The myth that microwave-heated 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 foundation.
To better understand what we are talking about, the first thing is to know how a microwave oven works. Heat is a transfer of energy at the molecular level that results from the increase in the movement of the molecules of a substance. In other words: to heat any food, what is needed is to make its molecules vibrate, and due to the resulting friction its temperature rises.
When heated in a skillet or conventional oven, the heat is transmitted to the outside of the food, and the inside will cook when that heat is transferred from the outside to the inside. However, with the microwave all the food is heated at the same time , and for this 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 major differences in the way food is heated. As Luis Jiménez, chemist and scientific communicator, explains: “ A microwave manages to increase the temperature by making the polar molecules vibrate with microwave radiation , and a conventional oven does it more ‘like the beast’, generating a lot of heat in some resistors that after transmit 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 for destroying certain nutrients ”.
There are numerous scientific articles that have compared the nutritional quality of foods heated with different methods and show that there is no problem in using the microwave oven. A review published in 1982 in the journal CRC Critical Reviews in Food Science and Nutrition analyzed all the existing literature on the matter, concluding that there are no significant differences between conventional and microwave methods.
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 at Aizea. “And, precisely, in the microwave there are those factors in which we can reduce the loss of nutrients , especially vitamins and minerals, because little water is generally used, it is the food’s own water that cooks it.” For example, a study published in 2009 in the Journal Food of Science found higher levels of antioxidants in some microwave-cooked foods such as onions and asparagus. In fact, this method could be compared to steaming, one of the most respectful of the nutritional quality of food.
In short, and as the nutritionist reminds us, “any way of preparation that involves immersing the food in water or heating it will cause a loss of nutrients. For example, vitamin C or proteins undergo a denaturation process and are transformed, 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 qualms.
Advisors: Luis Jiménez, chemist and science communicator, author of the blog What science says to lose weight , Marian Alonso-Cortés, dietician – nutritionist, food technologist and head of the technical department at Aizea , Consultancy in Nutrition and Health.
References:
Cross et al. 1982. The effect of microwaves on nutrient value of foods. CRC Critical Reviews in Food Science and Nutrition. Volume 16 (4)
Jiménez-Monreal et al. 2009. Influence of cooking methods on antioxidant activity of vegetables. J Food Sci. 2009 Apr; 74 (3): H97-H103. doi: 10.1111 / j.1750-3841.2009.01091.x.
