Study: Vitamin D reduces risk of premature death

Most of the vitamin D people have is made in their skin.

TORONTO GLOBE AND MAIL

Taking vitamin D has been found to have a new benefit: It appears to be a life extender, according to a new study.

Researchers who pooled the results of 18 separate experiments conducted in several industrialized countries reported that people who were given a vitamin D supplement had a 7 percent lower risk of premature death than those who were not.

The pooled results were from experiments conducted in the United States, Germany and Britain, among other countries, and included more than 57,000 participants.

For reasons that are not yet fully understood, those who received vitamin D had a lower chance of dying prematurely than those given dummy pills, or placebos, in the experiments, said the study published in the Archives of Internal Medicine.

“Mechanisms by which vitamin D supplements would decrease all-cause mortality are not clear,” said the study’s authors, Philippe Autier of the International Agency for Research on Cancer in Lyon, France, and Sara Gandini of the European Institute for Oncology in Milan, Italy.

Earlier studies

Earlier research has indicated that vitamin D deficiencies are associated with higher risks of contracting major illnesses such as cancer, which account for 60 percent to 70 percent of deaths in high-income countries. The study speculates that the vitamin, which is used in organs and tissues throughout the body, may cut death rates by inhibiting the proliferation of cancerous cells.

Vitamin D is also known as the sunshine vitamin, because it is produced in naked skin that is exposed to strong sunlight.

Many medical experts believe people living in northern countries have a chronic deficiency of the vitamin in winter, when the weak sunlight does not lead to creation of the nutrient in skin.

Although most of the vitamin D people have is made in their skin, it is also available in supplement form and in some foods.

The European study tracked the participants in the various experiments for an average period of 5.7 years, taking note of whether those dying had been given the vitamin.

There were 4,777 deaths from all causes among the group.

Those experiencing the lower risk of dying took daily doses of vitamin D ranging from 300 to 2,000 international units, with the average 528 IU.

Most commercially available multivitamins contain between 400 and 600 IU.

Some foods — for example, oily fish like salmon and sardines — are a natural source of the vitamin.

Milk is commonly fortified with 100 IU per cup.

Advice

In a separate editorial in the journal, Edward Giovannucci of the Harvard School of Public Health and one of the world’s leading researchers on vitamin D, said evidence of the nutrient’s health effects are so strong that doctors should start testing their patients’ vitamin D levels and treating those with deficiencies.

The new study “adds a new chapter in the accumulating evidence for a beneficial role of vitamin D on health,” Dr. Giovannucci said.

“From a broader public health perspective, the roles of moderate sun exposure, food fortification with vitamin D and higher-dose vitamin D supplements for adults need to be debated,” he said.

Giovannucci also said North Americans may be inadvertently contributing to their vitamin D deficiencies through sun avoidance in an attempt to prevent skin cancer.