Microwaves: Are They Dangerous?

Microwaves: Are They Dangerous?

I admit; I use a microwave from time to time – to heat up leftovers (no TV dinners for this Dietitian!) and a quick bowl of oatmeal when I’m not around a stove. I’m not proud of it, but why? It’s a little something called microwave guilt. Should I feel guilty? Over 90% of homes in America have a radiation box that is used frequently. Is this actually cause for concern?


Think beyond microwaves for a second and let’s look at cooking with heat in general. Raw foodists would gasp at the thought of subjecting food to any heat over 118 degrees Fahrenheit, the temperature at which nutrients and enzymes are found to begin degradation. Water-soluble nutrients such as vitamin C and numerous phytochemicals are lost. In addition, various enzymes responsible for powerful anti-cancer effects and digestion are also reduced or destroyed.

Cooking food produces changes to the physical and chemical structure, which may alter its physiologic effects. To date, I have not seen any evidence supporting or refuting this occurrence with microwave cooking. However, it's widely supported that with certain meats, heat could also cause chemical changes and produce carcinogens that may increase one’s risk of various forms of cancer.

Overall, any type of cooking (baking, grilling, boiling, microwaving) has been shown to reduce phytochemical components of food, but, on the flip side, it may also enhance a few as we’ve seen with the carotenoids found in tomatoes and carrots. There’s usually a slight 5-15% nutrient loss that occurs with minimal heat and water exposure (though phytochemical reduction is usually greater). But cooking is accompanied by certain changes in food, such as starch breakdown, that could possibly support our health by improving digestibility and easing absorption. It can also enhance flavor, color and aroma.

Four considerations to retain the most nutrition out of your food

1. Method – Certain cooking methods retain more nutrients than others. The worst choices for cooking include submersion in hot water, deep-frying and barbecuing. Steaming has been shown as one of the best cooking methods for maximum nutrient retention and, surprisingly, microwaving is up at the top of the list, too. Microwaves do not modify foods in any way that's more deleterious or harmful than other cooking methods. In fact, some have argued that the faster cooking time may actually preserve more nutrients versus other techniques.

2. Time – The longer a food is exposed to heat, the greater the nutrient loss. An interesting experiment showed that boiling cabbage for 2 minutes resulted in a 56% decrease in glucosinolates, while letting it boil for 8-12 minutes further reduced the amount over 70%. In addition, research found in the Food and Chemical Toxicology journal shows that cooking by steaming, microwaving, and stir-frying did not produce significant losses of glucosinolates, the cancer-fighting component in Brassica vegetables like broccoli, Brussels sprouts, and cauliflower when compared to boiling, which resulted in approximately 90% loss of glucosinolates.

3. Temperature – The higher the temperature, the more nutrients lost. Cooking methods such as barbecuing and deep-frying that reach extreme temperatures come with a nutritional cost. You may think of steam as a high-heat way of cooking, but in comparison to other methods, it’s actually much lower. Water boils at 212 degrees F and turns into steam, while ovens are often set to at least 350 degrees F. Food for thought!

4. Eat RAW – Certain foods such as grains and beans must be cooked or sprouted in order for your body to digest them properly. Animal-based foods like meat, pork, and poultry fall into this category as well. For the other plant-based foods, the addition of heat and water tend to dilute their nutritional power.

...back to the microwave!

In our fast-paced life, we use microwaves for quick heat and on-the-go convenience. So, according to these rules, microwaves offer a reduced time to cook, minimal water and moderate heat, which may be why nutrients are retained more so with microwaving than with other cooking methods. Further studies on microwave technology show that they provide equal or better retention of nutrients when compared to conventional, reheated foods for thiamine (vitamin B1), riboflavin (B2), pyridoxine, folacin, and ascorbic acid (vitamin C).

My take? Switch it up! A nice variety of both raw and cooked, whole organic fruits, vegetables, nuts, seeds, grains, legumes, and beans along with some superfoods create a well-balanced diet filled with a plethora of nutrients and phytochemicals. If opting for cooked veggies, don’t overcook them and use minimal water – steaming is my favorite method! When raw, NutriBlasting can enhance digestibility and absorption.


So we’ve established that nutrients can be retained with microwaving, but what about the harmful radiation?

While I don’t want to dive too deep into the other sources of radiation in our high-tech lifestyle, I would like you to also consider computer monitors, television screens, and cell phones as potential radiation sources. In the United States, these are supposed to be subjected to a certain standard and must not exceed a certain level deemed harmful. But do we really know what level we must reach to be considered harmful? I certainly hope so!

Microwaves are forms of non-ionizing electromagnetic radiation. This means that it cannot directly break up atoms or molecules, therefore it is not thought to damage the DNA of living things the way X and gamma rays do. However, they do cause heating effects and at high energies may pose hazards. Microwave ovens on the market today must operate at or below strict limits set by the federal government.

Microwaves work by exciting water molecules within food, causing them to vibrate and bounce into one another, thus producing heat. As far as we know, there is not enough solid evidence that this produces food that is “toxic” to our body. Less nutritious, yes; harmful, who knows? Insight into any alteration of molecules within microwaved food that may cause internal DNA damage after human consumption is yet to be established.

NEVER Microwave Plastic

Most plastics leach chemicals into your food when microwaved together. Film food wrap (LDPE, or low density polyethylene, displaying a Number 4 recycling symbol), containers with Bisphenol A (BPA, displaying a Number 7), and styrofoam (PS, or polystyrene, displaying a Number 6 recycling symbol) are just a few that have been shown to contaminate nearby food. If you choose to use the microwave, place food in non-plastic food containers like glass, Pyrex and microwave-safe ceramic. Keep in mind, “microwave-safe” is not a regulated term, so buyer beware!

Registered Dietitian

No Avatar

Thank you for your comment! It is pending approval and should be posted shortly.