健康英语新闻:U.S. study shows living at high altitude reduces risk of dying from heart disease

WASHINGTON, March 25 (Xinhua) -- Researchers at the University of Colorado (CU) and the Harvard University have found that people living at higher altitudes have a lower chance of dying from ischemic heart disease and tend to live longer than others, according to a study published this week in the Journal of Epidemiology and Community Health.

They spent four years analyzing death certificates from every county in the United States. They examined cause-of-death, socio- economic factors and other issues in their research.

They found that of the top 20 counties with the highest life expectancy, eleven for men and five for women were located in Colorado and Utah. And each county was at a mean elevation of 5, 967 feet above sea level. The men lived between 75.8 and 78.2 years, while women ranged from 80.5 to 82.5 years.

Compared to those living near sea-level, the men lived 1.2 to 3. 6 years longer and women 0.5 to 2.5 years more.

"If living in a lower oxygen environment such as in our Colorado mountains helps reduce the risk of dying from heart disease it could help us develop new clinical treatments for those conditions," said Benjamin Honigman, professor of Emergency Medicine at the CU School of Medicine. "Lower oxygen levels turn on certain genes and we think those genes may change the way heart muscles function. They may also produce new blood vessels that create new highways for blood flow into the heart."

Another explanation, he said, could be that increased solar radiation at altitude helps the body better synthesize vitamin D which has also been shown to have beneficial effects on the heart and some kinds of cancer.

Despite these numbers, the study showed that when socio- economic factors, solar radiation, smoking and pulmonary disease were taken into account, the net effect of altitude on overall life expectancy was negligible.

Still, Honigman said, altitude seems to offer protection against heart disease deaths and may also play a role in cancer development.

Colorado, the highest state in the nation, is also the leanest state, the fittest state, has the fewest deaths from heart disease and a lower incidence of colon and lung cancer compared to others.