Avatar universal

Does Microwave's kill vitamins?

I keep hearing that eating foods raw is the best way to go and that microwaving vegetables or meat kills most of the nutrients.  Does anyone know if this is true or not?  I haven't been able to find any information regarding this to be the case but I may not be looking in the right place.

22 Responses
144586 tn?1284666164
That is an excellent question, and the answer is "it depends". Microwaves cause a lot of destruction. Radar operaters exposed to the radiation have contracted cararacts. The "it depends" means it depends on the vitamin, the intensity of the exposure and the duration of the exposure. I am providing a "guess", but my feeling is that microwaving destroys more nutrients than conventional cooking. The positive trade-off is that microwaving is also more effective in killing some deady bacteria that conventional cooking won't. You want a ride on the roller coaster or the ferris wheel?
203342 tn?1328737207
Actually, it's the other way around. More vitamins are destroyed by conventional cooking than microwave cooking. Microwaves don't have as high of heat and cooks quicker so therefore less vitamins are destroyed. You can do a google search about it and see more on that subject. Of course, the best way to eat is food that is in it's most natural state or raw. Then of course you have the pesticides to worry about unless you're eating organic. :)
144586 tn?1284666164
Sounds good to me April. As I said, I was providing a guess. I'm always willing to defer to those who know more about a subject. ")
Avatar universal
You're correct April.  I googled it. Looks like cooking with too much water, either microwave or stove top, is the real culprit.  That makes sense for water soluble vitamins.  Some of the articles actually said that nuking a vegetable are better for nutrition.

Guess I should have looked this up before posting a question but I figured someone on here would know off the top of their head.  Thanks again April ;D
Avatar universal
It just doesn't make any logical sense to me that nuking a vegetable keeps it's more nutritional. How can the differing temperatures have anything to do with it? Conventional cooking uses radiated heat, whereas the microwave is using high electromagentic frequencies. This "heat" is absorbed by the food, but what's really happening here?

The heat must be generated by the molecules realigning themselves with the high frequencies (this'll be fairly rapid, let's say millions of adjustments a second), this must also be changing their physical properties in the process.

Will these nutritional molecules be the same after this? I doubt it.... So I'll not bother with the microwave thanks....
Avatar universal
Hmm interesting question.

Theres been a big issue about whether microwaving is good, as lots of
resources claim a variety of things.

Microwaving is fine to reheat your food, however food generally
must not be reheated more than once.
Meat is not very good for reheating, however microwaving retains 98% of

According to the good medicine magazine, it doesnt retain its nutrients when
broccoli is microwaved.  Broccoli is best steamed.

Avatar universal
I'm a physics student, so I will try to explain what I know about microwave energy and subatomics so that you understand why your argument is mistaken.  

The differing temperatures do have something to do with it because the molecular bonds in the vitamins will break down at different temperatures.  To a molecule there is no difference between radiated heat and heat caused by absorbing photons (electromagnetic waves), the end result is the same: the molecule vibrates more quickly.

In actuality the food as a whole does not absorb much heat from the microwaves, only the moisture in the food does.  Microwaves are relatively low-energy lightwaves and don't carry a lot of energy on their own.  However, their frequency is very close to the natural  vibrational frequency of a water molecule.  This causes the water molecules in the food to vibrate very quickly (synonymous with heating up).  The rest of the food heats up only because the water on or inside them heats up.

You are mistaken when you say that... "The heat must be generated by the molecules realigning themselves with the high frequencies".  I'm not too sure what you mean by this, but molecules are not aligning themselves with anything.  Water molecules are heating up by resonating with the microwaves, and everything else heats up by being in contact with the water.  Ever notice that if you turn on a microwave while empty, the air inside doesn't heat up?  That's because the microwaves themselves don't actually carry much energy, it is only because it can raise the temperature of water that it cooks food.

