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Antarctic researchers risk bone loss

Low sun

Sunlight can be a scarce commodity in Antarctica and that's affecting vitamin D levels in some researchers (Image: Australian Antarctic Division)

Scientific researchers spending winter in Antarctica might be at increased risk of osteoporosis unless they take vitamin D supplements, new research suggests.

A pilot study presented last week at the Scientific Committee on Antarctic Research meeting in Hobart, suggests some researchers who spend the winter in Antarctica have low levels of vitamin D, which is making their bones weaker.

"Their bone may resorb more calcium and get weaker which can lead to a potential increase in osteoporosis in the long term," says researcher Dr Jeff Ayton, chief medical office of the Australian Antarctic Division.

Vitamin D is a hormone produced by the action of solar ultraviolet radiation on the skin and is essential for a number of processes including bone metabolism.

Lack of exposure to sunlight decreases vitamin D synthesis and increases bone turnover and bone loss.

Ayton says expeditioners who spend the winter in Antarctica have very little exposure to sunlight for seven to nine months.

But in summer they are at high risk of sunburn unless they cover up with hats and sunscreen.

Ayton and colleagues studied the vitamin D levels and skeletal response to sunlight deprivation in 57 healthy adults (with an average age of about 38 years) during their winter in Australia's Antarctic program.

Participants were also followed up after leaving Antarctica and returning to a more temperate climate.

Bone resorption, but not formation, was elevated during the period of sun deprivation, Ayton and colleagues report.

But they have yet to determine the long-term effect on bones, such as the increased risk of osteoporosis.

It may be that researchers need to receive supplements of vitamin D, says Ayton, or screened for vitamin D levels before they head south.

Ayton says medical researchers are concerned that many people in the general population may have subclinical vitamin D deficiency depending on the latitude of where they live.

And he says the lower acceptable limit of vitamin D may be revised upwards.

"It may increase from the current level of 25 nanomols per litre to a higher level," he says.

Tags: health, biology, chemistry