Vitamin D is best known for building strong bones, but it may also lead to a longer life, according to recent studies. In a recent analysis of more than 18 studies involving nearly 60,000 people, those who took vitamin D supplements had a 7 percent reduction in mortality from all causes compared with those who didn't take the vitamin. The numbers improved slightly for people who took vitamin D for three years or more. They had an 8 percent lower risk of dying. Doses were kept between 300 to 2,000 international units (IU) per day.