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Red, Yellow, White & Beyond: A Nutritionist On The Benefits Of Onions & How She Eats Them

Red Onions
Image by Tatjana Zlatkovic / Stocksy
November 7, 2020

When you look at the bases of many recipes, there's a particular vegetable that crops up across different cuisines and different cooking styles: onions. Partially because they come in so many varieties, onions can add a good base of flavor to any dish or can be added as a brightening topping—it all comes down to how you use them.

But how do you decided what onions to grab for what recipe? And is there one variety that reigns supreme for health benefits? We were curious, so we touched base with chef and nutritionist Serena Poon, C.N., CHC, CHN.

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Picking the right onion is about flavor and texture.

"Onions are versatile vegetables that can add character to a wide array of dishes," says Poon. "I let the unique flavor and texture of each onion guide which type I will use for each recipe."

In terms of flavor, yellow onions are the most adaptable—think of them as your everyday any-recipe onion, and don't mistake them for white onions, which have a much sharper onion flavor. The sweet varieties are, as you may guess, sweeter than the other varieties, and red onions are actually pretty similar to yellow onions, though they're slightly crisper.

But there's another cue you can follow: your gut. And we don't just mean your intuition.

"One thing to note is that some people experience digestive discomfort from eating certain types of onions," says Poon. This can also extend beyond just what type of onion you pick toward how you cook it: Some people may be better off eating slow-cooked onions than raw chopped bits—but you have to listen to your body to figure that out. "If eating a certain type of onion causes you to feel bloated, or digestive discomfort, then maybe that particular variety or method of cooking isn't for you."

What are the health benefits of onions?

Onions are something of an underrated ingredient when it comes to health, but they're actually a great source of a variety of nutrients—that flavor punch they provide is almost just an added bonus.

"No matter which type of onion you select, you'll be delivering a nice dose of antioxidants to your body," shares Poon. Onions of all varieties contain a free-radical-fighting flavonoid that's known as quercetin. According to Poon, "Quercetin has also been shown to support cardiovascular health1, potentially protect against some cancers2, and lower blood pressure and cholesterol3."

The other beneficial dietary component of onions come from their structure: They're a good source of prebiotics (the food that fuels the healthy bacteria in our gut). "Prebiotics and probiotics are at the cornerstone of my Culinary Alchemy philosophy," Poon explains to mindbodygreen. "So much of your digestive, immune, and even brain health are founded on having a balanced digestive microbiome."

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Is there a "healthiest" onion?

"No matter which type of onion you select, you'll be delivering a nice dose of antioxidants to your body," she says—but there is one type of onion that has extra free-radical-fighting power.

"Red onions contain anthocyanins," she shares, which are the phytochemicals that give them their red hue." According to medical research4, this particular phytochemical has "anti-diabetic, anti-cancer, anti-inflammatory, antimicrobial, and anti-obesity effects" and are also known to help prevent cardiovascular diseases. 

That being said, that doesn't mean red onions are definitively the "healthiest"—they just have some bonus nutrients, but all onions provide essential nutrients and prebiotics for your overall health.

How a nutritionist uses onions in everyday cooking.

So if picking the perfect onion doesn't have a definitive always answer, how do you decide what to grab at the grocery store? Beyond just going with what you like best for flavor and what works best with your gut, what you plan to prepare can also be a good place to take a cue from for shopping. And though white, yellow, red, and sweet varieties may be what comes to mind when you picture an onion, there are other varieties that technically fall under the umbrella that bring their own special flavor to the party:

  • Red onions: "Red onions taste delicious when grilled; you can eat them plain or enjoy them on sandwiches or kebabs," says Poon. "I also love using raw red onion slices as a crunchy salad topping or for pickling."
  • White onions: The most common use of these onions is in super-traditional bases: "These onions are the standard for use in mirepoix, a blend of carrots, celery, and onion that form the basis for soups, sauces, and many traditional dishes" she explains.
  • Yellow onions: As we mentioned, yellow onions are one of the most flexible varieties, but there are some particular places they shine: "These easy-to-find onions are my go-to for heartier dishes like stews or roasts."
  • Sweet onions: When building flavors with sweet onions, it's best to lean into their natural profile: "Sweet onions taste great when caramelized and used to top dishes or in onion marmalades," shares Poon.
  • Shallots: "I love cooking with shallots," she says. "I regularly use these uniquely flavored onions in a variety of dishes including vinaigrettes, dressings, caramelized, confit, or smashed potatoes." Because of their mellow but distinct flavor and small size, shallots are a great multipurpose onion, too.
  • Spring onions: Since they're easy to regrow, spring onions (also known as green onions, or scallions) have been super popular in 2020—which is lucky because Poon has plenty of suggestions: "I love getting creative with spring onions and will chargrill them, roast them, braise them, and blend them into soups, dips, spreads, or sauces. (Think gremolata, chimichurri, compound vegan butter, or an onion vegan cheese spread.)"
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Adding onions is a great way to give any dish a good strong flavor base, but they're also great for adding prebiotic and antioxidant benefits to your cooking. Picking the best option is more about finding the variety that fits best with what you're cooking (and what agrees with your gut).

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