About two-thirds of the population do not get enough vitamin D, which could increase their risk of depression, diabetes, heart disease and early death.

That's according to research from Intermountain Healthcare, which recently at a national conference is presenting three abstracts that bolster the growing link between vitamin D levels and a wide range of health issues.

While the vitamin has long been known to promote calcium absorption and strengthen bones, it has also been increasingly linked to diseases, from heart disease to autoimmune diseases and some cancers.

Using its vast database of electronic medical records, the Heart Institute at Intermountain Medical Center in Utah posed the questions: What effect do vitamin D levels have on the development of cardiovascular disease? On depression among patients with heart disease? On risk factors for cardiovascular disease, such as diabetes and hypertension?

A lot, according to the abstracts, which will be presented at the American Heart Association's Scientific Conference in Florida. The studies were funded internally by Intermountain Healthcare.

Researchers examined records from 27,000 patients over age 50 that had no history of cardiovascular disease. Patients were considered to have "very low" levels of vitamin D in their blood if it measured below 15 nanograms per milliliter.

When compared with those with normal levels, those with a low level of the vitamin were;

Two times as likely to develop heart failure;

78 percent more likely to have a stroke;

77 percent more likely to die;

45 percent more likely to develop coronary artery disease.

The link between the vitamin and heart disease is just an association for now, said Brent Muhlestein, director of cardiovascular research of the Heart Institute at IMC.

But if it is proved to be true, that would mean that the deficiency is as powerful a risk factor for heart disease as hypertension or high cholesterol.

"This new risk factor is amazingly strong," he said.

The other studies found that among general patients 55 and older, those with very low levels of the vitamin were twice as likely to have diabetes. They were also more likely to have hypertension.

Among older patients with cardiovascular disease, deficiency was associated with having a diagnosis of depression.

It's no surprise individual’s vitamin levels are low: The vitamin is present in few foods and it mainly comes from sun exposure. But sunscreen blocks absorption, and some latitudes reduce the UV radiation exposure needed for vitamin D synthesis.

"We were fascinated that about two-thirds of everybody -- young or old, male or female -- is low on vitamin D," Muhlestein said. "We don't go out in the sun as much as we used to. I don't know that's necessarily bad," he said, referring to the risks of skin cancer.

Instead, he recommends patients learn their vitamin D levels -- it takes a blood test that is typically covered by insurance if it is deemed medically necessary -- and take a supplement.

He put his deficient patients on 2,000 to 5,000 international units a day. The official recommendation, under review by the Institutes of Medicine, is 400 units for people over age 50. But that is just a "drop in the bucket. It's not going to do anything," he said.

In some areas of the country, it takes 2,000 to 5,000 units to maintain adequate levels.

Researchers still need to determine whether boosting levels reduces the risk of heart disease. But Muhlestein noted that supplementation has already been proved to reduce the risk of bone fractures.

"If indeed it turns out vitamin D replacement resolves this added risk, that's fabulous because it's really easy to do," he said.