I remember my foot doctor told me that in Canada, we do not have enough Vitamin D which may cause osteoporosis, and sunlight is the best provider of Vitamin D. She told me to get direct sunlight in the mornings for 20 minutes where the sun appears. She stressed that Vitamin D cannot penetrate glass, so if I sit in the sitting room with the glass patio doors closed, even though the sun shines on me, I won't get any Vitamin D. I researched this on the web just today, and almost all articles tell the same thing.
Here is one of them, which I would like to share with you. So remember, even though you sit in your car with the sun shining on you through closed windows, you will not get any Vitamin D. The benefits of Vitamin are many many indeed.http://www.NaturalNews.com/003069.html
It's really interesting!