Vitamin D increases life expectancy, study finds

Angela Mulholland, CTV.ca News
Sep. 10 2007 4:12 PM ET

An intriguing new study finds that those who take vitamin D supplements can increase their life expectancies by one to two years.

The study, published in the Archives of Internal Medicine, is just the latest to add to the growing body of evidence that "the sunshine vitamin" is not just good for strengthening bones but also appears to increase survival.

Past studies have suggested that vitamin D deficiencies might be associated with a higher risk of death from cancer, heart disease and diabetes -- illnesses that account for 60 to 70 per cent of deaths in high-income nations.

This study finds that taking extra vitamin D brings health benefits, even in the short term.

This study looked at the results of 18 previously published studies involving a total of 57,311 participants.

Dr. Philippe Autier, of the International Agency for Research on Cancer, Lyon, France, and Sara Gandini, of the European Institute of Oncology, Milano, Italy, analyzed the studies and evaluated doses of vitamin D ranging from 300 to 2,000 international units, with an average dose of 528 international units.

Most commercially available supplements contain between 400 and 1,000 international units.

After an average of 5.7 years, those participants who took vitamin D had a seven per cent lower risk of death than those who did not.

"We had a reduction in all-cause mortality after a follow-up of about six years. So it means that may represent something like an increase of two to three years of your life expectancy," Autier told CTV News.

"With vitamin D, you could say yes, finally, if there is one supplement to take, with all the evidence so far, the best is to take vitamin D -- ordinary doses of vitamin D, not high doses."

The editorial that accompanies the article points out that the study did not consider specific causes of death. The studies were generally short, so the impact of vitamin D was seen on diseases that express themselves in a shorter period of time. For chronic diseases that have a long period of time to develop, the impact of vitamin D would be underestimated by this analysis.

The authors note that it's not clear how vitamin D supplementation lowers death risk. They say it could be that the vitamin inhibits some mechanisms by which cancer cells multiply and grow. Or, it may boost the function of blood vessels or the immune system, they note.

Where the sun don't shine

The editorial notes that vitamin D supplements may simply be compensating for a deficiency that many people appear to have.

"In recent years, an increasing number of researchers from various fields have been arriving at the conclusion that the levels of vitamin D in many people are inadequate for optimal health," the editorial reads.

Heather Chappell of the Canadian Cancer Society says this latest study supports the growing body of evidence of the health benefits of vitamin D. It also supports their recommendations, issued earlier this year, that the entire adult population of Canada begin taking vitamin D supplementation.

"We want to remind Canadians that in Canada, the sun is not strong enough in the fall and winter to produce enough vitamin D. So the Cancer Society recommends that adults start talking 1,000 IU of vitamin D daily.

"The sun's rays become less strong as we move into the fall, so people should start taking a supplement in the fall and winter... probably near the end of September."

Toronto physician, Dr. Linda Rapson says she finds that many of her patients with chronic pain and other ailments are also deficient in vitamin D.

"I have seen people with levels so low that their muscles are weak and they can't get out of a chair easily. After a couple of weeks of taking vitamin D, there is a huge change," she says.

"I think people should be aware vitamin D is essential, that you have to take it. And you don't just take it for a while and you are fine; you have to keep taking it."

With a report from CTV medical specialist Avis Favaro and producer Elizabeth St. Philip