Onions (Allium cepa) are bulb-shaped vegetables that grow underground and are part of the allium family, closely related to chives, garlic, scallions, shallots, and leeks. They are grown worldwide and are a staple in many cuisines, used as a flavoring or main ingredient. Onions are versatile and can be prepared in numerous ways, including baking, boiling, grilling, frying, roasting, sautéing, or eating raw in salads.
Nutritionally, raw onions are low in calories, with about 38 calories per 3.5 ounces (100 grams). They are about 90% water, 8.6% carbohydrates, and 1.9% fiber, with small amounts of protein and fat. Onions are a good source of vitamin C, folate, vitamin B6, and potassium. Different types of onions, such as yellow, red, and white, offer varying nutritional profiles. For example, red onions have more antioxidants, while yellow onions have the highest amount of quercetin. Even onion peels are rich in nutrients like fiber, carbohydrates, and minerals, and are being explored for biomedical and pharmacological applications.
