Last year, you could barely keep that hot supplement in stock, and now it’s collecting dust in the storeroom. Meanwhile, you’re fielding endless questions about a vitamin no one cared about just a few months back. Thank the ever-evolving world of research and today’s quick-hit media machine for consumers’ fickle supplement-purchasing patterns.

To help you make sound supplement-ordering decisions this year, we asked leading integrative practitioners to examine four of the top consumer health concerns and the best-selling supplements for each between October 2009 and October 2010, based on data from Schaumburg, Ill.-based market-research firm SPINS. We also scoured recent research and asked our experts to weigh in and offer their recommendations for the four conditions. The result? A comprehensive guide to the 15 supplements every retailer should know about now.