MadSci Network: General Biology

Re: Does the DNA change when foods are microwaved?

Date: Tue Sep 12 16:34:14 2006
Posted By: Peter Bosani, Independent
Area of science: General Biology
ID: 1157503120.Gb

Hello, Brittany.

Microwave cooking has unjustifiably received a "bad rap."  Many people 
popularly believe that microwaves are radioactive and that eating food 
from microwave ovens will make them "glow in the dark."  To top it off, 
some of the science behind microwaves have been misinterpreted or 
misunderstood by the general population, due to false data, unfounded 
rumours and fears, spread by questionable websites, and even the popular 

Case in point, Spanish researchers microwaved 1-1/2 stalks of broccoli in 
2/3rds cup of water, on high for 5 minutes, and then compared its nutrient 
content to other forms of cooking.  They found a significant loss of 
nutrients in microwaved broccoli compared to boiling or steaming.  Well 
sure, they overcooked it!  To preserve nutrients in microwaved vegetables 
the idea is to use just a little water, (i.e. a couple of tablespoons), 
for as short a time as possible, just enough to tenderize it.  It's well 
known that because microwave ovens cook so fast, they end up preserving 
more nutrients than other forms of cooking, provided of course, that 
they're not overcooked.

Furthermore, microwave cooking does not produce cancer-causing substances 
called (HAA's) - heterocyclic aromatic amines, which are commonly produced 
by frying, grilling, or broiling.

Perhaps your question was prompted by a recent story going round of a 
woman who died, after receiving a blood transfusion that was heated up in 
a microwave oven.  Yes, this is true, but the culprit here was not that 
the microwave somehow changed the blood by breaking its DNA, or creating 
some kind of poison.  Once again, it was due to overheating.  Simply put, 
when blood is overheated, it causes the blood cells to break apart.  Red 
blood cells are unstable at temperatures over 49C.  This can lead to 
serious side effects and can even be fatal when undergoing blood 
transfusions.  Safer methods of heating blood for transfusions are usually 
employed by technicians, that enable better temperature control than with 
microwaves.  However, any type of heating method that results in 
overheated blood could be dangerous, not merely because they're from 
microwave ovens.

Finally, can microwaves or its cooking break apart DNA, and also, does 
microwave cooking cause cancer?  The short answer is no.  Simply put, 
microwaves are a nonionizing form of radiation, which means they cannot 
break apart the nucleus of a cell, they cannot break DNA apart, and there 
is no credible evidence to suggest that it could cause cancer.  This is in 
contrast to ionizing radiation, which can indeed beak apart DNA and cause 
cellular damage.  Examples of these are: x-rays, ultraviolet rays, gamma 
radiaition, and cosmic radiation.  For this reason we are told to minimize 
x-rays, wear protective spacesuits in space, and slather on sunscreen on 

Microwaves are very efficient for satellite and electronic communications, 
as well as cooking.

So don't believe the various scaremongers and microwave alarmists you may 
hear from or come across on the net.  As far as I know, they still have 
not succeeded in changing the laws of physics.

Hope that helps,

Peter Bosani.

References & Further Reading:  Science Matters - R.M. Hazen & J. Trefil - 
Doubleday publishers.
                               Let Them Eat Flax - J. Schwarcz- ECW Press  

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