London ? Senior citizens are important engines of society, not dependent burdens, according to an international study on aging released Tuesday that shows one in 10 people in their 70s still works.

People in their 60s and 70s continue to play a vital role in the economy as many report feeling healthier and choosing to reject a quiet retirement, the study from Oxford University’s Institute of Aging shows.

“The future of old people is not penury or dependence. They have become turbos rather than the brakes of our community,” said Clive Bannister, managing director of HSBC Insurance, which asked the institute to conduct the study so it could learn about consumer behavior.

Researchers interviewed more than 21,000 people between the ages of 40 and 79 in about 20 countries for the largest study of its kind. The aim was to explore attitudes about life in the elder years and retirement.

Global demographic trends have shifted in recent years as life expectancy has increased and birth rates decreased, said Professor Sarah Harper, director of the institute.

Contrary to the commonly held belief that older people are draining state resources, the study indicates they are more independent and active in social and economic life than previously thought.

“People in their 50s and 70s are very different now than they were before. They are making a tremendous contribution to society,” Harper said.

Older people volunteer for more than 13 million hours per year, which in Britain alone amounts to $3.1 billion worth of unpaid work.

Older people in the U.S. have reported being healthier than the global average, with 72 percent of 70- to 79-year-olds reporting feeling in good health. One-fifth of people in this age group continue to work.

Seniors who postpone retirement also boost tax revenues. Nearly half of individuals in their 40s and 50s surveyed said they would work for as long as possible and more than a third of people in their 60s are still working now. Eleven percent of people in their 70s still work.

Harper said governments and societies should do more to ensure that policies and attitudes enable older people to continue contributing. She encouraged employers to value older workers by recruiting and retraining employees over the age of 50.

The places surveyed include the United Kingdom, the United States, Turkey, the Philippines, Mexico, South Africa, Russia, Germany, Saudi Arabia, Japan, Singapore, Malaysia, India, South Korea, Brazil, Canada, Denmark, China, Taiwan, France and Hong Kong.