Why Your Supplement Brand Isn’t Selling on Amazon & Walmart If you sell collagen, protein powder, probiotics, vitamins, or any wellness product online, you already know something most shoppers never think about: the supplement category on Amazon and Walmart is brutal.  Hundreds of sellers are fighting for the same three or four keywords, and the big brands with unlimited ad budgets usually win the top spots. So if your listing looks fine, your product actually works, and your reviews are decent — but sales still aren’t coming in — you’re not doing anything “wrong.” You’re probably just fighting the wrong battle. Most supplement sellers lose sales not because their product is weak, but because their listing, keywords, and ad spend aren’t built for how competitive this category really is. This guide breaks down exactly where supplement brands lose money on Amazon and Walmart, and what actually fixes it.