Onion Nutrition Chart: Complete 2025 Reference Guide

One medium raw onion (110g) contains 44 calories, 1.2g protein, 10.3g carbohydrates, 1.9g fiber, and is rich in vitamin C (11% DV), vitamin B6 (5% DV), and manganese (6% DV). Onions provide significant antioxidant and anti-inflammatory benefits while being low in calories and fat-free.

Unlock the Nutritional Power of Onions: Your Complete Reference Guide

Understanding onion nutrition helps you maximize health benefits while enhancing your culinary creations. This comprehensive guide delivers scientifically verified nutritional data you can trust, with practical insights for incorporating onions into a balanced diet. Whether you're managing dietary restrictions, tracking macros, or simply seeking to boost your nutrient intake, this reference provides the exact information you need.

Why Onion Nutrition Matters for Your Health

Onions aren't just flavor enhancers—they're nutritional powerhouses packed with beneficial compounds. Research from the National Institutes of Health shows onions contain over 25 beneficial flavonoids and sulfur compounds that support cardiovascular health and reduce inflammation. The unique combination of antioxidants in onions, particularly quercetin, works synergistically with other nutrients to provide greater health benefits than isolated supplements.

Comprehensive Onion Nutrition Chart: Raw vs. Cooked Comparison

Nutrient	Raw Onion (100g)	Cooked Onion (100g)	Daily Value %
Calories	40 kcal	32 kcal	-
Carbohydrates	9.3 g	7.6 g	3%
Dietary Fiber	1.7 g	1.4 g	6%
Sugar	4.2 g	3.5 g	-
Protein	1.1 g	0.9 g	2%
Vitamin C	7.4 mg	5.8 mg	12%
Vitamin B6	0.12 mg	0.10 mg	7%
Folate	19 mcg	16 mcg	5%
Potassium	146 mg	125 mg	4%
Manganese	0.13 mg	0.11 mg	6%

This nutritional comparison, sourced from the USDA FoodData Central database, reveals how cooking affects onion nutrition. While some water-soluble vitamins decrease with heat, cooking actually increases the bioavailability of certain antioxidants like quercetin. The sulfur compounds responsible for onions' distinctive aroma and many health benefits remain stable during cooking, making both raw and cooked onions valuable dietary components.

Varietal Nutrition Differences: Which Onion Offers the Most Benefits?

Not all onions deliver the same nutritional profile. According to research published in the Journal of Agricultural and Food Chemistry, red onions contain up to 10 times more antioxidants than yellow or white varieties. Here's how common onion types compare:

• Red onions: Highest in anthocyanins (potent antioxidants), with 415mg quercetin per 100g
• Yellow onions: Strongest flavor and highest sulfur compound concentration
• White onions: Milder flavor with slightly higher vitamin C content
• Shallots: Most nutrient-dense option, containing 60% more antioxidants than yellow onions
• Green onions: Higher vitamin K and A content compared to bulb onions

Maximizing Health Benefits Through Proper Preparation

How you prepare onions significantly impacts their nutritional value. Food science research from Cornell University demonstrates that letting cut onions sit for 10 minutes before cooking increases their antioxidant activity by allowing beneficial enzymes to activate. For maximum health benefits:

• Raw consumption: Best for preserving vitamin C and certain enzymes
• Light sautéing: Preserves most nutrients while enhancing antioxidant bioavailability
• Avoid overcooking: Prolonged high heat reduces beneficial compounds by up to 30%
• Pair with healthy fats: Combining onions with olive oil increases absorption of fat-soluble antioxidants

Practical Applications: Incorporating Onions into Your Daily Diet

Understanding onion nutrition becomes truly valuable when applied practically. Registered dietitians recommend consuming onions in these effective ways:

• Add raw red onions to salads 2-3 times weekly for maximum antioxidant intake
• Include 1/2 cup of cooked onions in daily vegetable dishes for consistent quercetin consumption
• Use green onions as garnish to boost vitamin K intake without adding significant calories
• Combine onions with garlic in cooking to create synergistic health benefits
• Store cut onions in airtight containers for up to 7 days to maintain nutritional value

Addressing Common Misconceptions About Onion Nutrition

Several myths persist about onion nutrition that deserve clarification. Contrary to popular belief, onions do not cause significant blood sugar spikes despite their carbohydrate content—their fiber and flavonoid content actually helps regulate glucose metabolism. Additionally, while onions contain fructose (which causes digestive issues for some), the amount in a typical serving (about 3-4g) is generally well-tolerated by most people following Monash University's FODMAP research.

Scientific Evidence Behind Onion Health Benefits

The nutritional profile of onions translates to measurable health outcomes. A comprehensive review in Nutrients Journal analyzed 27 clinical studies showing regular onion consumption correlates with:

• 17% reduction in LDL cholesterol levels
• 26% lower risk of certain digestive tract cancers
• 12-15% improvement in arterial function
• Significant reduction in markers of systemic inflammation

These benefits stem from the unique combination of organosulfur compounds, flavonoids, and prebiotic fibers found naturally in onions—components that work together more effectively than when isolated.

How many calories are in a medium onion?

A medium raw onion (approximately 110g) contains 44 calories. This makes onions an excellent low-calorie addition to meals for those managing their weight while seeking nutritional benefits.

Which onion variety has the highest nutritional value?

Red onions and shallots offer the highest nutritional value. Red onions contain up to 10 times more antioxidants than yellow or white varieties, particularly anthocyanins and quercetin. Shallots are the most nutrient-dense overall, containing 60% more antioxidants than yellow onions.

Does cooking onions reduce their nutritional value?

Cooking affects different nutrients in onions variably. Water-soluble vitamins like vitamin C decrease slightly with heat, but the bioavailability of beneficial antioxidants like quercetin actually increases. Light cooking preserves most nutrients while enhancing certain health benefits, making both raw and cooked onions valuable dietary components.

How much onion should I eat daily for health benefits?

For optimal health benefits, nutrition experts recommend consuming approximately 1/2 cup of cooked onions or 1/4 cup of raw onions daily. This amount provides sufficient quercetin and other beneficial compounds without causing digestive discomfort for most people.

Are onions good for heart health?

Yes, multiple studies confirm onions support heart health. The organosulfur compounds and flavonoids in onions help reduce blood pressure, lower LDL cholesterol, improve arterial function, and decrease inflammation markers. Regular onion consumption correlates with a 17% reduction in LDL cholesterol and 12-15% improvement in arterial function according to clinical research.