You're correct when you say that "this must also be changing their physical properties in the process", but this is really the whole point of cooking.  It is true even if you cook the food conventionally.  The molecules in the food are vibrating and changing just as they would be if you heated them in a pan or a pot, or over a fire.  Heat is vibration and vibration is heat, no matter the source, and heat energy can drive chemical reactions.

Lastly, many vitamins are water soluble, which means they will dissolve in water.  If the vegetable is immersed in water, for instance when you boil it, the water soluble vitamins will dissolve and leave the vegetable.  Also, if you cook it on high heat, the vitamins will break down due to the heat just as if you microwaved it.  The difference is that the microwave cooks the food in its own water, so that the water soluble vitamins do not leave the vegetable.  They may break down, but this can happen in traditional cooking methods as well.

I hope this has been helpful in understanding the physics and molecular processes that happen with microwaves, and why microwaves aren't evil.  Microwaves are nothing to be scared of, they are a form of light just like red, blue, and green visible light that comes from the sun or a lightbulb.  In fact, microwaves carry less energy per photon than even visible light does, so if you're afraid of a microwave altering the chemical structure of your food, you should be even more afraid of the sun doing it on the way home from the store.
Avatar universal
That is quite an explanation about cooking with a microwave!  Thank you for taking the time to answer my post.
Avatar universal
Thanks for spending the time to write that gawdzilla. My assumptions on the heating process were largely based on my imagination than physics (as you so expertly pointed out ;).

Now please can a biochemist come along and confirm that a microwave's irradiation of our food is not doing anything evil?

My imagination is still running wild on this one... (How I wish I was a biochemist so I could run through some tests and see the results with my own eyes)
498922 tn?1220807116
Microwaves will not destroy food nutrition values, however, raw veggies ARE much healthier, and organic veggies are best.
Avatar universal
I think you may be a bit wrong on one detail. According to the following web site, the heating is not caused by increased vibration of the water molecules but via their increased rotation. What causes this? The water molecules act as tiny magnets ("dipoles") that are flipped by the electromagnetic microwaves, which have just the frequency to do this to the water molecules (but not others). As the water molecules rotate, they bump into other molecules, causing them to increase their linear speed, and this is what  causes heating.

Vibration itself apparently does not contribute to heating.

Avatar universal
I suggest you all read this...http://www.relfe.com/microwave.html

...and then you may reconsider Microwave. I haven't used a Microwave in years and in the last couple of years my mum only used the Microwave to sterilise her sponges in the kitchen before investing in a steam oven...

Avatar universal
I suggest you read what Connie773 linked to and have a good laugh at such quackery sites :-)

Really ridiculous and totally unscientific. Also they had an ad right next to it for ear candles, which basically tells you what kind of site you are on...

Another good example that you shouldn't believe everything you read - just consider the sources and think for yourself, it's not that hard :-)
Avatar universal
I have a microwave in my home. I don't even open the door. Putting foods in it changes the composition of the food and puts off stuff that you don't want in your body or your home.  Cancer rates rose dramatically when microwaves were put in to the home.  Also it was around that time Vitamin D and Iodine were taken out of foods so two great supplements to look in to. I take both.  
Also using plastics to heat food in the microwave, the plastics change when heated and it goes in to your food.  
Foods are best used the day you buy them. I don't eat raw I wish I did more of that. But I buy only fresh vegetables, occasionally frozen.  I always prepare them but don't ever over cook them so they retain some of their vitamins.  
Best to you.
Avatar universal
I see you were interested in a biochemists perspective. As a biochemist I will start by telling you that answers in biochemistry are usually complex. This is no exception. In general microwaves are not evil. As our physics student has pointed out microwave radiation falls between visible light (relatively high energy but still not so bad) and radio waves (like the am and fm waves that bring music to you from great distances which is relatively low in energy compared to microwaves). In general cooking with a microwave is actually going to destroy nutrients less than conventional heating (Schnepf and Driskell, 1993 Journal of Food Quality). Cooking food (no matter how you do it) can have positive or negative effects on the nutritional value. Cooking provides energy for chemical reactions that can degrade nutrients. Some cooking methods cause nutrients to diffuse out of the food (like boiling or frying in oil). Many foods (like broccoli) are better raw. Some foods (like corn and carrots) will have more nutrients available when cooked properly (burning food is generally bad). So I am not gonna through out my microwave, but I don't use it to cook everymeal I eat. As usual moderation and diversity are great rules. EAT MORE FRESH PLANT FOODS! You probably call these fruits and vegetibles. The nutrient content is high and most people don't get enough. Our ancestors ate a lot of fresh plant material everyday which gave them a lot more nutrients in their diets than we usually get. Processed plant components (foods like white flower and corn syrup don't count they are empty calories meaning they don't have the nutrients you need just the calories you probably get too much of allready).
Avatar universal
What effect does microwave power have on the rate of vitamin decomposition?  For example, if I cook veggies for three minutes at high power, will more vitamins be degraded than if I cook them for six minutes at 50% power?
Avatar universal
A study published in Lancet (1989; 913: 92-3) demonstrated high rates of change in microwaved food proteins not seen with conventional cooking. The authors warned that such effects on amino acids could be hazardous and “can lead to structural, functional and immunological changes.”

