WELLINGTON, May 13 (Xinhua) -- While it's long been known that a little sunshine can spread happiness, researchers in New Zealand have found that it can also save the lives of pneumonia patients.
Medical scientists have found that vitamin D, which is absorbed through the skin and produced with exposure to sunlight, is a major factor in the survival rate of pneumonia patients.
Researchers at Waikato University collaborated with doctors at Waikato Hospital, both Hamilton-based institutions, to study blood samples of 112 patients admitted to the hospital with pneumonia during the winter.
They found that those with severe vitamin D deficiency 17 of the patients were more likely to die within a month, compared with patients with normal or slightly low vitamin D levels.
Dr Bob Hancox, of the hospital's department of respiratory medicine, said five of the 17 died, a 29-percent mortality rate, compared with four deaths among the 95 patients with higher vitamin D levels, a 4-percent mortality rate.
"The analysis confirmed that the difference in mortality rates between the two groups was very unlikely to be due to chance," Hancox told Xinhua.
Vitamin D deficiency was a concern around the world, Hancox said.
"Sunlight is the main source of vitamin D, so it tends to be a winter problem in temperate climates when people spend a lot of time indoors. But it occurs in all countries and vitamin D deficiency is believed to be a major problem worldwide.
"There is accumulating evidence that we need vitamin D to help fight infections, such as pneumonia as we have shown, as well as improve bone health," he told Xinhua.
"What is not yet clear is whether we can do anything about it. We don't know whether treating people with vitamin D supplements would help to prevent or treat respiratory infections. This is what we need to find out now."
Dr Ray Cursons, of the Biological Sciences department at Waikato University, said patient age, sex, additional health conditions, and other prognostic factors did not affect the research outcome, although researchers still could not establish a causal link between vitamin D deficiency and mortality in the patients.
Waikato Hospital D respiratory specialist Dr Noel Karalus said it was not yet known whether giving patients vitamin D supplements after their admission to hospital with respiratory tract infections would alter outcomes.
"It may transpire that vitamin D helps us avoid infection rather than cure it once established."
Cursons said the best source of vitamin D was sunlight as dietary sources such as fatty fish and cod liver oil did not contain enough vitamin D.
"There is still some controversy regarding the optimal daily allowance of vitamin D. How much we absorb through the skin depends on sun exposure, skin type and geographical latitude. M ori and Pacific Islanders absorb less because of their darker skin, and people in colder climates also have lower levels of vitamin D. "
Pneumonia is the single largest cause of death in children worldwide, killing an estimated 1.6 million children under the age of five each year, according to the World Health Organization.
The research findings are published in the journal Respirology, published by the Asian Pacific Society of Respirology, this month.