So you're making a salad or sandwich, which type of onion should you use? Obviously the red variety (or purple onion as some call it) has a much more intense flavor, which people tend to either love or hate. But when it comes to nutrition and if that is what's most important to you, then who wins between a red onion vs. yellow onion vs. white onion? Is there a significant difference?Hands down, the red onion wins for antioxidants. In fact they have an ORAC value which is two-thirds higher (66.6% exactly) than yellow and 76% higher than white. What makes red particularly nutritious are the higher amounts of flavonoids, the polyphenol compound quercetin (a potent anti-inflammatory), and the 25+ different anthocyanins they contain (1). Anthocyanins are a category of antioxidants and they're found in the reds and purples of vegetables and fruits. That's why you don't want to "over peel" the outer layers away from a red onion, since those dark purple layers are the part which contain the most antioxidants.But what does the rest of their nutritional profile look like? If you look at 1 cup chopped (about 160 grams) all colors - whether red, yellow, or white - contain roughly the same amount of vitamin C (15% to 20% of your daily value). Their calcium content is identical (4% of daily value) as well as their iron content (2%), dietary fiber (3%), sodium (5 to 6 mg), protein (1 to 2 grams) and calories (60 calories).So there's no reason to choose red versus white or red versus yellow onions for pretty much any other category of nutrition. That means your decision should be based on taste and antioxidants. If you enjoy the taste of red/purple onions, then it's the best onion for your health.
USDA Database for the Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2 - Prepared by Nutrient Data Laboratory, Beltsville Human Nutrition Research Center (BHNRC), Agricultural Research Service (ARS), U.S. Department of Agriculture (USDA) - May 2010