Is it dangerous to heat food in a microwave or just a myth? This topic is still trending after decades of microwave usage. Microwave appliances are present in almost every household today and are being used for cooking, heating, baking etc. It has become a necessity rather than a status symbol, especially in homes where both the partners are working. A microwave is an electric oven that heats and cooks food by exposing it to electromagnetic radiation in the microwave frequency range. Professionals usually prefer stovetop or conventional ovens for cooking, as they believe that dishes do not get the right flavours by other cooking methods. In Indian homes, microwave ovens are often an easy and non-messy way of reheating food, boiling water, or even steaming idly, dhokla or vegetables. Our traditional cooking method and microwave don’t really go together.
The debate around cooking in the microwave actually goes beyond taste-it is about radiation entering the food (and hence our body), it is about the destruction of nutrients in the food, and definitely about the plastic containers and how their chemicals seep into our food causing tremendous long term harm to our body.
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The best way to ensure that we get the maximum nutrition from our food is to buy fresh and locally grown food. Nutrients can be lost by adopting wrong washing techniques, so if you wash your vegetables after cutting, you will lose water-soluble vitamins. Cooking for long periods of time or at high temperature also destroy nutrients. Roasting meat (conventionally) leads to the production of dangerous nitrosamines- in the brown/burnt part- which are associated with several health problems.
Microwave cooking also influences the nutrients. Vitamin B12 is lost in microwave cooking by becoming inactive due to heat, and the temperature in the MVO may go very high-the only plus point is that microwave cooking needs a little lesser time so some nutrients may be saved.
Another water-soluble vitamin – Folate – is lost when green leafy vegetables are boiled in water but cooking in MVO helps prevent this loss to up to 77%. In Indian homes, the loss is mostly because all greens are chopped before washing but cooking is mostly a stir fry or steaming without blanching. Whereas meats cooked in MVO (microwave) have much lower nitrosamine levels because they usually don’t get brown in a microwave.
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Plastic contains a chemical called Phthalates, which seeps into the food when plastic containers are heated in microwaves. This is added to make plastic more flexible and is commonly found in takeaway containers, plastic bottles and plastic wrapping sheets. These are harmful for our body. Studies have shown that these compounds could disrupt our hormones and metabolic system increasing the risk of CHD, insulin resistance, infertility, and asthma among others. However, scientists haven’t really been able to define the level of ingestion where it gets poisonous. Another chemical commonly heard of in this context is Bisphenol (BPA), which has similar reactions in the body.
While heating food, it is advisable to transfer it onto a ceramic bowl or plate, or a glass container to stay safe. If you must use plastic, choose one which clearly says microwave safe.
Temperatures in the food cooked in a microwave oven have been found to be unevenly distributed. Some parts of the food may be cooked while others would still be undercooked or raw. This increases the risk of foodborne bacteria entering our body. Ideally, it is advisable to let the food sit for some time after cooking so that the heat can seep through the entire dish evenly.
No food cooked in a microwave oven is radiation positive. The WHO has stated that food cooked in MVO is safe to consume. The microwave energy goes off the moment the oven is switched off. Also, the chance of getting exposed to microwaves while standing near an MVO is next to impossible as the design ensures no leakage.
Microwave ovens are a convenience and should be used as and when required. Personally, I find cooking in MVO to produce food not as tasty as a stove or normal oven. Indian food – which needs a little more time for flavours to seep the dis – doesn’t work well with MVO. Overall it is safe to use Microwave ovens, just choose the right cooking utensil.
About Rupali DattaRupali Datta is a Clinical Nutritionist and has worked in leading corporate hospitals. She has created and lead teams of professionals to deliver clinical solutions for patients across all medical specialties including critical care. She is a member of the Indian Dietetic Association and Indian Association of Parenteral and Enteral Nutrition.