健康英语新闻:Exercise may diminish negative impact of high-salt diet on hypertension: study

LOS ANGELES, March 23 (Xinhua) -- People who are more physically active are less likely to have high blood pressure associated with a high-sodium diet, a new study suggests.

The study was conducted by researchers at the Tulane University School of Public Health and Tropical Medicine in New Orleans, HealthDay News reported on Wednesday.

study findings were presented at the on-going American Heart Association's meeting on nutrition, physical activity and cardiovascular disease, held in Atlanta, said the report.

To explore a potential association between exercise and the hypertensive role of dietary salt, the researchers focused on roughly 1,900 men and women (average age 38) living in a rural region in northern China. None took blood pressure medication during the study, according to the report.

For one week all of the participants consumed 3,000 mg of sodium a day in their diet; for another week, they were placed on a high-sodium diet -- 18,000 mg per day.

Nine blood pressure readings were taken each week, and questionnaires were completed to assess routine levels of physical activity, ranging from "very active" to "quite sedentary."

When switching from the lower-sodium to a high-sodium diet, those who experienced a 5 percent or greater boost in their systolic blood pressure (the heart contraction measure represented by the top figure of a blood pressure reading) were deemed "high salt-sensitive."

Those reporting the most physical activity had a 38 percent lower risk of being highly salt-sensitive than the least active group. This group was the least likely to see a 5 percent or greater rise in their blood pressure in response to a high-salt diet.

Compared with the most sedentary group, those in the next-to- highest activity group had a 17 percent lower risk of salt- sensitivity, and those in the next-to-lowest activity group had a 10 percent lower risk.

The team concluded that engaging in physical activity has a " significant," independent and progressively healthful impact on the degree to which salt sensitivity relates to blood pressure.

"For those with low physical activity, their blood pressure will increase more if they increase their sodium intake," study co- author Dr. Jiang He, chair of the department of epidemiology at the school, said in remarks published by HeathDay News.

"It's a little bit of a surprise," He added. "But this is the first study to look at this particular association between physical activity and salt sensitivity and blood pressure. But after thinking it over it makes sense, because we already know that physical activity will reduce blood pressure."

High blood pressure, or hypertension, is a leading cause of stroke. Because of salt's association with high blood pressure, the American Heart Association recommends consuming less than 1, 500 mg of sodium per day.