Is it safe to cook food in a microwave?

The microwave has long been known as the “king of convenience” in the modern kitchen. Just put in last night’s leftovers, press the button for a few minutes and you have a hot meal, saving time and still delicious.

However, despite their popularity, microwaves are often the center of controversy. Some argue that using microwaves can reduce the nutritional value of food and even pose a potential health risk. These concerns have led many to question the safety of these devices.

However, according to experts and reputable health organizations, microwave ovens are completely safe if used properly. Microwave heating technology does not make food “radioactive” or “toxic” as many people mistakenly believe.

So, what has caused microwaves to be misunderstood all this time, and why can you safely use them in your everyday cooking?

Understanding "radiation" from microwave ovens

Before 5G conspiracy theories took center stage, microwaves were the “number one suspect” in conversations around the word “radiation.” Some feared that the devices could contaminate food with radiation.

But the fact is, unless you intentionally pop yourself into the microwave with dinner, the energy the appliance uses is completely harmless and cannot make food radioactive.

Microwave ovens work by emitting microwaves, a form of electromagnetic radiation with frequencies similar to radio or radar waves, which is completely different from dangerous ionizing radiation such as X-rays or nuclear radiation.

Additionally, modern microwave ovens are designed with metal casings and protective shields to keep the energy inside. As long as the appliance is not severely damaged, the amount of microwave leakage to the outside is extremely low, almost negligible.

According to the World Health Organization (WHO), in the rare event of a leak, the energy released would have to be extremely high and prolonged exposure would be required to cause thermal injury, which is unlikely under normal use.

Therefore, the fear of radiation from microwave ovens is largely based on misunderstanding. When used properly and maintained properly, microwave ovens are completely safe for the health of users.

Microwaves and Bacteria: Understanding for Safe Cooking

One of the common concerns about microwave cooking is its ability to kill harmful bacteria in food. Many people worry that microwaves do not heat deeply enough or long enough, which could lead to bacteria surviving and causing food poisoning. However, the danger lies not in the technology but in how it is used.

Unlike traditional ovens, microwaves heat food using electromagnetic waves, causing the water molecules in the food to vibrate and generate heat. The problem is that this process is sometimes uneven, resulting in parts of the food not reaching a safe temperature even though it appears to be boiling or steaming on the outside.

To fix this, users need to take a few simple but important steps. First, follow cooking instructions if available, especially for frozen or processed foods.

During the heating process, stir, rotate or flip the food at least once to distribute the heat more evenly. Additionally, using a food thermometer is the most effective way to ensure that the core of the food reaches a minimum temperature of 75°C, which can kill most disease-causing microorganisms.

Finally, don’t skip the “let it sit” step after removing the food from the oven. This is the time for the heat to continue to spread inside the food, helping to complete the cooking process and increase the effectiveness of the sterilization. When used properly, the microwave can be a completely safe, economical and effective cooking tool.

Microwaves and Nutrition: The Truth Behind the Myths

A common misconception is that microwaving food will “lose nutrients” and reduce its nutritional value. However, the reality is that any cooking method, whether steaming, boiling, frying, or baking, can reduce some of the heat-sensitive nutrients, such as vitamin C and some antioxidants.

In the case of vegetables, cooking in too much water can lead to even greater nutrient loss, as water-soluble vitamins are washed away in the excess water after cooking. In contrast, microwaves have significant advantages such as short cooking times, low water use, and direct heating of the food, factors that help minimize nutrient degradation.

According to Harvard Health Publishing, a health information channel of Harvard Medical School (USA), the cooking method that best retains nutrients is the method that is fast, uses little liquid and has a short heating time. Microwave ovens meet all of those criteria.

In line with this view, a study published in 2023 in the journal Heliyon (UK) compared three popular cooking methods: microwaving, steaming, and boiling. The results showed that microwaving was the most effective way to preserve the nutritional value of vegetables.

So, if you are concerned about losing nutrients when using a microwave, you can rest assured because this device not only saves time but can also help you retain many valuable nutrients in your daily diet.

Plastic and Microwaves: The Concerns Behind the Convenience

In modern life, many of us are used to using plastic containers to heat food in the microwave, from ready-made meals bought at the supermarket to leftovers stored in the refrigerator.

However, along with the convenience are growing concerns that chemical compounds from plastic can leach into food when heated, potentially causing harm to health.

One of the most talked about groups of chemicals is phthalates, compounds commonly used to soften and increase plastic flexibility. Some studies have shown that phthalates can affect the endocrine system, disrupt hormones, and are even linked to neurological development in young children.

However, the current evidence is not enough to draw firm conclusions, and scientists say more research is needed to determine the specific link between phthalates and human health effects.

In the United States, the use of phthalates in food packaging is monitored by the Food and Drug Administration (FDA). Currently, there are nine phthalates approved by the FDA for use in food contact applications, including microwaveable containers.

The agency says approved materials have undergone extensive safety evaluations. However, the FDA has faced numerous petitions calling for a complete ban on phthalates in food packaging.

These recommendations have so far been rejected due to a lack of convincing scientific evidence. In a statement, the FDA said that phthalate exposure from food is trending down, while also affirming that it continues to closely monitor the latest safety data.

Besides phthalates, another prominent concern is microplastics, tiny plastic particles that are increasingly being detected in the environment, drinking water, and now food.

A recent study has shown that heating a plastic container in the microwave can release millions of microplastic particles and billions of plastic nanoparticles in just a few minutes. Specifically, researchers noted that just one square centimeter of plastic surface can release up to 4.22 million microplastic particles and 2.11 billion plastic nanoparticles after 3 minutes of heating.

Although one study found that these microplastics can kill human kidney cells in a laboratory setting, experts note that the results cannot be directly applied to living humans because the difference between experimental conditions and the actual physiological environment is very large.

While there’s no clear reason to throw away all plastic containers, if you’re concerned, you can always opt for a safer option, such as transferring food to a microwave-safe glass or ceramic container before heating it. While it may take a few extra minutes to wash dishes, you’ll be more confident in your long-term health.

Things to avoid when using a microwave

Microwaves are convenient, but if used incorrectly, they can be a health and safety hazard. One of the most important rules is to avoid using metal, including aluminum foil, stainless steel containers, or any other material that contains metal. These substances can cause arcing, sparks, and even fires.

Some foods, such as eggs in their shells, whole potatoes, or sausages, can explode if heated directly without venting. To avoid kitchen accidents, cut, puncture, or peel the shell before placing in the oven.

Microwaves also have the disadvantage of heating unevenly, which can leave some food uncooked, increasing the risk of bacterial poisoning. Therefore, stir the food thoroughly and check it before serving.

Finally, do not reheat food, especially rice, as bacteria can thrive if not stored and heated properly.