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Onion: Fiber Breakdown, Calories, and Daily Value

Dietary fiber, prebiotic inulin, and antioxidant quercetin. A complete nutritional profile with mindful preparation tips for delicate stomachs.

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🌿 1 medium onion (~100 g / 3.5 oz)

Vegetables

🌿 Dietary Fiber

1 medium onion (~100 g / 3.5 oz) 1.7 g

Soluble

0.9 g (53%)

Insoluble

0.8 g (47%)

Per 100g: 1.7 g

🎯 Daily Norm

% of DV of 30g / day (1 serving)

🔥 Calories & Energy

1 medium onion (~100 g / 3.5 oz) 40.0 kcal

Per 100g: 40.0 kcal

40 calories per 100 g — a light vegetable that adds volume and flavor without many calories.

⚡ Glycemic Index (GI)

1 medium onion (~100 g / 3.5 oz) 12 (Very low)

Per 100g: 12

GI 10–15: barely raises blood sugar; the glycemic load of a serving is about 0.6.

💡 Popular onion varieties

Yellow onion fiber is about 1.5–2 g per 100 g; the difference between varieties is small.

🟡 Yellow storage onion: classic flavor, more quercetin in the outer layers, and fructans for the microbiome.

🔴 Red onion: milder and sweeter, contains anthocyanins; if prone to gas or bloating, it can still feel heavy raw.

⚪ White / spring onion: more tender and juicy, but fructans and irritating sulfur compounds are still present.

✨ Choose fresh onion and prepare it in a way that feels comfortable for your gut: raw if your stomach tolerates it easily, gently cooked for maximum softness.

⚡ Quick Fiber Calculator (Onion)

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🟢 You ate 1.7 g of fiber — that is 6% of your daily norm (30 g)!

How Fiber and Nutrients in Onion Support Daily Wellness

How onion helps with weight control

Water and fiber add volume without many calories, and its very low GI can help you stay satisfied longer.

Satiety Score

★ ★ ★ ☆ ☆ 3.5 / 5.0

Moderate fullness: high water, low calories

Caloric Density 40 calories

Low calorie density

Effects on digestion: benefits and risks

Raw onion contains pungent volatile sulfur oils that can stimulate stomach acidity, while its fermentable fructans may cause gas in sensitive individuals. Gently cooking, roasting, or stewing onions softens these compounds and makes them far easier on the digestive tract.

Stomach «Softness» Scale

Irritating 2 / 10 (Raw onion frequently triggers acidity and bloating; cooking greatly improves comfort) Ideal

GI Stimulation Score 🌿 Gut rhythm after cooking Cooked onion is gentler on the lining, but fermentable fructans can still encourage gas if your gut is sensitive.

Microbiome fermentation and a glycemic shield

🩸 Microbiome fuel
Good gut bacteria enjoy inulin and fructans: they help these bacteria grow and produce butyrate.

🛡️ Butyrate production
Butyrate feeds colon cells and helps support the gut lining.

🌿 Glycemic shield
Onion fiber and its very low GI barely spike blood sugar.

Prebiotic value

Fiber 1.7 g Inulin & fructans (FODMAP)

Feeds friendly bacteria

Glycemic buffer 🛡️ Very low GI, but moderate portions if prone to bloating No risk of sharp sugar drop

Culinary Physics

Raw vs Thermal Processing

How fiber properties and bioavailability change in Onion

🥗 Raw form

Raw onion (maximum fresh compounds)

Intact structure: Intact cells require active chewing, and raw onion preserves vitamin C and volatile sulfur compounds.
Quercetin and antioxidants: Most quercetin is in the outer colored layers; it may help support blood vessel health and reduce oxidative stress.
Slow breakdown: Fiber slows carbohydrate absorption, but fructans can cause bloating in sensitive guts.

🔥 Thermal processing

After cooking

Gentler on the lining: Stewing or roasting lowers pungent sulfur oils that can provoke acidity and irritation.
Better nutrient availability: Cooking softens texture and can help absorb some antioxidants, especially with a little oil.
Easier digestion: Cooked onion is usually more comfortable for the stomach, but fructans remain and can cause gas if your gut is sensitive.

Culinary Constructor & Alternatives

Best Food Combinations with Onion

Ready-made balanced combinations from the catalog

🥗 Fiber Plate Constructor

Cozy Dinner

Savory onion base for lentil or buckwheat soup

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Onion Ingredient

+1.7 g

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Carrot Ingredient

+2.8 g

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Lentils Ingredient

+11.85 g

🟢 Total in plate: 16.4 g of fiber (55% of norm)

💡 Quick prep: Onion is a standout source of prebiotic inulin. Sauté it slowly to bring out its natural sweetness.

🏆 Similar High-Fiber Options

Compare the amount of fiber in other products:

🥗 Beet 2.8 g / 100g 🌶️ Bell Pepper 2.5 g / 100g 🥦 Broccoli 2.6 g / 100g 🥕 Carrot 2.8 g / 100g