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Along the lines of this recent question, how bad is microwaved food? PMPD makes a similar claim about how it destroys all the nutrients. I don't microwave often but find uses sometimes, like spaghetti squash, yams, and reheating leftovers. My suspicion is that it's probably no worse than other forms of heat and might even be better given that microwaves target heat dissipation at water molecules instead of all of them.

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I've been curious about this issue a bit lately. What I've looked into about microwave cooking is essentially: Does it destroy nutrients and does it create dangerous compounds?

Elimination of good stuff:

Perfect Health Diet discussed the effects of microwaves on reducing flavanoids, finding the effect to minimal or better than other cooking methods in green tea, onions, strawberries, purple potatoes, and 9 assorted vegetables.

This study by the national center for home food preservation examined the effect of microwave blanching vs. boiling water blanching on the retention of several vitamins in turnip greens.

As you can see, boiling caused an almost complete loss of vitamin C, folic acid, thiamine, and riboflavin. The effect was significantly less when microwaved.

The effect of microwaving vs. baking on spinach in this study found that ascorbic acid retention was 47% vs. 51% (a relatively minor difference) and folate retention was 101% vs. 77%, meaning that folate was not decreased at all in the microwaved spinach, but was notably reduced in the conventionally cooked spinach).

Microwaving has been shown to cause a decent loss of usable vitamin B12, often about 30-40%. This is fairly consistent with other cooking methods on B12.

Overall, most studies I have seen show vitamin loss is not much different in microwaved food than food cooked other ways. Boiling food actually appears to cause the greatest loss of vitamins and minerals by extracting the nutrients into the water.

Production of bad stuff:

A lot people enjoy bacon around here. Studies have found that microwaving bacon produces less N-nitrosamines and N-nitrosopyrrolidine (potentially carcinogenic compounds) than frying.

Numerous studies, including this one and this one, have found that microwaving produces less carcinogenic heterocyclicamines in meat than other cooking methods.

Peroxidation of polyunsaturated fatty acids during cooking is a concern of mine and it appears that microwaving and conventional cooking methods don't differ significantly in their production of these compounds (see this study and this study)

Acrylamide, a possible carcinogen produced when cooking starchy foods like potatoes, may be increased in microwaving compared to frying and baking. I've found some contradictory results regarding this though, so I'm not fully willing to say one way or another.

Some people seem very opposed to the idea of microwaves. I can understand that kind of knee jerk reaction, but from what I've seen the effect of cooking with microwaves is just like any other method of cooking and likely is not "bad" relative to baking, frying, or boiling. Don't fear the microwave, neolithic invention though it is.

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Boiling is likely to extract water-soluble vitamins sigificantly. When you look at your numbers using dry heat and microwaves, there's essentially no difference. – Matt Mar 29 2012 at 12:00
Nice answer - linked references and graphs! – balor123 Mar 29 2012 at 18:28
@Matt-I agree, in fact boiling seems to extract fat-soluble vitamins from vegetables when they're not dissolved in fat (e.g. beta carotene from carrots). I once heard someone say (Michael Pollan maybe? I'm not sure) that if you boil vegetables you should drink the water. I'm editing my answer to note that. – Mscott Mar 29 2012 at 21:32
It would be expected that a vegetable would nearly as easily give up fat soluble vitamins, after all, veggies don't have a lot of fat to partition fat-soluble compounds into. – Matt Mar 30 2012 at 0:25
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Chemists are not convinced there's any microwave-induced reactions. We, chemists, use microwaves in our experiments and that's only because it's an extremely efficient way to heat things. Any degradation that takes place is simply because of thermal effects.

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A paleotarian using a microwave just seems so... wrong. It just sucks the spirit out of the whole ancestral concept. Maybe it's not going to give mutate your cells, but the point is that food is nature's gift. And all we human's can think to do is use technology to "improve" it in any way we can. Lets genetically modify the seeds to make it hardier. Lets pastuerize it to make it last longer. Lets inundate livestock with growth hormones and antibiotics. And lets microwave it up so we can shove it into our mouths as fast as we can. Gee, thanks mother nature.

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we should make a firepit in the backyard and go squat around it while our meat roasts on a spit... – gydle Mar 29 2012 at 14:24
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Sounds like someone doesn't cook for a family on a regular basis! I cook - using other techniques - breakfast and dinner EVERY day from scratch, while I line dry my laundry, use cloth diapers, chop and peel and prep and take care of children and make food for a husband who works a LOT. I use my microwave to then heat up a paleo lunch of leftovers almost every day. It's the only way I can manage to keep that kind of food on the table when we get home from playdates or appointments and the kiddos are cranky. Other moms toss crackers at their kids. I'd rather toss a microwaved paleo meal. – Sarah Mar 29 2012 at 14:24
Thanks for the memorable phrase: "suck the spirit out of [a] concept." – Dorado Galore Mar 29 2012 at 17:21
Agreed it's not a Paleo cooking method but I'm willing to tolerate some deviations with some understanding of what the implications are. – balor123 Mar 29 2012 at 18:31
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People, please stop using microwaves, they cause terrible interference with wifi and old cordless phones, and set off all the low end radar detectors off making everyone slow down.

