This seems to be a study based in statistics and correlations, and I spontaneously started wondering if the increased mortality rates among those using suppleme

This seems to be a study based in statistics and correlations, and I spontaneously started wondering if the increased mortality rates among those using supplements with large doses were similar people who lived sedentary lifestyles. That is, using supplements in a vain attempt to offset not going outdoors all too often (i.e. physical exercises for at least 30 minutes a day), or simply in order to offset bad conscience. Those will probably have added health risks due to their lifestyle, and voila, high D vitamin == added mortality rates. The problem with these studies is to exclude all factors poisoning the results, and I think this could be one of the relevant ones that are also hard to track down accurately.