Onions are the third most popular vegetable in America. Here's why that's good.

Onions are the third most popular vegetable in the United States, and Americans consume about 350 semi-truck loads full of them every day, per research from New Mexico State University's College of Agricultural, Consumer, and Environmental Sciences. 

While we enjoy many different onion varieties, the most popular ones include yellow onions, red onions, white onions, pearl onions, shallots, scallions (called green onions), sweet onions and Spanish onions. 

Though having to slice or dice an onion can certainly be something to cry about, it's a good thing so many onion types are available because including onions in one's diet is absolutely good for overall health. 

Are onions good for you? 

Onions are a nutrient-dense vegetable and various types contain protein and vitamins and minerals such as magnesium, phosphorous, zinc, niacin, thiamin, vitamin A and biotin. "Onions also contain potassium, which supports hydration and reduced inflammation; plus folate, which supports neurotransmitter function and mood regulation," says Dr. Uma Naidoo, director of nutritional and lifestyle psychiatry at Massachusetts General Hospital and the Harvard-trained nutritional psychiatrist behind “Calm Your Mind with Food."

Onions have a surprising amount of natural sugar content as well, with one yellow onion containing about 8 grams. This helps onions offer a unique flavor profile and "a good balance of savory and sweetness," says Vijaya Surampudi, a physician and clinical nutritionist at UCLA Health in California. She notes that onions are also "rich in phytonutrients and antioxidants," which may improve blood pressure and reduce inflammation and cholesterol. 

Onions are also high in allyl sulfides, which research shows can improve one's risk of developing cancer and heart disease. "And onions are high in vitamin C, which is great for skin health; and manganese, which helps the body create connective tissue," says Kristina Cooke, a registered dietitian with the Academy of Nutrition and Dietetics. She adds that onions also provide a great source of dietary fiber - "about 3 grams of fiber for 1 cup diced," she says - which can help with digestive health, weight management and blood sugar regulation.

Why are onions so popular? 

Independent of such health benefits, onions also have the advantages of being versatile and flavorful and are popular as a garnish or ingredient in recipes and dishes like French onion soup, blooming onions, casseroles, onion rings, French onion dip and salsa. They're also a popular sliced or diced topping for burgers, sandwiches, tacos, hot dogs, salads, soups, curries and chili. "Onions are incredibly diverse culinarily and can be roasted, grilled, pickled, caramelized or eaten raw," says Surampudi. 

She explains that onions are also highly accessible, easy to grow, and have been passed down in countless recipes and utilized "for many centuries." They also have the advantage of being "part of the allium family, which tends to be among the most economical and versatile kitchen staples."

Why do onions make you cry?  

But it isn't all good news as onions also have a distinct odor that many find unpleasant; and they're known for causing bad breath. "Onions can also contribute to digestive issues such as bloating, nausea and diarrhea for some people," says Surampudi.

More:Bad breath is common but preventable. Here's what causes it.

The disadvantage onions are most commonly known for, however, is that they can make you cry. This occurs because, "when a raw onion is cut, it releases enzymes and sulfoxides that interact to create a gas that then irritates the eyes, nose and throat in a way that signals to the brain to release tears to clear the irritant," explains Naidoo. 

White, yellow and red onions have higher concentrations of these enzymes and sulfoxides, which is why one is more likely to get teary eyed when preparing those onion varieties and less likely when preparing varieties like shallots and scallions. 

If one can push through the tears or simply enjoy onions someone else has prepared, however, they are a great addition to one's diet. "Consider adding extra flavor by adding fresh, raw onions as a topping," suggests Cooke, "or use them to flavor soups, salads and stews."