Piper Jaffray analyst Sean Naughton says a new documentary, "Supplements and Safety" set to air on January 19 on PBS, is likely to bring additional negative media attention to the category. The documentary will likely highlight unscrupulous behavior by some producers as well as question the validity of taking many of the products sold in the sector, Naughton tells investors in a research note. The analyst expects sector sales to be challenged amid the negative industry reports. He lists the most impacted stocks, in order, as Vitamin Shoppe (VSI), Natural Grocers (NGVC), Sprouts Farmers Markets (SFM) and Whole Foods (WFM).