Back in the 1990s, the federal government tried an unusual social experiment: It offered thousands of poor women in big-city public housing a chance to live in more affluent neighborhoods.
A decade later, the women who relocated had lower rates of diabetes and extreme obesity _ differences that are being hailed as compelling evidence that where you live can determine your health.
The experiment was initially aimed at researching whether moving impoverished families to more prosperous areas could improve employment or schooling. But according to a study released Wednesday, the most interesting effect may have been on the women's physical condition.
About 16 percent of the women who moved had diabetes, compared with about 20 percent of women who stayed in public housing. And about 14 percent of those who left the projects were extremely obese, compared with nearly 18 percent of the other women.
The small-but-significant differences offered some of the strongest support yet for the idea that where you live can significantly affect your overall health, especially if your home is in a low-income area with few safe places to exercise, limited food options and meager medical services.
"This study proves that concentrated poverty is not only bad policy, it's bad for your health," Shaun Donovan, secretary of the Department of Housing and Urban Development.
But no one believes the deficit-plagued federal government is going to expand the program and start moving low-income women to better neighborhoods en masse.
"It's not enough to simply move families into different neighborhoods," Donovan said. Instead, new ways must be found to help families "break the cycle of poverty that can quite literally make them sick." He did not mention specific proposals.
Public health experts have long thought that living in poor neighborhoods could ruin a person's health, but this study put the idea to a rigorous test.
Here's how it worked: Women believed to be about the same in most respects were randomly assigned to one group or another and then followed through time, in a model customarily seen in pharmaceutical studies. That makes it more scientifically rigorous than most research linking health problems to a social environment.
The study's good design "provides a basis to infer cause and effect" between poverty and bad health, said Dr. Robert Califf, a noted Duke University cardiologist who is leading a massive study on neighborhoods and health outcomes.
The research was led by Jens Ludwig, a University of Chicago professor of public policy. It was published in Wednesday's New England Journal of Medicine.
The experiment started as a $70 million HUD project in Baltimore, Boston, Chicago, Los Angeles and New York. It morphed into a health study after a variety of other government agencies and private foundations pitched in with an additional $17 million more.
"In terms of scale, it's not soon or ever to be repeated," said Dr. Robert Whitaker, a Temple University pediatrician who was a study co-author.
The study involved women living in public housing in neighborhoods where 40 percent or more of residents were poor _ areas like many of those on the South Side of Chicago or in the Bronx in New York City. The women all had children and were considered heads of households.
From 1994 to 1998, nearly 1,800 of them were offered vouchers to subsidize private housing, but the vouchers were only good in higher-income neighborhoods where fewer than 10 percent of the people were considered poor. They were required to live there at least a year.
The rest of the women were divided into two groups. One group got vouchers they could use in any neighborhood. The other women did not receive vouchers, with the expectation that they would stay put.
Ten years later, women in the study were weighed and gave a blood sample to check for diabetes.
The women who moved to richer areas had the lowest rates of extreme obesity and diabetes. The difference suggests that moving to a better neighborhood could help at least 1 in 25 women. Or, in other terms, a person's risk of diabetes or extreme obesity dropped by about 20 percent by moving to a higher-income neighborhood.
(However, even the women who moved were not exactly models of health. About 14 percent of them were extremely obese, which is twice the national average for women.)
The study has some notable flaws.
Because it did not start out looking at health, the women's medical condition and weight were not checked at the outset. The researchers believe the women in the different groups were about the same, because they matched up on more than 50 other indicators, such as age, race, employment and education. But that is an assumption.
Also, only about half the women offered a chance to move to a more prosperous zip code did so. And many who did move left after a year.
What's more, the study was not designed to answer what it is about more affluent neighborhoods that would cause someone to be healthier. But the authors listed four theories:
_ The availability of healthier food is worse in lower-income neighborhoods.
_ Opportunities for physical exercise are scarcer, and fear of crime can make people afraid to jog or play in parks.
_ There may be fewer doctors' offices and other medical services.
_ The long-term stress of living in such an environment may alter the hormones that control weight.
Some of those theories were supported by some women who live in the kind of situation targeted in the study.
Vickie Webb lived in the projects in Durham, N.C., for several years before a housing agency helped relocate her and her husband to a better neighborhood.
"There was too much violence, too much going on in the `hood. It wasn't safe," said Webb, who was not part of the study.
Annie Ricks, who lives with her 14-year-old son and two grandchildren in a public housing unit on Chicago's South Side, was not involved in the study either. But she said efforts like the HUD experiment should be expanded.
Local housing authorities paid for her to relocate to the South Side last year as part of its demolition plans for high-rise tenements. But Ricks lost her child-care job after the move, and says her new neighborhood is worse.
At her old building, Ricks could walk across the street to a supermarket. In her new neighborhood, without a car, she has to take public transportation to get groceries or go to the doctor, and Ricks says there's more crime.
"I feel like it would be a blessing" to be able to move to a wealthier area, she said.
Associated Press writers Alicia Chang in Los Angeles and Lindsey Tanner in Chicago contributed to this report.