Life Expectancy Hits Record High in United States

Researchers have offered various theories to explain the "Hispanic Paradox," first recognized in the late 1970s.

One is that it does not exist but is only the result of bad data and confusion over who is classified as Hispanic. This explanation has been largely discounted, said Elizabeth Arias, a demographer at the National Center for Health Statistics and an expert on the topic.

Other theories are that Hispanic immigrants tend to return home to die; that immigrants are inherently healthier than people in the countries to which they move; or that something in the habits or lifestyle of Hispanics in the United States is conducive to good health.

"We have found that the paradox applies more to the foreign-born," Arias said. "That leads us to believe something happens in the assimilation process that takes away the advantage."

Family support, traditional diet and relatively low rates of smoking among immigrants probably contribute to the lower mortality rate among Hispanics. But that is not likely to be the full explanation.

"There isn't just one answer. I think it is a combination of factors," she said.

A study published in April found that life expectancy for women was lower at the start of this decade than in the early 1980s. The researchers theorized that this could be the leading edge of the effect of the obesity epidemic. Another study, published in May, found a widening gap in death rates between college graduates and high-school dropouts.

Do the new statistics contradict those findings?

They might, said Ari B. Friedman, a researcher at Harvard University's Initiative for Global Health who helped write the April study. But it is also possible that some segments of the American population are faring differently than the country as a whole.

"It could well be that among certain groups, among certain places, the obesity epidemic is in decline or never existed at all, and in other places it is marching on," he said.