Down's syndrome cuts tumour growth Down's syndrome may be the key to new anti-cancer treatments, say Harvard University researchers who discovered a key reason why people with the disorder rarely get cancer: they have extra copies of a gene that stops tumours feeding themselves. The DSCR1 gene is crucial in the creation of a protein that suppresses a growth factor tumours use to grow blood vessels. Having an extra copy of the gene results in more of this protein, Reuters reports. Vitamin D reduces cancer risk Having adequate levels of vitamin D may help stop the development of cancer, say US researchers, based on modelling that highlights the role the sunshine vitamin and calcium play in communication between cells. Loss of this communication is 'the first event in cancer', says team leader Cedric Garland of the University of California, San Diego. 'Vitamin D may halt the first stage of the cancer process.' Although more research is needed, the team says people should have their vitamin-D levels tested as part of their annual check-ups, healthday.com reports. Solar-powered intelligence High levels of vitamin D seem to be associated with increased brain power in middle-aged men, say British researchers, based on studies of more than 3,000 men. The link was more pronounced in those over 60. The University of Manchester team found that men with higher levels of vitamin D 'performed consistently better' in tests measuring 'attention and speed of information-processing'. Last year, Dutch researchers found that low levels of the vitamin were associated with a higher risk of depression and other psychiatric problems among older people, AFP reports. Dental filling made using bile acid Chinese and Canadian researchers have developed a material from human bile acid that is tougher and safer for filling dental cavities than current materials mercury or plastic, about which there are concerns of possible toxicity. Bile acid is used to digest fats. The team, led by Julian Zhu, of Shanxi University, converted the acid into a hard, long-lasting plastic that resists cracking, Reuters reports. Japan tops life expectancy table Japanese babies born in 2007 have the longest average life expectancy in the world: 83 years, compared with only 41 for those born in Sierra Leone. Many African nations ranked poorly in the league table released by the World Health Organisation. Fourteen countries have life expectancies of at least 81, including Singapore, Australia, Italy, France, Iceland, Spain and Sweden. Among the 15 countries with life expectancies of less than 50 are Afghanistan, Zimbabwe, Uganda and Nigeria, WebMD reports. Life expectancy in the United States is 78 years - on par with Cuba. Being brainy pays well Being good-looking helps people get better-paid jobs, say US researchers - but not quite as much as being smart. The University of Florida team based its conclusions on analysis of a pool of 191 men and women from the 'Harvard Study of Health and Life Quality'. They found that physical attractiveness had an effect on how much people were paid, their level of education and confidence, WebMD reports.