Bronzed Aussie myth wilting in shade

http://news.smh.com.au/bronzed-aussie-myth-wilting-in-shade/20071218-1hpl.html

Hospitals are again treating children with rickets while their casualty wards struggle with an epidemic of broken bones.

Cancer and diabetes may also be increasing because more and more Australians are staying out of the sun and not getting the vitamin D they need to stay strong and healthy.

Some figures suggest 70 per cent of the population lacks the vitamin D produced when sunlight hits the skin.

"I think a lot of us have been worried about it for a long time, but have just realised how widespread it is over the last five to 10 years," osteoporosis specialist Peter Ebeling said of vitamin D deficiency.

---

More sun is healthy, despite cancer risk

http://news.smh.com.au/more-sun-is-healthy-despite-cancer-risk/20080108-1kqe.html

A little more sunshine might help you live longer, according to a study suggesting that for some people health benefits from the sun outweigh the risk of skin cancer.

Sunlight spurs the body to produce vitamin D but fear of skin cancer is keeping many people in the shade and depriving them of an important protection from a range of diseases, researchers said.

"The skin cancer risk is there but the health benefits from some sun exposure is far larger than the risk," said Johan Moan, a researcher at the Institute for Cancer Research in Oslo, who led the study. "What we find is modest sun exposure gives enormous vitamin D benefits."

A number of studies have found protective effects from higher vitamin D intake for some cancers and ailments such as rickets, osteoporosis and diabetes, Moan said. Certain foods contain vitamin D but the body's main source comes from the sun.

The researchers calculated that given the same amount of time spent outside, people living just below the equator in Australia produced 3.4 times more vitamin D than people in Britain and 4.8 times more than Scandinavians.

This means even though rates of internal cancers such as colon cancer, lung cancer, breast cancer and prostate cancer rise from north to south, people in the sunnier latitudes were less likely to die from the diseases, the researchers said.

"The current data provide a further indication of the beneficial role of sun-induced vitamin D for cancer prognosis," said Richard Setlow of the US Department of Energy's Brookhaven National Laboratory, who worked on the study.

Getting more vitamin D - which helps the body's immune system work properly - is also critical for people living in places like Scandinavia where long winters and short days during the year limit sun exposure, Moan added.

In Norway, Moan estimated that doubling the sun exposure for the general population would also double the number of annual skin cancer deaths to about 300 but that 3,000 fewer people would die from other cancers.

"The benefits could be significant for people in other countries as well," he said in a telephone interview. "I would be surprised if they were different."

Moan, whose findings were published in the Proceedings of the National Academy of Sciences, recommended daily sun exposure for about half the time it takes a person to get sunburn.

Another way to get more vitamin D could be designing sunscreen that blocks long ultraviolet wavelengths that trigger the deadliest forms of skin cancer while letting through short ultraviolet wavelengths that produce the vitamin, the researchers said.

---

Studies confirm 'Out of Africa' theories

http://news.smh.com.au/studies-confirm-out-of-africa-theories/20080222-1tw0.html

Two big genetic studies confirm theories that modern humans evolved in Africa and then migrated through Europe and Asia to reach the Pacific and Americas.

The two studies also show that Africans have the most diverse DNA, and the fewest potentially harmful genetic mutations.

One of the studies shows European-Americans have more small mutations, while the others show Native Americans, Polynesians and others who populated Australia and Oceania have larger ranges of genetic changes.

The studies, published in the journal Nature, paint a picture of a population of humans migrating off the African continent, and then shrinking at some point because of unknown adversity.

Later populations grew and spread from this smaller genetic pool of founder ancestors - a phenomenon known as a bottleneck.

Populations that remained in Africa kept their genetic diversity - something seen in many other studies.

"The one thing that I think we cannot say from this study is that any one person's genome is any healthier or evolutionarily fit than another person's genome," said Carlos Bustamante of Cornell University in New York, who worked on one study.