Grandparents who care for their grandchildren live up to five years longer than those who don't, remarkable new research has found.

The research indicates caring for grandchildren increases life expectancy significantly more than being healthy, active and independent.

It also has more impact on life expectancy than being diagnosed with one or more chronic or severe illnesses late in life.

"It is quite striking," says Edith Cowan University's Doctor David Coall, one of the study's authors.