Vitamin C is one of the most fragile vitamins. Water-soluble, heat-sensitive and light-sensitive, it can largely be destroyed before it even reaches your plate. Understanding these losses is essential to optimizing your daily nutritional intake.
1. Vitamin C: an extremely fragile molecule
L-ascorbic acid is an organic molecule that degrades easily under the action of several factors:
- Heat: degradation begins at 60°C and accelerates exponentially
- Oxygen: oxidation destroys vitamin C upon contact with air
- Light: UV rays cause rapid photo-degradation
- Water: being water-soluble, it passes into cooking water
- Metals: copper and iron catalyze its destruction
- Alkaline pH: a basic environment (baking soda) destroys it quickly
2. Losses according to storage method
Even before cooking, food storage leads to significant losses:
| Storage method | Duration | Vitamin C loss |
|---|---|---|
| Vegetables at room temperature | 24 hours | 15 to 25% |
| Vegetables at room temperature | 3 days | 40 to 60% |
| Refrigerator (4°C) | 3 days | 10 to 20% |
| Refrigerator (4°C) | 7 days | 25 to 50% |
| Freezing (-18°C) | 3 months | 20 to 40% |
| Drying / dehydration | — | 50 to 80% |
💡 Practical tip: Consume your fruits and vegetables fresh quickly after purchase, ideally within 24-48 hours. Store them in the refrigerator in airtight bags to minimize losses.
3. Losses according to cooking method
Cooking is the most destructive factor. Losses vary considerably depending on the method:
| Cooking method | Temperature | Vitamin C loss |
|---|---|---|
| Raw / no cooking | — | 0% |
| Steam (short) | 100°C, 5 min | 15 to 25% |
| Steam (long) | 100°C, 20 min | 30 to 45% |
| Boiling water (whole vegetables) | 100°C, 10 min | 40 to 55% |
| Boiling water (cut vegetables) | 100°C, 10 min | 55 to 75% |
| Microwave | Variable | 20 to 30% |
| Deep frying | 170-180°C | 60 to 80% |
| Roasting in oven | 200°C, 30 min | 60 to 85% |
| Pressure cooker | 120°C | 50 to 70% |
4. The effect of cutting and peeling
Cutting fruits and vegetables multiplies the contact surface with air and water, accelerating oxidation and losses in cooking water. The smaller the pieces, the greater the losses.
- Peeling removes the outer layers where vitamin C is often concentrated
- Fine cutting can double losses compared to whole vegetables
- Preparing salads in advance leads to progressive oxidation
5. Cooking water: a nutritional waste
When you cook vegetables in water, vitamin C — being water-soluble — passes into the cooking liquid. Studies from INRAE show that:
- Up to 40% of vitamin C ends up in the cooking water
- This cooking water can be reused for broths, soups or sauces
- Steam cooking avoids this leaching phenomenon
🏆 Optimal cooking method: Short steam cooking (5-8 minutes maximum) is the best compromise between palatability and vitamin C preservation. It limits losses to 15-25% while ensuring satisfactory cooking.
6. Comparison of foods by vitamin C content
For reference, here is the vitamin C content of some common foods in their raw state:
| Food | Vitamin C per 100g | After cooking (estimate) |
|---|---|---|
| Camu-camu (FVC Organic powder) | 12,000 – 20,000 mg | Not applicable (powder) |
| Acerola (FVC Organic powder) | 17,000 – 25,000 mg | Not applicable (powder) |
| Sea Buckthorn (FVC Organic powder) | 2,500 – 4,000 mg | Not applicable (powder) |
| Raw red pepper | 190 mg | 90–110 mg (steamed) |
| Fresh parsley | 130 mg | Not applicable (raw) |
| Raw green pepper | 120 mg | 60–75 mg (steamed) |
| Kiwi | 80 mg | Not applicable (raw) |
| Orange | 50 mg | Not applicable (raw) |
| Lemon | 46 mg | Not applicable (raw) |
| Steamed broccoli | 65 mg (raw) | 45–50 mg (steamed 8 min) |
| Boiled potato | 20 mg (raw) | 8–12 mg (boiled) |
7. Conclusion: why supplementation is often necessary
Given this data, it is clear that the modern diet, particularly with its high-temperature cooking methods and long storage times, often provides far less vitamin C than nutritional composition tables suggest.
The recommended daily intake in France is 110 mg per day (ANSES 2021), but many researchers and doctors consider that higher intakes (500 mg to 2g) are optimal for prevention and health maintenance.
Supplementation in the form of pure vitamin C powder, organic superfruit powders or liposomal capsules guarantees consistent intake, without the vagaries of cooking and storage.