Walk into your grocery store’s produce aisle or stroll through the local farmers market and you’ll likely see a plethora of onion options—there are actually 21 different types! Onions are a vegetable species within the genus allium, along with similar aromatic bulbs like garlic, leeks, chives, and shallots. (While these other well-known veggies aren’t onions themselves, they are in the same vegetable family and yield many health benefits, too.) Whole onions should last in your pantry or other cool, dry, dark place (not the fridge) for about two weeks—but don’t store them next to potatoes, which emit gas and moisture that can quickly spoil onions. If you have leftover onion that’s already been cut, pop it in a resealable bag in the fridge to stay fresh for about a week (you can also store it in a container in the freezer). Here are some of the top nutritional benefits that onions provide. If you’re looking for more reasons to pick up an onion or two next time you’re at the store, you’re in the right place.
Nutritional Benefits of Onions
Onions help improve heart health.
Eating onions can have a healthy impact on your cardiovascular system. Specifically, research has found that the polyphenol called quercetin that’s in onions helps reduce high blood pressure and triglyceride levels. Darker-colored onions, like red onions and chartreuse onions, contain the highest amounts of quercetin. Research from the American Chemical Society has also found that the “tearless onion” can help protect against heart disease.
Onions are rich in antioxidants for immune health, anti-inflammation, and more.
Onions are packed with disease and free-radical-fighting antioxidants, which help repair and protect damaged cells in your body. They’re one of the best sources of flavonoids (including quercetin), phytochemicals with powerful antioxidant properties. According to a review published in the Journal of Agriculture and Food Chemistry, onions contain at least 25 different flavonols. “Red and yellow onions are richer in those antioxidants than other types of onions. In fact, yellow onions may contain almost 11 times more antioxidants than white onions,” says Sara Peternell, MNT, board-certified holistic nutritionist specializing in family nutrition. A diet rich in antioxidants can help reduce inflammation and thwart free-radical damage, which leads to a strong immune system and better overall health.
Onions may reduce cancer risk.
There’s been some interesting research conducted on how onions may play an important role in helping to prevent cancer. A study out of the University of Guelph concluded that red onions, specifically, are the most effective at reducing colon and breast cancer cells. This is once again due to the high levels of quercetin and anthocyanin (another type of antioxidant flavonoid). Another study published in Cancer Prevention Research found that one to seven servings of allium veggies, like onions, is rich in organosulfur and flavonols—compounds that have been found to have tumor-inhibiting components.
How to Cook With Onions
Raw yellow onions tend to be the sweetest variety, making them a great addition to salsas. Cooked yellow onions make a savory base for soups, stews, and sauces. Onions are also delicious on their own, roasted, grilled, or sautéed. Top sandwiches and burgers with grilled (or raw!) onions to up the zest factor. For a tangy burst of flavor—and beautiful color—add pickled red onions to grain bowls, fish or pork tacos, or alongside any meaty main. If you’re a little uneasy about adding onions into your at-home menu, start by keeping the cooking process simple. Weis recommends slicing the onions into discs, brushing them with olive oil, seasoning with salt and pepper, and grilling both sides. Check out these creative recipes—starring the humble onion—that are bursting with flavor and nutrients.
Caramelized Onion Apple Tart
These easy caramelized onion apple tarts pack a lot of flavor without too much work, thanks to frozen puff pastry. Serve as an appetizer or alongside a salad for a full meal. Get the recipe.
Deeply Caramelized Onion Dip
Patience is the key to this addictive dip: Cook the onions low and slow, stirring frequently—no shortcuts allowed. Serve with thick-cut potato chips and crisp veggies. Get the recipe.
Tapenade and Red Onion Pizza
The salty tapenade goes well with the sweet, sautéed onions. Besides, you can never go wrong with pizza. Pair with a peppery arugula salad to round out the meal. Get the recipe.
Rich French Onion Soup
This French classic is easy to make and takes half the time. What’s not to love? If you don’t like Swiss cheese, you can try gruyere instead. Get the recipe.
Should Anyone Avoid Onions?
It’s true that onions aren’t for everyone. If you feel like onions don’t sit well with you, it’s not all in your head. Some people are very sensitive to the oligosaccharides, a fructan found in onions. Karen Graham, RDN, a functional medicine dietitian, says that onions can be problematic for many people, causing gas, bloating, constipation, and diarrhea, and that about 30 percent of people tested for food intolerances in her practice have an issue with onions. The green tops of scallions are not usually a problem, she says, so that may be a good place to start to add onion flavor and nutrients into meals.
