Do foods heated in the microwave lose nutrients?

The myth that microwaved foods lose more nutrients is one of the most popular in our culture, and many people avoid its use due to this urban legend that has little scientific basis.

To better understand what we are talking about, the first thing to know is how a microwave oven works. Heat is a transfer of energy at the molecular level that results from an increase in the movement of the molecules of a substance. In other words: to heat any food, what is needed is to vibrate its molecules, and due to the resulting friction its temperature rises.

When heated in a frying pan or in a conventional oven, the heat is transmitted to the outside of the food, and the inside will be cooked when that heat is transferred from outside into. However, with the microwave all the food is heated at the same time, and for this the microwave waves are used, which make the water and other polar molecules of the food vibrate in unison.

In short, from a physical point of view there are no great differences in the way of heating food. As Luis Jiménez, a chemist and scientific disseminator, explains: "A microwave increases the temperature by vibrating the polar molecules with microwave radiation, and a conventional oven does it more 'at the beast', generating a lot of heat in some resistances that after transmitting by proximity and infrared radiation. In fact, it is easier to reach very high temperatures in a conventional oven, which could be a risk factor to destroy certain nutrients. "

There are numerous scientific articles that have compared the nutritional quality of heated foods with different methods and show that there is no problem in using the microwave oven. A review published in 1982 in the journal C R C Critical Reviews in Food Science and Nutrition analyzed all existing literature in this regard concluding that there are no significant differences between conventional methods and the microwave.

Any cooking method causes nutrients to be lost

"The destruction of nutrients has more to do with the amount of water used for cooking and the temperature reached in cooking," explains Marian Alonso-Cortés, dietitian-nutritionist and head of training in Aizea. "And, precisely, in the microwave there are those factors in which we can reduce the loss of nutrients, especially vitamins and minerals, because generally little water is used, it is the water itself that cooks it."

For example, a study published in 2009 in the Journal of Food Science found higher levels of antioxidants in some microwaved foods such as onions and asparagus. In fact, this method could be compared to steam cooking, one of the most respectful of the nutritional quality of food.

In short, and as the nutritionist reminds us, "any mode of preparation that involves submerging the food in water or heating it will cause a loss of nutrients. For example, vitamin C or proteins undergo a process of denaturation and transform, but this happens with any method. "

So, if you want to preserve the quality of a whole food, you should eat it raw, but if you want to cook it, you can use the microwave without any kind of repairs.