ACCORDING TO WHO, IN ONE YEAR ALONE, IN 2013, approximately 5.2 million people died from diseases that could be prevented by regularly eating enough vegetables and fruits. We are talking about non-communicable diseases, primarily oncological and cardiovascular diseases. The organization recommends that adults consume 400 grams of fruits and vegetables a day, and this amount does not include potatoes and other starchy root vegetables. The fiber and water in vegetables help the intestines to function properly; of course, juicy bright vegetables and greens are also an excellent source of vitamins and minerals.
Many people ask questions about the proper storage and preparation of vegetables: do vitamins remain in place after cooking? Does the harm of nitrates negate the benefits of fiber? Is it better to peel vegetables or eat them with the skin? We figure it out together with experts: Candidate of Medical Sciences, nutritionist and founder of healthy food company SOLO Margarita Koroleva, therapist of the mobile clinic DOC + Elvira Ter-Oganesyants and Candidate of Medical Sciences, doctor of sports medicine, nutritionist of the federal network of X-Fit fitness clubs Oleg Iryshkin.
Cooling and freezing
To keep vegetables from spoiling for longer , manufacturers and retailers try to keep them at a low temperature or use shock freezing. Potatoes, cabbage, carrots, beets are well stored in a cool, dry, dark place, for example, in a grocery store. True, the loss of some vitamins is inevitable, and it is unlikely that it will be possible to influence this – few people are ready to regularly dig up a couple of fresh potatoes for dinner. One can only hope for the observance of the temperature and light conditions, in case of violation of which vitamins are lost even faster.
More fragile vegetables – broccoli, cauliflower, green peas, corn, green beans – are kept fresh by shock freezing, during which the food is very quickly cooled to about twenty degrees below zero. This method allows you to preserve not only the taste, but also a large amount of useful microelements. The main thing here is to prevent thawing and re-freezing. It is not difficult to understand how frozen vegetables were stored: if there were no violations, there will be no ice inside the package , and the vegetables themselves will be covered with a light layer of frost.
Clay, film and paraffin
Processing is another option to extend the shelf life of foods. For this purpose, the carrots are coated with clay, soaked in a solution of chalk or treated with antiseptics, and the cucumbers are covered with a mixture of minerals and packed in polyethylene. Tomatoes, eggplants and bell peppers are treated with paraffin and sorbic acid, a natural preservative found in rowan berries. Vegetables processed with these products are glossy, shiny, but these preservatives will not harm the body – this requires a very large amount of them.
According to physician Elvira Ter-Oganesyants, diphenyl (E230) is the most harmful chemical used to process fresh vegetables. This food preservative slows down the appearance of mold and bacteria – but there is evidence that it is associated with the development of various types of allergies and even malignant tumors. In Australia, the use of biphenyl is prohibited , in the United States they urge to treat it with caution, and in Europe it is freely used. With regard to a substance with a similar name – diphenylamine – the policy is reversed: it is banned in Europe, but used in America, where it is not recognized as dangerous. It is believed that the US FDA’s conclusions about the low degree of risk are associated only with poor quality research, and those who want to avoid the accumulation of toxic components in the body are advised to switch to more expensive but safe organic fruits.
Nitrates, nitrites and nitrosamines
Nitrates are salts of nitric acid that are used to fertilize the earth to grow rich crops. These substances can accumulate not only in the soil, but also in plants grown in it and their fruits. In the course of digestion nitrates decompose to safe nitrogen oxide and nitrites, which in turn are converted to nitrosamines – toxic compounds in large quantities harmful, especially for the kidneys and liver. True, not everything is so scary: the body copes well with nitrites and even synthesizes them itself . The question is in quantity: you can safely eat 5 milligrams of nitrates per kilogram of body weight per day ; that is, a person weighing 60 kg can eat up to 300 mg of nitrates – this is a whole kilogram of tomatoes.
True, some vegetables accumulate more nitrates – the leaders are beets, radishes, cabbage salads and celery. In addition, these substances accumulate unevenly: in cabbage, they are most in the stalk, in carrots – in the core, in cucumbers – in the “bottom”, and in leafy vegetables (greens) – in the stems. You can reduce the amount of nitrates in vegetables by heat treatment (however, there will be less benefits from boiled, stewed and baked fruits), as well as by removing the peel or stalks of greens. Lemon juice contributes to the breakdown of nitrates , so it makes sense to add it to vegetable salads. There is an opinion that you can get rid of nitrates by soaking vegetables in cold water or adding potatoes to the dish, which “absorb” these substances – but at the same time, “giving” a small part of nitrates to water or potatoes, vegetables will also lose useful potassium and calcium salts.
