They are a staple in just about every American kitchen – and they do more than just flavor your food.

We’re talking about onions, of course.

Dr. Manny Alvarez, senior managing health editor of FoxNews.com, received this question from a viewer:

My husband told me that he read something about onions being a superfood. Is that true?

Alvarez said this is one instance where you should be saying, “Yes, dear” – because your husband is right.

Onions actually offer superior health benefits to some of our favorite superfoods, like pomegranates, green tea and red wine, he added.

Alvarez checked in with Chris Kilham, the Medicine Hunter, for a second opinion.

"Onions are especially high in beneficial antioxidants including the super-antioxidant, quercetin, which is useful for the heart, for the immune system (and) for many, many things in the body,” Kilham said. “I would make the claim that onions are among the healthiest of all foods you could possibly eat, and that if you eat an onion every day - and I’m not talking raw, you can cook it, prepare it any way you like - you will do far more for your health than eating lots of the super fruits that are available.”

So remember – an onion a day may keep the doctor away.

If you have a question for Dr. Manny Alvarez, email him at Dr. Manny@foxnews.com.