As a science based fitness and nutrition blog, we get a lot of questions about what research has to say about cooking methods and often times people carry a perception that microwave cooking is not “natural” and causes damage at a “micro” level. So today from a neutral standpoint, we analyze what research studies and health authorities have published on microwave cooking and if we should really avoid it. Here we go:
How It All Began
Microwave ovens became quite popular in western households in 60′s and 70′s because it was quicker and easier than conventional methods of cooking. However, in early 80′s, a couple of Swiss scientists, Hertel and Bernard Blanc did some experiments and found correlations between microwave cooked food and people with low hemoglobin levels, increased white blood cell count and elevated cholesterol levels (all bad stuff, in case you don’t know).
Those experiments were never published in any journal and hence the validity of their claims remains highly controversial but media picked up on it and people started making claims that microwave cooking was not safe. This was the same time when the unfortunate Chernobyl incident occurred and many were scared of any radiation technology being used in that era.
The Fallout from Fear
In principle, physicists and food scientists knew that the radiation emitted by microwaves was non-ionizing unlike that of a nuclear fallout or a radioactive substance and hence should not be very different from conventional cooking methods (traditional cooking includes open exposure to infrared and visible range radiation which are also non-ionizing types of radiation). You can read more about different types of radiation here on US Environmental Protection Agency’s website.
But since it was something common households were exposed to, on a daily basis, in the upcoming years many studies, including that funded by food regulatory authorities like FDA from US, took place and which shaped our current knowledge about microwaves and how it affects our food and us.
Research around Myths on Microwaves
If you don’t want to spiral inwards in the studies, here’s a simpler write-up from WHO which provides direct guidelines on microwave cooking and states that it is completely safe for cooking purposes. For those of you who want more proof to shut up your “fitness freak” friends or some self proclaimed “holistic health gurus”, following are some links which give us a fair idea and a direct comparison on nutrient retention in microwave cooking vis–à–vis conventional cooking methods:
- Critical review done as early as 1982 on American studies on nutrient retention in foods
- Another review of studies in 1989
- Effect on flavonoids in vegetables from microwave cooking similar to normal cooking methods
- Decrease in pollutant bioaccessibility (Cadmium in this case) through microwave cooking
Even now, many health gurus claim that there are nutrient losses when you microwave your food. Well, nutrient losses occur whenever and however you heat food and that depends on heating temperature, cooking time, oil used, frying/stirring techniques and so on. This is not something peculiar to microwave cooking. The longer you cook, the more nutrients you use (as shown in this study on Broccoli nutrient losses).
In addition to it, many claim microwave cooking to be carcinogenic (causing cancer). Here’s a link to Cancer Research UK (Registered Charity which funds cancer research) piece on busting claims of microwave usage being linked to cancer.
- Plastics, a commonly used utensil for microwave cooking, can interact with microwaves (plastics interact with any heated material for that matter) and may not be safe. There are plastic utensils which are especially designed for microwave cooking. Check out Harvard Med’s blog on this specifically to know more on this topic. Considering looser regulatory framework in India and our “go cheap” buying habits, using plastics made in India/China (even claiming to be microwave safe) may not be the best idea.
- Oils tend to oxidize in any heating process, and microwave cooking is not different but since the heating in microwave is intense, this may lead to more oxidation, if cooked for a similar time. There is a lot of interesting food science research going on to improve oxidative stability of oils for microwave usage. To delve deeper into that, check these studies out on Rice bran oil, Canola oil and Sunflower oil.
- In an Indian study, Iodine losses were also found greater in microwave cooking as compared to frying but lesser as compared to pressure cooking. Although as a best practice, salt (primary source of iodine) should be added after your main cooking process for retention of iodine anyway.
Microwave cooking is safe while keeping in mind some exceptions which are listed above. Also, from a nutritional point, it can help a lot in fat loss since it cuts out unnecessary oils needed for cooking in other conventional cooking processes. Also, for working population, microwave cooking is time efficient and a more convenient process which can promote a practice of eating home cooked food instead of ordering their daily meals from outside. What would you choose for your health? A microwave baked/boiled home cooked meal or a spicy junk meal made probably in an big oil pan full of completely oxidated vegetable oil. It’s your choice, after all.
In Lucem Scientiam