MoMo Productions/Getty Images It can be easy to think you get plenty of vitamin D when you live in a country bathed in sunshine, but the reality is more complicated. Almost one in four Australian adults have vitamin D deficiency. Vitamin D supplements are now one of the most commonly used complementary medicines. So what is vitamin D? And do you need to take it as a supplement? It functions like a hormone Vitamin D is a fat-soluble vitamin that plays a crucial role in maintaining overall hea