From this site (with more citations of scientific studies):

Try an experiment in your own kitchen by simply cooking two portions of the same food using microwave and conventional methods – you will be able to taste the difference. Why is that if there is no difference in the effect on the food cooked?

Another experiment you can try if you have high cholesterol is to avoid microwaved food between blood tests and see if there is a change in your cholesterol levels.

Avatar universal
I wish I knew the answer. Perhaps I get as much nutrition as always. (very health conscious) . Recently low income, moved from my beloved stove (all my life use) into NEW forever house with only microwave. Ever since the move, our stools have become somewhat soft. It's very bizzarre. I'm vegan. I almost exclusively only eat beans (That's FIBER!!! tons of it!)  I actually enjoy beans/lentils. If anyone has further comments I'd love to know. After one month of the same above results, We even tried Diatomaceous Earth, and whole pumpkin sees (in case of worms?) but nothing. Still soft stools. I swear this is due to almost exclusive microwaved food. We now have a new toaster oven and crock pot slow cooker. Look forward to washer/dryer or new stove for new year! Yippee! But Just curious, what was this all about? was it the microwave? did it kill the nutrients or fiber??? Is there secret mold in my house? ? radon? anything??? It's historic.
Avatar universal
PS. With the DE, (good for hair and skin, I guess). I commenced* taking Calcium, B Vitamin Nutritional Yeast... (it's super yummy anyway!) zinc filled sesame seeds, acidopolis Probiotic stuff, 100% pure health food cranberry juice, anything, my adult acne has never been better! I don't know if it is all that, or due to the microwave NOT killing the nutrients in my broccoli. (also great for skin!)

* I always took this stuff, off and on through out my life.
Avatar universal
http://www.alive.com/1403a4a2.php   no longer on the web, can find no other specific articles showing danger of microwave cooking.

The Lancet article ? would have to read it to see what it actually says, but most other credible sources find no danger.

Unfortunately in nutrition there are way too many unsubstantiated theories
Avatar universal
I don't think you should be using 'feeling' when it comes to such important and emotive subjects.  A quick look on the internet at bona fide scientific sources shows that microwaving CANNOT change the molecular structure of food and in many cases does less damage than conventional cooking.
Avatar universal
I am a student of electronics engineering, water does not have a close resonance frequency with microwave. Water at its stable state does not have resonance frequency with mocrowave which is at 2.4 ghz or 2.4 billion cycles per second. But water molecules bombarded with microwave will have its electrons influenced to move at this very high cycle of vibration causing it to heat up and boil. Water can not have a resonant frequency of 2.4 ghz but  the microwave as an electromagnetic energy accelerates the water molecules to this frequency.
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