Onions are bulb-shaped vegetables that grow underground.
Onions may have several health benefits, mostly due to their high content of antioxidants and sulfur-containing compounds.
They have antioxidant and anti-inflammatory effects and have been linked to a reduced risk of cancer, lower blood sugar levels, and improved bone health.
Commonly used as a flavoring or side dish, onions are a staple food in many cuisines. They can be baked, boiled, grilled, fried, roasted, sautéed, powdered, or eaten raw.
Onions vary in size, shape, and color, but the most common types are white, yellow, and red. The taste ranges from mild and sweet to sharp and spicy, depending on the variety and season.
Onions can also be consumed when immature, before the bulb reaches full size. They are then called scallions, spring onions, or summer onions.
Nutrition facts about Onions.
Raw onions are very low in calories, with only 40 calories per 3.5 ounces (100 grams).
By fresh weight, they are 89% water, 9% carbs, and 1.7% fiber, with tiny amounts of protein and fat.
The main nutrients in 3.5 ounces (100 grams) of raw onions are:
Calories: 40
Water: 89%
Protein: 1.1 grams
Carbs: 9.3 grams
Sugar: 4.2 grams
Fiber: 1.7 grams
Fat: 0.1 grams
Carbs
Carbohydrates make up about 9–10% of both raw and cooked onions.
They consist mostly of simple sugars, such as glucose, fructose, and sucrose, as well as fiber.
A 3.5-ounce (100-gram) portion contains 9.3 grams of carbs and 1.7 grams of fiber, so the total digestible carb content is 7.6 grams.
Fibers
Onions are a decent source of fiber, which accounts for 0.9–2.6% of the fresh weight, depending on the type of onion.
They are very rich in healthy soluble fibers called fructans. In fact, onions are among the main dietary sources of fructans
Fructans are so-called prebiotic fibers, which feed the beneficial bacteria in your gut.
This leads to the formation of short-chain fatty acids (SCFAs), such as butyrate, which may improve colon health, reduce inflammation, and cut your risk of colon cancer.
SUMMARY
Onions consist mostly of water, carbs, and fiber. Their main fibers, fructans, can feed the friendly bacteria in your gut, though they may cause digestive problems in some people.
Onions contain decent amounts of vitamin C, folate, vitamin B6, and potassium, which provide a number of benefits.
Onions are rich in plant compounds and antioxidants, especially quercetin and sulfur-containing compounds. Colorful varieties, such as yellow or red ones, pack more antioxidants than white ones.
Onions have antioxidant and anti-inflammatory effects. They may lower blood sugar levels, improve bone health, and reduce the risk of several types of cancers.
