Onions, particularly red and yellow onions, are fantastic natural sources of the well-studied flavonoid quercetin. According to the University of Maryland Medical Center, quercetin acts like an antihistamine and an anti-inflammatory, and can guard against heart disease and cancer.
Surprisingly dense in nutrients: One medium-sized onion also contains a surprising number of additional nutrients. This includes approximately 20 percent of our recommended daily intake of the essential antioxidant vitamin C, as well as varying amounts of protein, fiber, potassium, magnesium, manganese, calcium, iron and most of the B vitamins.
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