkers lowered their blood pressure significantly compared with the cows' milk drinkers. Their average systolic blood pressure was reduced 18.4 mm Hg, diastolic 15.9 mm Hg and mean blood pressure 16.7 mm Hg.

Rivas found a direct correlation between an individual's urinary output of genistein, a soy isoflavonoid, and blood pressure reduction. Genistein can decrease sodium loss in the urine, which may help account for its effectiveness.

Compared with cows' milk, soy contains more of the amino acid arginine, which is transformed by the body into the blood vessel relaxer nitric oxide. The researchers suggest that a crossover design is the next step in assessing soy's ability to lower blood pressure in hypertensives.

—Journal of Nutrition 2002 Jul;132:1900-2.

High-Carb Drinks Increase Alertness
Soldiers of the future may carry canteens of sugary drinks based on the results of a new U.S. Army study on carbohydrates and alertness. Harris Lieberman of the U.S. Army Research Institute of Environmental Medicine conducted the double-blind placebo-controlled study involving 143 men in the 75th Ranger Regiment, of Fort Lewis, Wash., to see if carbohydrate-rich beverages boost alertness during a physically demanding day.

On test day, the men went on a 12-mile march with backpacks weighing 37.5 pounds (17 kg) and did two three-mile runs without the load. In between, they had two meals, rested and napped. Researchers gave the soldiers canteens with a flavored beverage containing different amounts of the artificial sweetener aspartame and maltodextrin, a sugar. Although the three formulations tasted the same, they contained either 0 percent, 6 percent or 12 percent carbohydrate by volume.

The soldiers wore sophisticated "vigilance monitors," which emitted a random tone. The men responded by pushing a button. At all times, the men with the carbohydrate-rich drink responded more quickly. In addition, the men supplemented with carbohydrates reported much less confusion and more vigor, both during times of exercise and during rest. The researchers concluded that supplementation with carbohydrates "enables individuals to maintain optimal cognitive function when they are engaged in sustained physical activity," both by increasing glucose to the brain and by increasing levels of the neurotransmitter serotonin.

—American Journal of Clinical Nutrition
2002 Jul;76(1):120-7.

Dietary Antioxidants Help Prevent Alzheimer's
A diet rich in antioxidants may help protect against Alzheimer's disease, according to results of the Rotterdam Study involving 5,395 people aged 55 and older.

In 1990, researchers determined the participants' intakes of beta-carotene, flavonoids, vitamin C and vitamin E. During the next 10 years, participants were screened for Alzheimer's disease; a neurologist, neuropsychologist and magnetic brain imaging confirmed the condition in 146 of the subjects. Compared with participants whose diets provided fewer antioxidants, those with greater vitamin C intake cut their Alzheimer's risk nearly 30 percent; those with greater vitamin E intake by up to 43 percent.

Smokers experienced the greatest risk reduction from antioxidants. Smokers, unlike the overall study population, also reduced their Alzheimer's risk when they consumed more beta-carotene and flavonoids.

Maryanne Engelhart, M.D., director of this population-based prospective cohort study, suggests that by decreasing excess oxidation in the brain, antioxidants may prevent the DNA damage, neuron cell death and build-up of the brain-clogging substance beta-amyloid that typify Alzheimer's disease.

—Journal of the American Medical Assoc.
2002 Jun 26;287:3223-9.

Natural Foods Merchandiser volume XXIII/number 9/p. 42

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