i do believe vitamin d is important..and most people can get enough from sunshine exposure..but those that are housebound should supplement..and in the North people in the winter should as even if you are out there mght not be enough sushine.
i'n not big on supplementation but if there is a deficiency and you can't get outside..well it's better than getting sick i think
Brenda
Bloom where you are planted.
http://restfultrailsfoodforestgarden.blogspot.com/