Whenever I share my baby food recipes in which I use my microwave to cook various fruits and vegetables to tenderness, I typically receive negative comments about the effects of microwaving on food. Although every American household owns a microwave, and microwaving has been a cooking practice for decades now. But does microwaving kill nutrients in food?
Nutrients are components in foods such as carbohydrates, fats, proteins and amino acids, vitamins, dietary minerals, water, and oxygen that an organism utilizes to survive and grow. Nutrients are necessary for living things to remain alive, but nutrients alone are not living. Thus, microwaving cannot “kill” nutrients in food.
However, cooking can change or destroy nutrients in food. Boiling, steaming, baking, frying, broiling, and grilling as well as microwaving can destroy vitamins and other nutrients in food. For example, boiling broccoli causes a decrease in glucosinolate, the sulfur-containing compound that may give the vegetable cancer-fighting properties. Cooking in water also causes many foods to lose nutritional value because nutrients and soluble fiber leach into the water. However, in some cases, cooking increases certain nutrients in food. For example, cooking tomatoes substantially raises the levels of beneficial compounds called phytochemicals. Therefore, although cooking foods can destroy nutrients, thinking about cooked foods in terms of nutritional changes provides a better foundation for evaluating the effects of microwaving on nutrients than asking if microwaves kill nutrients.
The best cooking methods for retaining nutrients cook quickly, heat foods for the shortest amount of time, and use as little liquid as possible. In many cases, microwaving meats all three criteria. I personally prefer to use my microwave to make baby food because microwaving is much faster than stovetop boiling. Harder foods like apples and pumpkin cook much quicker in my microwave than on the stove, thus decreasing cooking time. Because of the decreased time in the microwave, I also have to add less water during cooking, which also reduces the loss of nutrients. (When I make baby food, I also use the water in which I cooked the fruits and veggies to make the puree or mash, further minimizing the loss of nutrients.) Thus, in many cases, microwaving food causes the least damage to the nutrients compared to other forms of cooking like boiling.
Additionally, microwaving can decrease the amount of harmful chemicals in some foods. For example, microwave-cooked bacon typically has lower levels of nitrosamines than conventionally cooked bacon. Most nitrosamines are carcinogenic, so lower levels in food is beneficial. Grilled and broiled meat, or heat-processed meat, also contains high levels of advanced glycation endproducts (AGEs), which may cause the development or worsening of many degenerative diseases such as diabetes, Alzheimer’s disease, atherosclerosis, and chronic renal failure.
The bottom line is that cooking food changes the nutritional content, for better or for worse. But microwaves generally do not completely destroy nutrients in food. And, compared to other cooking methods, microwaving can sometimes be nutritionally advantageous.
Avoiding harmful byproducts of heat-processed foods protects against risk of Alzheimer’s disease and diabetes: http://icahn.mssm.edu/about-us/news-and-events/avoiding-harmful-byproducts-of-heat-processed-foods-protects-against-risk-of-alzheimers-disease-and-diabetes
The claim: Microwave ovens kill nutrients in food: http://www.nytimes.com/2006/10/17/health/17real.html?_r=0
Effects of heat processing on nutrients: http://link.springer.com/chapter/10.1007/978-94-011-7030-7_12
Effects of microwave cooking/reheating on nutrients and food systems: a review of recent studies: http://europepmc.org/abstract/med/3894486
Italian chefs knew it all along: Cooking plump red tomatoes boosts disease-fighting, nutritional power, Cornell researchers say: http://www.news.cornell.edu/stories/2002/04/cooking-tomatoes-boosts-disease-fighting-power
Microwave cooking and nutrition: http://www.health.harvard.edu/staying-healthy/microwave-cooking-and-nutrition
Does Microwaving ‘Kill’ Nutrients in Food?: https://commons.wikimedia.org/wiki/File:TW_Panasonic_NN-S215.jpg and https://www.flickr.com/photos/kendallfrancis00/6213136139/ (CC BY-NC 2.0)
Panasonic Microwave: https://commons.wikimedia.org/wiki/File:TW_Panasonic_NN-S215.jpg