They contained “cheap fillers like powdered rice, asparagus and houseplants, and in some cases substances that could be dangerous to those with allergies.” We’re not talking fly-by-night Internet products; these are glossy bottles of so-called Gingko Biloba and Echinacea and Garlic, sold in stores like GNC and Target and Walgreens, with relaxing names like “Herbal Plus” and “Spring Valley”: When you buy a supplement, then, you’re effectively on your own — not just in determining whether the supplement is safe and effective, but even in deciding whether you’re eating what you think you’re eating.