What did randomized, controlled human trials find about the ways we may—or may not—benefit from eating onions? Onions are potentially a good source of antioxidants, which, interestingly, are concentrated in the outer layers just beneath the papery peel. White onions, for example, contain more than ten times the antioxidants in the outer layer compared to the inner core. Unfortunately, most people discard the most nutrient-rich outermost layers, “thus losing a valuable part of the antioxidant-rich material.” In general, yellow onions have more antioxidants than white onions. Red onions beat the...