More on how much vitamin D is needed

I've written about vitamin D before, and I take a daily supplement (400 IUs in the summer, 1000 IUs in the winter).

Here is some more information which illustrates why many people may not be getting enough. A glass of fortified milk has 100 IUs, but a fair-skinned person in shorts and a tank top will produce 1000 IUs per minute in midday summer sun. Most Americans receive insufficient UV light in the winter to naturally produce any vitamin D.

Read more here.