Cratox AI
Reviewed by Cratox Nutrition Team · Updated August 13, 2026

Cratox team note

Onions contain 40 kcal and 1.1 g of protein per 100 g, making them a low-calorie addition to meals. Use raw onions to enhance salads or sandwiches, providing flavor and a crunchy texture.

Onions, raw vs Carrots, baby, raw: nutrition compared

Nutrient (per 100 g)Onions, rawCarrots, baby, raw
Calories40 kcal41 kcal
Protein1.1 g0.8 g
Carbohydrates9.3 g9.1 g
Fat0.1 g0.1 g
Fibre1.7 g2.7 g
Sugar4.2 g0 g
Sodium4 mg62.7 mg

All values per 100 g. Source: USDA FoodData Central.

Onions, raw - nutritional information

Onions, raw

🔥 40 Calories
💪 1.1g Protein
9.3g Carbohydrates
🥑 0.1g Fat

Onions, raw provides 40 kcal per 100 g, with 1.1 g of protein, 9.3 g of carbohydrates and 0.1 g of fat. 1 slice of Onions, raw (38 g) provides about 15 kcal.

At a glance

A fast summary built from the current nutrition profile per 100g.

Category
Vegetables
Onions, raw
Energy density
Light
40 kcal per 100g
Macro energy profile
Carb-led
10% Protein · 88% Carbohydrates · 2% Fat
Glycemic profile
Low GI
GI 10 · GL 1
Notable signals
Low in fatLow in sugarLow in sodiumUSDA data

Nutritional Information

40
kcal/100g
Protein
1.1g
Carbohydrates
9.3g
Fat
0.1g
Glycemic Index:
10

Nutritional Information (per 100g)

NutrientAmount per 100 g
Calories40 kcal
Protein1.1 g
Carbohydrates9.3 g
Fat0.1 g
Fiber1.7 g
Sugar4.2 g
Sodium4 mg

USDA data · USDA FoodData Central

Calories per portion

PortionWeightCalories
1 slice38 g15 kcal
1 cup160 g64 kcal
1 tbsp chopped10 g4 kcal
1 large piece150 g60 kcal
100 g100 g40 kcal

Portion weights: USDA FoodData Central

Portion calculator

Calories
40 kcal
Protein
1.1 g
Carbohydrates
9.3 g
Fat
0.1 g
Fiber
1.7 g
Sugar
4.2 g
Sodium
4 mg

All values are computed from the per-100 g nutrition data (source: USDA).

About Onions, raw

Onions, scientifically known as Allium cepa, are a staple vegetable with a long history of cultivation, dating back thousands of years. They are believed to have originated in Central Asia, particularly in Iran and Pakistan, and have since become a global culinary favorite. Onions are used in a variety of dishes, from salads to soups and sauces, and are cherished for their distinctive flavor, which can range from sweet to pungent depending on the variety.

Nutritionally, raw onions are low in calories, providing about 40 calories per 100 grams. They are primarily composed of carbohydrates, with a notable amount of natural sugars, and contain a small amount of protein and virtually no fat. Onions are rich in vitamins and minerals, particularly vitamin C and various antioxidants, which contribute to their health benefits. They are often included in diets for their potential anti-inflammatory and heart-health-promoting properties, making them a versatile ingredient in both raw and cooked forms.

Health Benefits

Rich in antioxidants that help combat oxidative stress.
May reduce the risk of certain cancers due to their high sulfur content.
Supports heart health by helping to lower cholesterol levels.
Promotes digestive health thanks to their fiber content.
May aid in blood sugar regulation, beneficial for diabetics.
Contributes to immune system support through vitamin C.
Contains anti-inflammatory properties that may help reduce inflammation.
May improve bone health due to its potential to increase bone density.
Supports skin health with its antibacterial properties.
May enhance respiratory health due to its anti-allergic effects.

Recommended Food Pairings

🥗
Onions and tomatoes - the acidity of tomatoes complements the sweetness of onions.
🥗
Onions and chicken - enhances flavor and adds moisture to chicken dishes.
🥗
Onions and cheese - the sharpness of cheese balances the pungency of onions.
🥗
Onions and garlic - a classic combination that amplifies flavors in many cuisines.
🥗
Onions and bell peppers - great for stir-fries, adding sweetness and crunch.

How to Consume

Serving size
Recommended serving is 100g, approximately 1 medium onion.
Frequency
Recommended frequency is 2-3 times per week.
  • Use raw in salads for a crisp texture.
  • Sauté onions to bring out their natural sweetness.
  • Add to soups for depth of flavor.
  • Caramelize onions for a rich, sweet taste.
  • Mix with other vegetables for a nutritious stir-fry.

Selection & Storage

How to choose:

  • Select firm onions with dry, papery skin.
  • Avoid onions with soft spots or signs of sprouting.
  • Choose onions that are heavy for their size.
  • Look for onions with a strong aroma for freshness.
Storage
Store in a cool, dry place, away from sunlight and moisture.
Shelf life
Onions can be stored for 2-3 months in optimal conditions.

Warnings & Contraindications

  • ⚠️Individuals with irritable bowel syndrome (IBS) may experience discomfort from onions.
  • ⚠️Those allergic to Allium species should avoid onions.
  • ⚠️Excessive consumption may cause digestive upset or flatulence.

Frequently Asked Questions

How many calories does Onions, raw have?

Onions, raw provide approximately 40 calories per 100 grams, making them a low-calorie food choice that can be included in various diets without contributing significantly to daily caloric intake.

Is Onions, raw healthy?

Yes, raw onions are considered healthy due to their rich content of vitamins, minerals, and antioxidants. They are low in calories and high in fiber, making them beneficial for digestion and overall health.

How should Onions, raw be stored?

Raw onions should be stored in a cool, dry place, ideally in a mesh bag or basket to allow for air circulation. Avoid storing them in plastic bags, which can trap moisture and lead to spoilage.

What are the benefits of eating Onions, raw?

Eating raw onions provides numerous health benefits including improved heart health, enhanced immune function, and potential cancer-fighting properties. Their high antioxidant content also supports overall wellness.

How much Onions, raw can I eat per day?

A typical serving size of raw onions is about 100 grams, or one medium onion. Consuming 2-3 servings per week is often recommended to enjoy their health benefits without digestive discomfort.

How many calories are in 1 slice of Onions, raw (38 g)?

1 slice of Onions, raw (38 g) has about 15 kcal — 0.4 g protein, 3.5 g carbohydrates and 0 g fat (calculated from the USDA values per 100 g).

How many calories are in 1 cup of Onions, raw (160 g)?

1 cup of Onions, raw (160 g) has about 64 kcal — 1.8 g protein, 14.9 g carbohydrates and 0.2 g fat (calculated from the USDA values per 100 g).

How many calories are in 1 tbsp chopped of Onions, raw (10 g)?

1 tbsp chopped of Onions, raw (10 g) has about 4 kcal — 0.1 g protein, 0.9 g carbohydrates and 0 g fat (calculated from the USDA values per 100 g).

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