🧅 Red Onion Nutrition Facts per 100g: Calories, Carbs, Vitamins & Health Benefits

🌱 Introduction: Why Red Onions Are So Good for You

Red onions are more than just a flavour booster — they’re low in calories, rich in nutrients, and packed with beneficial plant compounds. Commonly used raw in salads or cooked in a wide range of dishes, red onions contribute vitamins, minerals, and antioxidants that support overall health.

This guide breaks down red onion nutrition per 100g, explains the key health benefits, and shows how they fit into a balanced diet.

⭐ Recommended Products — Using & Preparing Red Onions

• Sharp Kitchen Knife
A sharp knife makes slicing red onions easier and helps reduce crushing, which can release more irritant compounds.
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• Chopping Board
A stable chopping board provides a safe surface for preparing onions and other vegetables.
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• Airtight Storage Container
Useful for storing chopped red onion in the fridge and reducing odour spread.
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🧅 Red Onion Nutrition Facts (Per 100g, Raw)

Approximate values:

• Calories: 40 kcal
• Carbohydrates: 9.3 g
• Sugars: 4.2 g
• Fibre: 1.7 g
• Protein: 1.1 g
• Fat: 0.1 g
• Water: ~89%

Red onions are naturally low in fat and calories, making them ideal for calorie-controlled diets.

🧂 Vitamins & Minerals in Red Onions (Per 100g)

Red onions contain a useful range of micronutrients, including:

• Vitamin C – supports immune health and skin
• Vitamin B6 – important for metabolism and nervous system function
• Folate (Vitamin B9) – supports cell growth and repair
• Potassium – helps regulate fluid balance and blood pressure
• Manganese – supports bone health and metabolism

While not extremely high in any single vitamin, red onions contribute valuable nutrients when eaten regularly.

🌿 Antioxidants & Plant Compounds

Red onions are especially rich in quercetin and anthocyanins, which give them their deep red-purple colour.

These compounds are linked to:

• Reduced inflammation
• Improved heart health
• Protection against oxidative stress

Red onions contain more antioxidants than white or yellow onions.

❤️ Health Benefits of Red Onions

💓 Supports Heart Health

Potassium and flavonoids may help support healthy blood pressure and circulation.

🛡️ Anti-Inflammatory Properties

Quercetin is known for its anti-inflammatory effects, which may support joint and immune health.

🦠 Immune Support

Vitamin C and antioxidants help support the body’s natural defences.

🌱 Gut Health Support

Dietary fibre helps support digestion and healthy gut bacteria.

🍽️ Are Raw or Cooked Red Onions Healthier?

Both forms have benefits:

Raw red onions

• Higher vitamin C and quercetin content
• Stronger flavour and crunch

Cooked red onions

• Easier to digest
• Sweeter taste
• Slight loss of heat-sensitive vitamins

Including both raw and cooked onions provides the best balance.

⚖️ Red Onions and Weight Management

Thanks to their:

• Low calorie content
• High water percentage
• Fibre contribution

Red onions add flavour and bulk to meals without significantly increasing calorie intake.

🚫 Common Nutrition Myths About Red Onions

• ❌ “Red onions are high in sugar”
• ❌ “Onions have no nutritional value”
• ❌ “Cooked onions are unhealthy”

In reality, red onions are nutrient-dense for their calorie level.

🧠 Key Takeaway

Red onions are a low-calorie, nutrient-rich vegetable that provides fibre, vitamins, minerals, and powerful antioxidants. At just 40 calories per 100g, they support heart health, immunity, and digestion while adding flavour and colour to meals.