Does Echinacea Work Against Colds?

What's better for a cold: vitamin C or echinacea? — Rob C., St. Louis, MO

The sheer breadth of scientific literature supporting vitamin C's ability to fight the common cold could fill a small library. Indeed, a recent study found that people who took 500 milligrams of vitamin C daily had 34 percent fewer colds than those who took less. The number of studies devoted to echinacea, on the other hand, wouldn't fill a three-ring binder.Bottom line: Choose either vitamin C or Ester-C (a nonacidic version of vitamin C that's gentler on the stomach).

— Mark Moyad, MD, the Phil F. Jenkins director of preventive and alternative medicine at the University of Michigan Medical Center