📊 Nutritional Table (100 g)
Below is the detailed nutritional value per 100 grams onions.
| Nutrient | Amount (100 g) | % RDA |
|---|---|---|
| 🔥 Calories (Energy) | 40 kcal | -- |
| 💪 Protein | 1.1 g | -- |
| 🧈 Fats | 0.1 g | -- |
| 🍚 Carbohydrates | 9.3 g | -- |
| 🌾 Fiber | 1.7 g | -- |
| Vitamin C | 7.4 mg | 9% |
| Vitamin B6 | 0.12 mg | 9% |
| Potassium | 146 mg | 4% |
| Quercetin | ~20 mg | -- |
| Prebiotics (FOS) | ~2 g | -- |
* RDA - Recommended Daily Allowance (EU Regulation 1169/2011). Percentages are calculated for an adult. Athletes' needs may be higher.
💪 Benefits for Athletes
Here are the main onions benefits in an athlete's nutrition:
- Quercetin - a strong antioxidant and natural antihistamine
- Prebiotics - nourish good gut bacteria
- Allicin (in chopped onions) - antibacterial properties
- Source of chromium - for improving insulin sensitivity
🍳 How to Prepare
The best ways to prepare onions, while preserving maximum nutritional value:
- Cook: until golden - caramelizes, becomes sweet
- Fresh in salads: chopped red onions
- Base for soups: with carrots, celery - classic mirepoix
⚡ When to Eat?
Anytime as a seasoning. Before training - in moderation due to fiber.
🔄 Substitutions and Alternatives
Best alternatives onions:
Spring onions, leeks, shallots, garlic
💡 Tips
- Chill in the refrigerator for 30 min before chopping - fewer tears
- Red onions have more antioxidants
- Cooked onions have no pungent smell - suitable before going out
- Store in a dark, cool place - not in the refrigerator
🥄 Portions And How To Include In Diet
Onion — the main flavor enhancer, not the “star” of the dish. One medium onion (about 100 g) in a dish provides flavor for few calories. Use it as a base for stews, soups and sauces.
- Sauté until translucent — the base for sauces and soups.
- Raw, chopped — for salads and snacks (milder — red onions).
- Caramelized — a sweet side dish with meat.
🛒 How To Choose And Store
Choose firm onions with dry, papery skin and no soft or rotten spots. Store cool, dark and dry, separate from potatoes — otherwise both spoil faster.
- Whole onions keep for several weeks in a dry place.
- Store chopped onions in the refrigerator in an airtight container — for up to several days.
- Spring onions — in the refrigerator, wrapped in damp paper.
⚠️ Common Mistakes
- Too high heat — onions burn quickly and become bitter.
- Storing with potatoes — both spoil faster.
- Always raw in large amounts — for a sensitive stomach, cooked or baked is better.
📋 What Is Important To Know
The pungency and smell of onions are determined by sulfur compounds that are released when chopping — then an enzyme turns them into volatile irritants that make eyes water. Onions also contain soluble fiber that feeds gut bacteria. Onions are very low in calories, so they are excellent for flavoring a dish without adding energy.
⚖️ Portions And Daily Norm
- 20–40 g (a quarter to half of a medium onion) is enough to flavor a dish.
- Onions are not a main food source — they act as an addition, so there is no “daily norm” for them.
- If your stomach is sensitive, start with heat-treated onions — during cooking the pungent compounds break down.
- Combine raw onions with fats (oil, sour cream) so that some fat-soluble substances are better absorbed.
🙋 Frequently Asked Questions
How to chop without tears? Freeze the onion for half an hour before chopping or chop under running water — cold slows down the enzyme activity.
Are raw onions healthier? They retain more sensitive compounds, but cooked onions are easier to digest; it is practical to use both.
Why does onion smell linger? Sulfur compounds enter the blood and are released with breath; drinking plenty of water and eating parsley helps.