Elderly people who care for others live longer than those who don't, an Australian study has found.

The study was released by Western Australia's Edith Cowan University last week.

It found that grandparents who provide occasional care for their grandchildren live up to five years longer than those who don't.

The research found that half of the elderly people who provided occasional care for grandchildren or other members of the community lived for up to five more years after first being interviewed for the research.

On the other hand, half of those who did not provide care died within five years of the initial interview.

Dr David Coall, a researcher from the university's School of Medical and Health Sciences, said the study showed that caregiving helped improve longevity among older people.

"This research shows the positive link between caregiving and a longer lifespan in older people," he said in a media release.

"Previous research points to helping behaviour as a stress buffer which involves, for example, the hormone oxytocin, which can strengthen bonding between people.

"This link could be a mechanism deeply rooted in our evolutionary past, when help with childcare was crucial for the survival of the human species."

The benefits of caregiving, he said, extended beyond looking after grandchildren. He said: "Older people who cared for their own adult children or other members of the community showed the same increase in longevity."

However, separate research conducted by Dr Coall's team found that elderly people who cared for their grandchildren on a full-time basis exhibited negative impact on their physical and mental health.

He said there was no strict limit on the amount of time an elderly person should care for another person.

"It is very important that every individual decides for himself what 'moderate amounts of help' means," he added. "As long as you do not feel stressed about the intensity of help you provide, you may be doing something good for others, as well as for yourself."

XINHUA