Labs at the largest hospital in Newfoundland and Labrador are being overwhelmed by unnecessary requests for vitamin D testing, doctors say.

New research has raised hopes that vitamin D could extend and improve people's lives. Scientific studies have suggested it may protect against cancer, diabetes and even depression.

Called the "sunshine vitamin" because exposure to ultraviolet rays produces it in the human body, vitamin D has been the subject of growing discussion about whether people should take supplements.

Endocrinologist Christopher Kovacs, who works at the Health Sciences Centre in St. John's, told CBC News patient requests to have their vitamin D levels tested are clogging up the labs, and he said it's often an unnecessary test.

"So many of the requests are unnecessary, or there's a more logical way of dealing with it," Kovacs said. "If you're concerned about your vitamin D level, go on a supplement for several months then check the level to see if you need more than that. If we did that, it would really cut down on a lot of the current requests."

Kovacs said he does think most people in Newfoundland and Labrador should take a vitamin D supplement, because of the province's northern climate, but most people don't need their levels tested.