Cooking veg unlocks even more of their valuable nutritional content, and some actually have to be cooked to be made palatable. Potatoes are the best example of this. What’s more, heating food kills harmful germs and bacteria.
On the other hand, heating also destroys valuable nutrients. This is especially true of vitamins, which are unstable and sensitive to heat. But even they aren't completely destroyed during normal home cooking.
Which vegetables benefit from heating?
Carrots contain large amounts of the phytochemical beta-carotene. This fat-soluble substance is known for its positive effect on the eyes and skin. Cooking in a small amount of fat softens the cell walls of the plant tissue, helping our body to absorb it better. According to a study, carrots that have been sautéed in a splash of olive oil contain 28% more beta-carotene than raw carrots.
Tomatoes also benefit from cooking. They contain an antioxidant called lycopene, reputed to have various properties that are beneficial to health and guard against heart disease. Lycopene is a fat-soluble substance, and is therefore better absorbed in combination with healthy fats. Which makes olive oil and tomatoes, those cornerstones of the Mediterranean diet, the perfect match.
The calcium hidden in spinach only develops its full potential when cooked. Because cooking degrades the oxalic acid that binds the calcium and reduces its absorption.
One study has shown that asparagus contains 16-25% more antioxidants when cooked than in its raw form. Antioxidants protect all the body’s cells from free radicals, like those produced by stress or sunbathing.
Which cooking method preserves the most nutrients?
The three key factors in preparing food correctly are: water, temperature and time. The more water you use, the higher the temperature and the longer the cooking period, the more nutrients will be lost.
Most vitamins are water-soluble. This means that they leach out of the food being cooked into the cooking water, which many of us simply pour away. That’s why steaming is one of the best methods to preserve easily damaged nutrients. This technique requires less water and time, ensuring that as many vitamins and minerals as possible are retained.
The example of vitamin C, the most fragile of vitamins, shows how much nutrient loss can vary depending on the cooking method:
- Steaming: up to 15% loss of nutrients
- Microwave: up to 28% loss of nutrients
- Boiling: up to 50% loss of nutrients
Recipe for 1 portion of delicious tomato sauce to store as a handy antioxidant bomb for combating the stress of everyday life
- 2 cloves of garlic, finely chopped
- 1 onion, finely chopped
- 2 tbsp. olive oil
- 1 tin chopped tomatoes (400g)
- 1 tsp. herbes de Provence
- 1 pack of fresh cherry tomatoes
- 1 tbsp. fresh basil, chopped
- Salt and pepper
- Sauté garlic and onions in olive oil until glassy
- Add tinned tomatoes and herbes de Provence and simmer for 10 minutes
- Add fresh tomatoes and herbs and simmer for another 2-3 minutes
- Season with salt & pepper and pour into a storage glass. The sauce can also be puréed to make it finer, thus destroying even more cell walls and releasing even more lycopene.
The tomato sauce is the ideal accompaniment for a portion of whole-grain pasta, cooked spinach and a bit of ricotta – a fabulous way for the body to absorb the nutrients.