I very much doubt the statement.
"Studies have shown those over 60 who are in the sun 15 to 20 minutes a couple times a week between 11am and 2pm when the sun produces the most D should be able to generate the vitamin D needed to support optimal health"
That amount of time provides enough vitamin D to have a minimal level for a young person who is at the equator AND young
AND not obese
AND has light skin
AND it is summer
AND has lots of skin exposed to the sun
AND is lying down
AND is not wearing sunscreen.
Data at http://vitamindwiki.com/tiki-index.php?page_id=1689