I recently took my 6 month old to the doctor and he suggested that I give my daughter a Vitamin D supplement to prevent  rickets ( bone disorder) and fluoride because we live on well water.
I  looked into both for more information. First off I looked at the AAP policy and what I got out of it is that they do not want to suggest going out in the sun for short periods of time so that have it worked out with a company to suggest the only Vitamin D supplement on the market made by a baby formula maker. It also has artificial flavors and sweetners. NO THANKS!   
In looking for alternatives my Herbalist and Naturopath suggested Cod liver oil only in the fall and winter months. Then I became concerned about the mercury.  They said a  brand called Nordic Naturals is third party screened to make sure that no mercury or toxins are in the oil. The Cod Liver oil offers the vitamin D naturally and includes omega 3 and DHA benefits.
Next, fluoride....I stopped using fluoride several years ago and now I remember why after looking into it again.  Learn what I discovered at  www.sunshineorganics.net [1]
It will blow you away!