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Onion (Half) Calories
Source of vitamin C and fiber, low calorie
CALORIES
GI
POTASSIUM
FIBER
Onion (Half) Nutrition Facts
Selected: 100 g
40
KCAL / 100G
Carbs
9.3g
· 88%
Protein
1.1g
· 10%
Fat
0.1g
· 2%
Fiber
1.7g
Onion (Half) Vitamins & Minerals
Vitamins
Vitamin C
7.4mg · 8% DV
B6
0.12mg · 7% DV
Folate
19µg · 5% DV
B1
0.05mg · 4% DV
Minerals
Phosphorus
29mg · 4% DV
Potassium ⭐
146mg · 4% DV
Calcium
23mg · 2% DV
Magnesium
10mg · 2% DV
Onion (Half) Glycemic Index
GLYCEMIC INDEX
GLYCEMIC LOAD
Accounts for portion size — a more realistic measure than GI alone.
Is Onion (Half) Processed?
NOVA 1
Unprocessed
1. Unprocessed
2. Minimally Processed
3. Processed
4. Ultra-Processed
NOVA classifies foods into 4 groups by industrial processing. NOVA 1 (unprocessed) is the healthiest.
Does Onion (Half) Contain Allergens?
No known major allergens
Which Diets Is Onion (Half) Good For?
Vegan
✓ Suitable
Vegetarian
✓ Suitable
Gluten-Free
✓ Suitable
Dairy-Free
— Not suitable
Mediterranean
✓ Suitable
Paleo
✓ Suitable
Whole30
— Not suitable
DASH
— Not suitable
Keto
— Not suitable
Low FODMAP
— Not suitable
Onion (Half) Fat Profile
SATURATED
0.03g
MONOUNSATURATED
0.01g
POLYUNSATURATED
0.02g
Omega 6:3 ratio 2:1
Below the ideal 4:1 — a good omega balance.
Foods Similar to Onion (Half)
Onion (Half) — Frequently Asked Questions
How long does half an onion keep after it has been cut?
A cut onion usually keeps for 1-2 days in the fridge if stored in an airtight container. Discard it if it becomes slimy, overly soft, or develops a strong off smell.
Can half an onion be frozen?
Yes, onion can be frozen chopped or sliced. After thawing it loses its crisp texture, so it is best used in soups, sauces, and cooked dishes rather than raw.
Does cooking onion greatly reduce its nutritional value?
High heat and long cooking can reduce some delicate compounds, but onion still adds flavor and fiber to a meal. Gentle cooking without burning is usually the best approach.
Why does onion taste so sharp, and how can I make it milder?
Its pungency comes from natural sulfur compounds released when the onion is cut. Rinsing sliced onion briefly in cold water or soaking it in lemon juice or vinegar can soften the bite.
Is raw onion or cooked onion easier to digest?
Cooked onion is often easier on the stomach because heat softens its texture and flavor. Raw onion can trigger gas, bloating, or discomfort in sensitive people.
What foods pair well with onion for a more balanced meal?
Onion works well with protein-rich foods, legumes, eggs, yogurt-based dishes, and olive oil vegetables. These combinations can make meals more filling while improving flavor.
Is onion a good food before a workout?
It depends on your tolerance, but raw onion is not ideal for many people before exercise because it may cause stomach discomfort. If you want to include it, a small amount of cooked onion is usually easier to handle.
Is it bad to eat onion at night?
For most people, eating onion at night is not harmful. However, raw onion may worsen reflux, bloating, or indigestion in people who are sensitive.
Can onion replace antibiotics when you are sick?
No, onion is a healthy vegetable but it is not a substitute for antibiotics or medical treatment. Suspected infections should be assessed and treated appropriately.
Who should be more careful with onion?
People with IBS, reflux, or a sensitive stomach may react more strongly to onion, especially raw onion. Large portions can make symptoms worse in some individuals.
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Nutrition data compiled from USDA FoodData Central and scientific sources.