Vitamin D and calcium supplements could help older people live longer, according to a new review of existing research.
Scientists from the Aarhus University Hospital in Denmark compared eight randomised, controlled trials that looked at the vitamin D intake of more than 70,000 adults in their 60s and 70s.
They found people who took vitamin D supplements along with their calcium supplements were nine percent less likely to die over a three-year period, compared with people who took no supplements.
However, they found people who took vitamin D alone had no greater chance of survival.
Vitamin D is an essential nutrient that helps our bones absorb calcium. Our bodies produce vitamin D when we are exposed to sunlight, or it can be taken in supplement form.
For every 151 people who took vitamin D and calcium supplements daily, one less person would die, according to the researchers.
"This is the largest study ever performed on effects of calcium and vitamin D on mortality," said study author Lars Rejnmark.
"Our results showed reduced mortality in elderly patients using vitamin D supplements in combination with calcium, but these results were not found in patients on vitamin D alone."
Taking the supplements for less than three years did not appear to affect people's mortality.
The review was based on people taking supplements, however Rejnmark says the results would be similar for people who got their nutrients from their diet.
Rejnmark says calcium and vitamin D is particularly important for post-menopausal women and men from the age of 50.
Carol Nowson, a professor of eating and nutrition at Deakin University, is not surprised by the report, saying plenty of previous studies have shown taking vitamin D, with or without calcium, can increase longevity.
"There is more evidence that if you've got more vitamin D, you're going to live longer, you're going to have lower rates of cardiovascular disease and you're going to have lower rates of cancer," she said.
Professor Nowson would like to see more controlled studies to work out whether it's the vitamin D itself that is making people live longer, or it's lifestyle factors associated with a high vitamin D intake.
"They haven't done an intervention study so it could be that people with higher levels of vitamin D are more likely to be physically active because it's made from the sunlight hitting your skin," she said.
"With any of these studies, it's interesting but exactly how it works we don't actually know."
She recommends getting regular sunlight and having two to three serves of calcium-rich foods, such as milk or yoghurt, each day.
"It's difficult to get enough sunlight in the winter if you live in places like Melbourne because there isn’t much sun, so you can take a supplement," she said.