PubMed is produced by the U.S. National Library of Medicine and provides citations for millions of biomedical articles.
For Dietary Supplements, the following Medical Subject Headings (MeSH) will result in the retrieval of many relevant articles:
In the Limits area you can limit your search to Complementary Medicine which can be found under the Subset category.
Advisories and recalls about drugs, natural health products and medical devices from Health Canada.
500 mg calcium supplement tablets, with vitamin D, made from calcium carbonate, maltodextrin, mineral oil, hydroxypropyl methylcellulose, glycerin, Vitamin D3, polyethylene glycol, and carnauba wax. These supplements are distributed by Nature Made Nutritional Products.
By Ragesoss (Own work) [GFDL (www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons
From US Food and Drug Administration (FDA)