Dietary supplements — the vitamins, herbs and botanicals that you'll find in most grocery stores — are everywhere. More than half of U.S. adults over 20 take them, spending almost $50 billion on vitamins and other supplements in 2021. Yet decades of research have produced little evidence that they really work. Aaron Scott talks to Dr. Jenny Jia about the science of dietary supplements: which ones might help, which ones might hurt, and where we could be spending our money instead.