Fruit and vegetables are essential for a balanced nutrition, thanks to their content of fibre, micronutrients (vitamins, minerals) and bioactive substances (i.e. polyphenols). The five daily portions recommended by WHO are sufficient to improve intestinal transit, prevent obesity, reduce the risk of cardiovascular disease, diabetes or colorectal cancer. (1)
Vitamins, in particular, are essential allies for health. The French consumer magazine ’60 Millions de Consommateurs’ provides eight tips for increasing their presence in the daily diet. (2)
1) Choose fresh fruit and vegetables
The highest nutrient content is concentrated in ripe fruit and freshly picked vegetables. A circumstance available only if you grow your own garden, or buy fruit directly from the farmers.
The general population buy ‘fresh’ at markets and supermarkets, where the produce inevitably arrives a few days after being harvested (with the exception of farmers’ markets).
The speed of consumption compared to the harvest is decisive in the concentration of nutrients. In fact, the products oxidize when in contact with air and light.
‘The green beans, for example, lose about 30% of vitamin C per day at room temperature’, says Catherine Lacrosnière, nutrition expert.
2) Don’t disdain frozen vegetables
A compromise solution is the choice of frozen foods.
‘The time which elapses between harvesting and freezing does not exceed 3-4 hours. Therefore, the vitamins present in fruit and vegetables oxidise little’, explains Marie-Josèphe Amiot-Carlin, director of research in the Human Nutrition department at INRAE.
The blanching is the process preceding freezing, which involves rapidly boiling the vegetables and then immersing them in ice water, can destroy some of the vitamins B9 and C (about half), but once frozen there is almost no loss.
Vitamin E and carotenoids (vitamin A precursors) are instead little influenced by the treatment.
2.1) Do not defrost at room temperature
Antioxidant activity of frozen foods has been shown to be comparable to that of fresh foods. However, it is important not to let them defrost at room temperature.
‘A part of the vitamins would be destroyed due to oxidation, while the other would remain in the water resulting from the dissolution of the crystals’, explains Marie-Josèphe Amiot-Carlin.
The suggestion is to cook the vegetables while still frozen, preferably by steaming, or with very little water to avoid draining them.
3) Preserves, pros and cons
The manufacturing process involves cooking at around 120°C and destroys heat-sensitive vitamins (B,C).
Among the vegetable preserves tomatoes are an exception. Whether chopped or in sauce, canned tomatoes can contain up to four times more lycopene – a powerful antioxidant of the carotenoid family – compared to fresh tomatoes.
An added benefit of preserved vegetables is the better digestibility of the fibers, which are better assimilated by the human body.
Please note: however, to choose products with the least amount of salt, to be checked in the nutritional declaration on the label, to prevent its excessive intake in the daily diet.
4) Vary the colors
Vary the vegetables alternating their colors is very useful to maximize their nutritional benefits.
‘Every color reflects a composition with specific vitamins. Green vegetables, for example, are rich in vitamins K and B9, orange vegetables are rich in carotenoids, precursors of vitamin A, etc..’, explains Marie-Josèphe Amiot-Carlin.
5) Promote steam cooking
Vitamin C and some B vitamins degrade rapidly when exposed to light, air and heat. The best way to preserve them is to consume, where possible, raw fruit and vegetables (i.e. carrots, fennel, etc.). Otherwise, steam cooking is recommended, even in a pressure cooker, which is less invasive than boiling in water, as well as cooking in the oven or in a pan.
‘To minimize the loss of vitamins and other micronutrients, it is better to prepare them a little al dente’, advises Catherine Lacrosnière.
In any case it is advisable to peel and cut vegetables just before eating them, choosing large pieces to limit the oxidation process in the air and preserve their vitamin content.
6) Consume the peel, only if organic
Eating fruits and vegetables with the peel maximizes vitamin absorption. This is often the part where most of the micronutrients are concentrated. The peel of an apple, for example, contains four times more vitamin C than the pulp.
But it is important that the food comes from organic farming, since non-organic foods often have pesticide residues on their surface.
In the absence of organic products that is, in cases of digestive disorders due to insoluble fibers, which could irritate the more sensitive intestines, it is advisable to peel the food with a potato peeler in order to reduce the elimination of the peel to the most superficial layer and retain most of the micronutrients.
7) Cook with oil to better assimilate vitamins
The two main families vitamins are fat-soluble (A, D, E, K) and water-soluble (B and C).
Water-soluble vitamins dissolve in water. It is therefore useful to save the cooking water and reuse it as a base for vegetable broths rich in vitamins and mineral salts.
Fat-soluble vitamins are better assimilated by the body if combined with fats, such as extra virgin olive oil, which also improves the flavour of the food.
‘Provitamins A (carotenoids), as well as vitamins E and K, will concentrate in fats, improving their assimilation by the body. In fact, during digestion, fats are able to overcome the intestinal barrier, making these vitamins available to the body’, explains Catherine Lacrosnière.
8) Don’t overdo it with fruit juices
Among the fruit juices without added sugars offered in supermarkets, it is better to choose orange juice, richer in vitamin C and less sweet than other juices such as grape juice. The quantity of vitamin C, however, varies greatly between the various orange juices, as emerged from our market research. (3)
The best solution remains the fresh juice, just squeezed, not subjected to pasteurization which reduces the vitamin content. Without neglecting in any case the sugar content, since three squeezed oranges contain the equivalent of three sugar cubes.
What are the main vitamins for and where can they be found?
Vitamin A is essential for vision, strengthens the immune system and improves skin and hair health. It is produced from carotenoids found in carrots, pumpkins, sweet potatoes, tomatoes, spinach, broccoli, apricots, melons, mangoes.
Vitamin C protects our cells from aging, prevents inflammation, strengthens the immune system and improves the assimilation of iron. They are found in kiwi, blackcurrant, guava, fresh parsley, cabbage, peppers, broccoli, strawberries, oranges.
Vitamin K plays a key role in blood clotting and bone health. It is present in good quantities in cabbage, broccoli, salads, raw spinach, endive, asparagus, kiwi, rhubarb, avocado.
Vitamin E is an antioxidant and protects our cells. Green vegetables, blackberries and broccoli, fresh extra virgin olive oil are a good source.
Vitamin B9(folic acid) prevents malformations of the embryo during pregnancy, growth and cell renewal. Its requirement can be met by consuming spinach, watercress, chicory, valerian, lettuce, endive, leeks, green beans, peas, radishes, asparagus, courgettes, avocado, carrots, melon, citrus fruits, bananas, kiwi, red fruits.
Marta Strinati
Footnotes
(1) World Health Organization suggests a daily intake of 400 g of fruit or vegetables, equivalent to five 80-gram portions. See WHO. Healthy Diet. https://www.who.int/news-room/fact-sheets/detail/healthy-diet
(2) Gautier Cariou. 8 tips to get enough vitamins in your home. 60 Millions de Consumers. 19.8.24 https://www.60millions-mag.com/2024/08/19/8-conseils-pour-faire-le-plein-de-vitamines-dans-votre-assiette-23194
(3) Marta Strinati. Orange-based juices, juices and drinks. 50 in comparison. GIFT (Great Italian Food Trade).
Professional journalist since January 1995, he has worked for newspapers (Il Messaggero, Paese Sera, La Stampa) and periodicals (NumeroUno, Il Salvagente). She is the author of journalistic surveys on food, she has published the book "Reading labels to know what we eat".
