​Nutrition and microwave cooking

Tuesday 08 May 2018

This week we will look at Microwaves as we continue our theme of cooking methods. Most people have a microwave these days because they are so convenient and energy efficient compared with a conventional oven. It is so easy to pop something in the microwave when we are in a hurry or have very little energy. Most of us know how that feels.

I think it would be interesting to understand how microwaves work first before we look at their suitability as a cooking method or not. The way they work is all quite technical, talking about electromagnetic energy waves and electrical fields. Basically all microwaves have a magnetron which sends microwaves through the food. The waves vibrate the water molecules in the food at thousands of times a second which creates friction. It is the friction that heats up the food.

So what about their safety?
As always there are many arguments for and against the use of microwaves. Some scientists suggest that the radiation energy, can cause damage to the structure of the food molecules, tearing them apart and causing the food to deform which obviously affects the foods quality. Microwaving also causes a change in the taste and texture of the food. The scientific name for this change is ‘structural isomerism’!!!

Others argue that any cooking method can damage the structure of the food not just microwaves. According to Cancer Research UK modern microwaves in good condition are perfectly safe to use because the type of radiation emitted is non ionizing which has enough energy to move things around inside the cell but not enough to change the cell chemically.

Others argue that this is all well and good but it is the accumulative effect of radiation in our homes generally that has not been tested i.e. cell phones, computers as well as microwaves.

An interesting study by a Swiss scientist showed that people who ate microwaved foods regularly had a change in their blood composition. Haemoglobin levels decreased and overall white cell levels and cholesterol levels increased. Also Leukocytes increased (white cells of the immune system), which is often a sign that there is cell damage occurring. This research has been quoted many times and seems to carry quite a powerful message.

In Patrick Holford’s Book, ‘Say No To Cancer’, he recommends that you stand 10ft away from your microwave when it is running to prevent any fallout from the radiation waves. This is despite the fact that manufacturers of modern microwaves do say that if the seal on the door is good there should no exposure.

Studies have looked at the possible link between microwave ovens and cancer. Some results suggest that there may be a link but other studies haven’t been able to prove this at all. Microwaves do produce a magnetic field when they are in use. This drops sharply the further you are away from the microwave and does not last long.

Many experts say that microwave ovens do not give off enough energy to damage the genetic material (DNA) in cells so they cannot cause cancer. Others argue that the DNA is damaged.

As far as nutritional changes all cooking methods will alter the nutritional value of the food.

One argument is that because microwaves use no or little water then the nutritional value seems to be more preserved than when cooking by boiling the food in water and the water then drained away. Thinking outside the microwave box for a minute, as we said last week the moist methods of cooking tend to be the best for meats and fish cookery. For fruits and vegetables I would try and adopt steaming as a method of cooking as this has been shown to be the best way to preserve the valuable vitamins and antioxidants in the food. Having said that I am a huge fan of casseroles, stews and soups because all the liquid that the food is cooked in is eaten so any vitamins that have leached into the liquid are consumed.

One quite important point that I must make is about the use of microwave ready meals that seem very tempting to use. These meals generally come in plastic trays. When plastic is heated it releases the chemical bisphenol A (BPA) which migrates into the food. BPA is potentially carcinogenic. It can disrupt hormone signals, they generally have an oestrogenic effect which is associated with an increase in hormone related cancers and a decline in fertility. The answer would be to transfer the food to a glass or ceramic container before heating.

So what’s the bottom line?
What makes you think that I am going around in circles here!. I think it is a strong case for common sense to prevail. It is very difficult to ignore that fact that microwave ovens are convenient and quick but also we cannot ignore the fact that scientists cannot come to a uniform conclusion about their safety. So like all ambiguous data I would air on the side of caution and if I had a microwave would use it occasionally to perhaps defrost some bread or warm up some baked beans etc. but would try and adopt more conventional methods to cook my main meals. That way the flavour and texture of the food is retained and we would be avoiding any potential hazard that the microwave may have.

This has been a particularly difficult blog to write simply because the evidence available is sparse and very mixed. As a naturopath I am a strong believer that the food we eat should be as close to natural as possible. That way we can get the maximum nutritional value, can control the texture that we want and our cells, which thrive on natural whole foods, will be able to function efficiently.

I can't help thinking that microwaves are a long way from the ideal but accept that they re convenient.

Blog originally written by Caroline April 2013

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