A new study has revealed that high smoking rates in the past, combined with widespread obesity, continue to chip away at US life expectancy compared to other wealthy nations.
Over the past 25 years, life expectancy after 50 has risen in the United States, but at a slower rate than in countries like Japan and Australia, said the National Academy of Sciences report.
The gap sounded the alarm among government researchers because the United States spends more on health care than any other country, said the study which examined mortality records in 21 countries.
Men in the US showed an increase in life expectancy of 5.5 years between 1980 and 2006 for an average lifespan of 75.64 years, while US women's lifespans expanded from 77.5 to 80.7 years.
"Three to five decades ago, smoking was much more widespread in the US than in Europe or Japan, and the health consequences are still playing out in today's mortality rates," said the report.
"Smoking appears to be responsible for a good deal of the differences in life expectancy, especially for women."
Cigarette smoking also appears to have dented life expectancy in Denmark and the Netherlands, the report said, noting those two nations showed "lower life expectancy trends than comparable high-income countries."
Globally, women tended to pick up smoking later than men, and started quitting later than men, too.
In 1980, average US life expectancy for women at age 50 was 30.6 years, similar to women in nine other industrialized countries.
But in 2007, women in America gained just 2.5 years for a 33.1 year life expectancy at age 50, compared to gains of 6.4 years in Japan, 5.2 years in Italy and 3.9 years on average among the nine other rich countries.
"Similarly, life expectancy in Japan is expected to improve less rapidly than it otherwise would, because of more-recent high smoking rates," said the study.
In a country where one in three people are overweight, obesity could also be to blame for "a fifth to a third of the shortfall in longevity in the US compared to other nations," said the researchers.
"And if the obesity trend in the US continues, it may offset the longevity improvements expected from reductions in smoking."
Women in Japan had the highest life expectancy -- 85.98 years -- just edging out France (84.39) and Italy (84.09) based on the most recent data, while men in Australia are living the longest -- 79.27 years -- followed by Sweden (78.92) and Canada (78.35).