In a bid to stay safe under the sun, many in Hong Kong are depriving themselves of essential vitamin D. The sun-safe message has been heard loud and clear, particularly in Hong Kong. With warm temperatures most of the year and awareness that sun damage can lead to skin cancer and premature ageing, many stay covered up no matter what. Yet, in the past few years, research reports have shown that vitamin D - produced in the skin when exposed to ultraviolet light - is found to be at dangerously low levels in many people around the world. Vitamin D promotes the body's absorption of calcium, a mineral that helps keep bones and teeth strong. It also regulates calcium levels in the blood, and levels of the mineral phosphorus, which also helps to promote healthy bones and teeth. In adults, a deficiency can lead to the weak bone condition osteoporosis and, in children, rickets - soft bones. According to The Nutrition Source's online report from the Harvard School of Public Health, about one billion people worldwide have inadequate levels of vitamin D in their blood, and deficiencies can be found in all ethnicities and age groups. Research conducted over the past decade suggests that vitamin D plays a much broader disease-fighting role than once thought. Being 'D-ficient' may increase the risk of a host of chronic diseases, such as osteoporosis, heart disease, some cancers, multiple sclerosis and infectious diseases, such as tuberculosis and even the seasonal flu. 'The latest science suggests that for chronic disease prevention, we need much more vitamin D than these older government guidelines recommend,' the Harvard report says. Doctors from Central Health Medical Practice in Hong Kong have been paying close attention to the vitamin D status of its patients. Doctors Sarah Borwein, Emily Gibson and Rebecca Lau say in a practice report in April this year that a study released in 2008 found that men with low levels of vitamin D appeared to have an increased risk of heart attack compared with men with more than twice this amount. Furthermore, 'rising amounts of autism seem to have occurred since advice regarding sun avoidance became common place; and it is postulated that vitamin D deficiency may play a role here', the report says. Officially, 'D' is labelled a vitamin, but it is in fact converted by the kidneys into a hormone that has important effects on many of our cell processes. Vitamin D is absorbed in small quantities from food, but the vast majority of it is made from ultraviolet radiation. 'There is still a need for further trials and research before we can say for certain vitamin D is a casual factor in the development of serious conditions such as multiple sclerosis or cancer,' the doctors say. Some recommendations say just five to 15 minutes, three days a week in the sun - with sunscreen on your face, but nothing on arms and legs - is enough for a vitamin D boost. But to be sure, speak to your doctor about your vitamin D levels.