I've worked at two health food stores.
One only carried a limited range of tried and tested supplements, and was staffed by qualified herbalists. Most things were done by special order, if a customer really wanted something odd.
The other had 15 times as many supplements, from every supplier imaginable. They only paid $7.25 an hour, so of course no one in that department was qualified. The most popular products, were drug test cleanse kits, and vitamin B to cut Cocaine. Ladies made a B-Line to get the newest Dr. Oz supplement, like Raspberry Ketones, or Green Coffee Bean Extract, and never looked at the food he has also suggested. The customers also were used to cashiers answering questions, about the thousands of supplements. Would not work there again.