Water and brush
Particles of soil and dust, contaminated with pathogenic bacteria and parasite eggs, as well as harmful chemical compounds, can remain on vegetables , so they must be washed . The pesticides used to treat the kidney also often get on the fruit. The closer the vegetable grew to the ground, the more thoroughly it needs to be washed – if it is enough to rinse the tomatoes with warm running water, then it is better to rub the radishes and carrots with a sponge or brush.
There are also special detergents for vegetables and fruits designed to wash away pesticides, dirt and wax. While their use can be reassuring (it’s nice to know that you are doing something useful for yourself), the official sources of the recommendations consider it overkill. According to research , ordinary water coped with cleansing products as well or better than special products. It is recommended to wash vegetables shortly before use. If you want to dry them, use a clean towel or paper towel. If you bought a package with washed vegetables or herbs, you do not need to rewash them .
Storage and peel
It is best to store root vegetables in a cool and dry place – in the closet, on the balcony (not in summer), or in a regular kitchen cabinet. It is enough to keep cabbage, tomatoes, cucumbers, eggplants, bell peppers, celery in the refrigerator, in the vegetable compartment. Do not store plant products in the light: under the influence of ultraviolet radiation, they lose some of the nutrients , including vitamins B2 and K, so it is better not to put the basket with apples on the windowsill. Greens do not tolerate long-term storage and quickly lose their beneficial properties. Before storing it, it is recommended to rinse it, cut the roots (if any), dry it and wrap it in a paper towel or put it in a bag.
According to nutritionist Margarita Koroleva, the concentration of vitamins and microelements in the peel of many fruits is the highest – but toxic substances accumulate in it. For example, nitrates accumulate in the peel of a cucumber, but at the same time it contains a lot of vitamins C, B1, B2, biotin and carotene, as well as calcium, potassium and magnesium. It turns out that farmed, unprocessed vegetables are best eaten with the skin. If you are peeling vegetables – for health reasons or simply for taste – they still need to be washed first. Otherwise, dirt from the peel may get onto the fruit pulp during peeling.
Cooking, frying and salads
Fresh vegetables tend to be more beneficial, but there are exceptions. For example, cruciferous vegetables (broccoli and other types of cabbage) raw due to their high fiber content can cause bloating and flatulence. Moreover, the longer the heat treatment and the higher the temperature, the less nutrients the products retain. Spinach loses about 60% of vitamins during cooking , and carrots – up to 95%, so it is better to eat them raw. On the other hand, to get the same amount of lycopene, an important antioxidant in tomatoes, you need to eat fewer cooked vegetables than raw vegetables (and most of it is found in tomato paste ).
It is important not to cook vegetables for too long. When cooked al dente, green beans, asparagus, beets, zucchini, broccoli, cauliflower will be slightly harsh and crispy – and retain enough vitamins, minerals and fiber. Of course, it is important to consider your own tastes: if you like soup or pasta sauce with boiled, soft pieces of vegetables, you should not deny yourself. It is better to cut vegetables right before eating or cooking – otherwise, many substances, including vitamin C, will have time to oxidize in the air.
Glucose and starch
The glycemic index of most vegetables increases during the cooking process – that is, the longer the food is cooked or fried, the faster the sugar is absorbed from it. This is due to the partial breakdown of complex carbohydrates – they become more available for digestion. For example, the glycemic index of fresh zucchini is 15, and fried – already 75. Jumps in glucose levels are undesirable primarily for people with diabetes mellitus or its risk. To avoid unpleasant consequences, vegetables should be eaten raw or lightly processed, but crispy. It is best to cook them for a few minutes in a small amount of water and always over high heat – so their glycemic index will increase slightly and the products will not leave too many useful substances in the water.
Sometimes you can hear about the dangers of foods that contribute to the formation of mucus in the intestines – and even about the need to “cleanse” the body of mucus. But this is the same legend as the “detox from toxins” necessary for everyone. In fact, many grains, fruits and vegetables, such as oats, rice, flaxseeds, bananas, pumpkin, and potatoes, contain a special type of carbohydrate (heteropolysaccharide) that has gelling properties. Once in the intestines, fragments of such food soften and increase in volume due to the resulting mucus – like the use of fiber, this contributes to the full functioning of the intestines. According to nutritionist Oleg Iryshkin, when choosing products, different characteristics should be weighed: the same potato is useful for the digestive system as a mucus-forming product, but in combination with other components of a particular person’s diet, it may contain too many carbohydrates or calories