Calories in Onion

About Onion Nutrition

Onions are one of the most widely used vegetables in cuisines worldwide, prized for their ability to add depth and flavor to dishes. Part of the allium family alongside garlic and leeks, onions contain unique sulfur compounds that provide both their pungent aroma and many health benefits. Available in yellow, white, red, and sweet varieties, each offers slightly different flavors.

With 40 calories per 100 grams, Onion provides 1.1g of protein,9g of carbohydrates, and 0.1g of fat.

Macronutrient Breakdown

• Protein: 1.1g - 11% of calories
• Carbohydrates: 9g - 90% of calories
• Fat: 0.1g - 2% of calories

Health Benefits of Onion

• Rich in quercetin, a powerful antioxidant with anti-inflammatory properties
• Contains sulfur compounds that may support heart health
• Good source of vitamin C for immune function
• Provides prebiotic fiber that feeds beneficial gut bacteria
• May help regulate blood sugar levels
• Contains chromium which helps with insulin function

How to Eat Onion

Onions can be eaten raw in salads and sandwiches, sautéed as a base for countless dishes, caramelized for sweetness, grilled for smoky flavor, or pickled for tang. Cooking mellows their sharp flavor. To reduce tears when cutting, chill onions first or cut near a vent. Different varieties suit different uses - red for raw, yellow for cooking, sweet for grilling.

Selection and Storage

Choose firm onions with dry, papery skins and no soft spots or sprouting. Store whole onions in a cool, dark, well-ventilated place (not the refrigerator) for up to 2 months. Once cut, wrap tightly and refrigerate for up to 10 days. Sweet onions have shorter shelf life.

Dietary Considerations

Onions are very low in calories (40 per 100g) and naturally vegan and gluten-free. They're suitable for most diets including keto and paleo. Some people have difficulty digesting raw onions due to FODMAPs - cooking improves digestibility. Those with acid reflux may want to limit intake.