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No harm in using it. food loses some of its good stuff when you cook it anyway. Now if we lived in a fallout universe... then yes dont you ever use the microwave.

but we dont live in a game universe and its a quick way to get hot food down your throat and into your belly. go for it. I do it when I am pressed for time and only when I am pressed for time.

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Don't do it folks!! I don't care what the "experts" say about the microwave not being bad.....IT IS!!! Google all the crap. If you're going to go through all the trouble to source the BEST food you can, don't go destroying it with the damn microwave - for what, saving 2-3 minutes. NOT worth it.

Seriously, warming food in a skillet, cast iron, or saute pan MIGHT take an additional 2-3 minutes for a serving...sometimes damn near the same time compared to a microwave. Don't have time?? Come on! do another chore in the kitchen while it's warming.

NOT even steaming! I'm not a scientist, but if it changes the chemical and molecular structure of food, why would you think it's still ok?

I'm pretty good in the kitchen, but still, the AVERAGE person cooking paleo-style should be able to put food on the table from start (prep) to finish (plating) in about 25-35 minutes. During that time, catch up with the spouse, kids, buddies, have an adult beverage, and chill it out! Make time!

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Okay, I don't use a microwave AND I think that there is no harm in using one. Best of both worlds? But seriously, there is no science behind the claims that it somehow "destroys" all the nutrients with it's magic waves. – JeJ Mar 28 2012 at 23:02
What's an adult beverage? – Namby Pamby Mar 28 2012 at 23:05
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Also, what's the reason for not steaming? Steaming has been practiced since time immemorial. – Namby Pamby Mar 28 2012 at 23:07
@Namby, I'm guessing it's a beverage that's naked, or helps you and an attractive someone get that way. :) – raydawg Mar 29 2012 at 0:15
Oh, I thought he was talking about Yoohoo. – Namby Pamby Mar 29 2012 at 4:18
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In terms of nutrients, microwaving probably isn't worse than other cooking methods. But, in terms of taste, texture, etc., I think microwaves are craptastically poor cooking devices except as an alternative to steaming veggies in a steamer.

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+1 for use of craptastically. :) – raydawg Mar 29 2012 at 0:14
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I used to worry about that. But seriously, I don't have the time to worry. Without my microwave, it will take me an additional hour to cook my meals. I also wanna know whether mini electric ovens are healthy, compared to, say, gas ovens?

Our beloved hunter-gatherers supposedly cooked their meals over a bonfire. So what are we missing out by using microwaves, electric ovens, crock pots, steam pots, and George Foreman grills?

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Actually, aren't microwaves saving us from all that carcinogenic char? ;) – Karen P. Mar 29 2012 at 0:14
Ur assuming that the carcinogenic char is from cooking over an open fire. Don't u think if this mode of cooking was so prevalent that we would have evolved enough to tolerate carcinogenic char. I fail to understand the raw meat / rare cooking argument. I like my steak well done and I think many Paleos probably liked well-done meat vs. something raw or rare. If eating welld-done or almost burnt meat induced cancer, we would've become tolerant by now, since open-fire cooking is so prevalent. – Namby Pamby Mar 30 2012 at 14:42
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Cooking food in any way is going to damage and reduce some nutrients, whether that be in the microwave, oven, or grill. In general, don't use a lot of water or overcook food to reduce the possibility of this in all capacities. I would assume it couldn't possibly kill all the nutrients, because at my university they study many different varieties of potatoes and our prof showed us a comparison of various cooking methods- boiling lost the most nutrients, followed by steaming when the skin was cut, then baking/microwaving tied for most nutrients maintained. Unless the potato is exceptional, I think this could be applied across other vegetables. It is difficult to render a food "dead", or completely nutritionally depleted, so I doubt the microwave has the capacity to do this in 30 s or however long you are heating your meal up.

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Man, I also just googled this and found "People who avoid "irradiated" food have no hesitation about microwaving their food. It's the same thing (just a different wavelength of radiation)". That's like saying your desk light is like an X-ray or radio wave- it's just a different wavelength at the end of the day! facepalm – JeJ Mar 28 2012 at 21:17
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Okay, warning, don't google "microwave safety" unless you want to hear people butcher every concept of physics. People compare it to nuclear radiation (hence "nuking") and actually seem to believe it- better tell them to get out of the sun, quick(!), b/c microwaves are still 1000's of times less powerful than UV rays.... – JeJ Mar 28 2012 at 21:22
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Microwave FUD is one of the worst kind out there when it comes to health, and that's saying something... – Wisper Mar 28 2012 at 21:35
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+1; I absolutely hate it when people act high-and-mighty about the fact that they don't use microwaves because that would be soooo unhealthy. It's completely baffling how many people don't do any research or use any common sense when making or believing these claims. – OddBallin Mar 28 2012 at 22:11
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+1 to the comment above by OddBallin. I don't own a microwave, but the top three reasons why are: I'm too cheap and lazy to buy one; I don't have the counter space to spare for it; and it forces me to actually cook things with care. Health doesn't figure into it at all. – air_hadoken Mar 29 2012 at 12:25
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