Heat treatment destroys vitamins in vegetables: yes or no?

Image by Leo_65 from Pixabay

Heat treatment changes the composition of fruits and vegetables, but this is not always bad. Several studies have shown that under the influence of temperature, some nutrients are destroyed, but others are released.

It’s all about the type of nutrient.
Many people think that raw vegetables contain more nutrients than cooked vegetables, but it depends on the type of substance.

During heat treatment, the thick cell walls of many plants are destroyed, releasing the nutrients stored in them.

A German study conducted on a group of 200 raw foodists showed that they had higher levels of beta-carotene in plasma, but the lycopene content was below average. One of the factors that influenced the result was a lower lycopene content in raw tomatoes compared to heat-treated.

What happens to vitamin C and other water-soluble substances.
According to a report by researchers from the University of California, Davis, the loss of vitamin C, depending on the method of preparation, can range from 15% to 55%. Fresh spinach loses about ⅔ during cooking, and peas and carrots lose 85–95% of vitamin C.

Water-soluble nutrients, such as vitamin C, vitamin B, and polyphenols, are most prone to degradation during processing and cooking.

Interestingly, the level of vitamin C is often higher in frozen foods compared to fresh ones due to the fact that it decreases during the storage and transportation of raw crops.

Another study found that after six months of freezing, cherries lost 50% of anthocyanins, the nutrients found in the dark pigments of fruits and vegetables. So vitamins are not always stored in frozen foods.

What happens to vitamin A and other fat-soluble substances.
According to a report published in The Journal of Agriculture and Food Chemistry, to preserve vitamins in carrots, zucchini, and broccoli, it’s better to cook them than to steam, fry, or eat raw. Frying turned out to be the worst way to conserve nutrients.

Fat-soluble compounds such as vitamins A, D, E, and K, and antioxidant compounds called carotenoids are better preserved during cooking and heat treatment.

But when it comes to cooking vegetables, you always have to compromise. The same method can increase the availability of some nutrients but decompose others. For example, boiled carrots have higher carotenoid levels compared to raw carrots. However, unprocessed carrots have much more polyphenols, which disappear as soon as you start cooking them.

What happens to vitamins in the microwave.
Although many people think that cooking in a microwave is harmful, vegetables cooked in it may have a higher concentration of certain vitamins.

In March 2007, an experiment was conducted in which scientists observed how boiling, steaming, microwave cooking, and pressure cooking affect nutrients in broccoli. Steaming and boiling led to a loss of 22 to 34% of vitamin C. Cooked in a microwave and under pressure, vegetables retained 90% of vitamin C.


  1. No way to prepare, serve and store food will not retain all the nutrients in vegetables.
  2. If scientists have decided that boiled zucchini is useful, it’s not yet a fact that it will suit you. If he does not go into your throat, then it will not bring any benefit. Therefore, choosing a cooking method, rely also on your taste.
  3. The best way to get the maximum benefit from vegetables is to enjoy them in different variations: raw, stewed, boiled, baked, and grilled.
  4. If you regularly eat a variety of fruits and vegetables, you can not worry about the method of cooking.

15 thoughts on “Heat treatment destroys vitamins in vegetables: yes or no?”

  1. Roasting veggies on the barbeque is pretty delicious. My son-in-law and daughter do a great job and preparing all vegetarian meals. They are super healthy and extremely delicious. I like your post, and wonder what your recipe That you like to use when you barbeque or oven roast vegetables.

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