Vegetables heat treatment: yes or no?

Nowadays, the diet is oversaturated with sweets, refined fats, all kinds of chemical additives, the excessive use of which negatively affects health. An alternative to unhealthy foods is vegetables, which are rich in vitamins, minerals, dietary fiber and phytochemicals. Daily consumption of vegetables can improve gastrointestinal health, reduce the risk of cardiovascular disease, and chronic diseases such as diabetes and some forms of cancer.

The amount of nutrients in the prepared dish can vary depending on the cooking method: raw vegetables have more vitamin C, while thermally processed ones have more vitamins A, D, E and K.

Water soluble and fat soluble vitamins

Vegetables fortified with water-soluble vitamins, especially vitamin C and B, tend to be more sensitive to cooking and prone to nutrient loss. Since the latter are soluble in water, they are washed out of vegetables during cooking. That's why when you boil vegetables or reheat them in the microwave using a lot of water, you get less thiamine, folic acid, vitamin B6, B12, and much less vitamin C. According to a review by researchers at the University of California, Davis, up to 55% of vitamin C contained in vegetables is lost during heat treatment.

The polyphenols (phytochemicals) found in kale, spinach, and broccoli are also susceptible to degradation during cooking.

Fat-soluble compounds such as vitamins A, D, E, and K, as well as antioxidant compounds called carotenoids, are more stable and arenbetter preserved during cooking. A study published in ACS Publications demonstrated that boiled carrots, zucchini and broccoli are more nutritious when cooked. That is, boiled carrots significantly increase measurable levels of carotenoids compared to raw carrots. And at the same time, raw carrots contain much more polyphenols, which disappear during heat treatment.

Benefits of eating boiled vegetables:

•  Cholesterol under control

Boiling is a great way to cook food and keep excess oils out. Many vegetables already contain natural oils, so additional cooking oil is not recommended for those who need to watch their cholesterol levels.

•  Reduces stomach inflammation

The heat treatment of vegetables destroys most of the microorganisms, which makes food safer. Also, boiled vegetables are easier to digest, which accordingly requires less production of gastric juice, and this makes it possible to avoid increased acidity of the stomach.

•  Helps with kidney stones

Kidney stones are partly formed due to oxalates, a salt of oxalic acid. Boiling vegetables helps to get rid of 87% of oxalates, thereby reducing their amount when consumed with food.

•  Beneficial effect on the skin.

Increasing your intake of fruits and vegetables, especially those that are high in fiber, water, and antioxidants, can help keep your skin healthy, as these qualities are retained in vegetables after they have been cooked.

Baked and fried vegetables

This is a great way to cook vegetables! The main thing is not to overcook them. Aas soon as the vegetables begin to lose their texture and brightness, they have begun to lose their antioxidant capacity. Therefore, grilled vegetables with a little oil can acquire not only a rich taste, but are also very healthy. Especially, try to opt for:

•  green beans;
•  asparagus;
•  broccoli;
•  celery;
•  spinach;
•  tomatoes;
•  eggplant and onion.

All these products retain their antioxidant activity after heat treatment.

A study published in the National Library of Medicine found that cooking tomatoes produces more lycopene (a fat-soluble red pigment found primarily in tomato skins and seeds that has the highest antioxidant activity of any carotenoids), which in turn may reduce the risk of a range of diseases, from Alzheimer's disease to cancer.

Things to keep in mind when preparing vegetables:

•  always wash vegetables before cooking to limit nutrient loss;
•  cut vegetables into large and uniform pieces to avoid loss of nutrients during cooking;
•  add a limited amount of water when cooking vegetables, as excess water can leach out water-soluble vitamins;
•  sprinkle some salt into boiling water to enhance the taste of vegetables.

Freezing vegetables

An interesting fact is that frozen vegetables may actually contain more nutrients than fresh vegetables, because as products mature and age during the sorting process, from the fields to the grocery store and then to the kitchen table, they lose some of their nutrients.

Frozen vegetables closely match the nutritional content of their freshly harvested counterparts because they are flash-frozen at their peak of ripeness, which is when they are most nutrient dense. Fruits that go to the vegetable section of grocery stores are usually harvested before they are ripe, giving them less time to reach their full nutritional potential.

Vegetables are a very important part of our diet – they provide the body with nutrients and antioxidants. No cooking method can retain 100% of the nutrients and protective phytochemicals in vegetables. But no matter what cooking method you choose, vegetables in any form are a storehouse of vitamins and minerals.