# Olive oil toxic when heated?



## Robin (Jul 20, 2009)

So someone was telling me olive oil can be toxic when used with high heat. Is this true? How hot is too hot? And what exactly is the toxicity? 

I use a lot of olive oil in my cooking. The only time I don't really use olive oil is deep frying. And then I use veggie oil but only because its cheaper. I've never heard of olive oil being toxic before. So how hot is too hot?


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## Andy M. (Jul 20, 2009)

All oils, including olive, will start to smoke when they get too hot.  The smoke point is different for different oils.  That smoking is an indication that the oil is breaking down.  If you allow it to continue smoking, the taste will be "off" and will ruin the flavor of the food you're cooking.  Allowed to go far enough, the oil could ignite and burn.

I've never heard of it's being toxic.


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## Snoop Puss (Jul 20, 2009)

Hi and welcome to DC. I think the problem is to do with breaking the fat chains in the oil. But there are lots of experts in this forum and someone with a better understanding of food and oil chemistry will be able to answer you in greater detail.

In the meantime, however, people here where I live make their own olive oil and use it for everything, even deep frying. Life expectancy here is very long, so I don't think toxicity is a serious problem.


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## jennyema (Jul 20, 2009)

It's not unique to olive oil.  Any and all oils become toxic once they've been heated past their smoke point.

When oil is hot eneough to smoke it decomposes.  The smoke is toxic and the oil generates free radicals.

Here's a smoke point chart:  Cooking Oil Smoke Points


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## BreezyCooking (Jul 20, 2009)

Olive oil is not toxic when used over high heat. I've been using extra-virgin olive oil for almost all my cooking needs - high heat included - for over 30 years. No problems, "free radicals" or not.


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## Scotch (Jul 20, 2009)

Check this article on the subject: 
Food Fried In Vegetable Oil May Contain Toxic Compound

And this:
http://www.news-medical.net/news/2005/05/02/9722.aspx


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## Scotch (Jul 20, 2009)

BreezyCooking said:


> Olive oil is not toxic when used over high heat. I've been using extra-virgin olive oil for almost all my cooking needs - high heat included - for over 30 years. No problems, "free radicals" or not.


I once drove 130 miles per hour on a deserted desert road and I didn't die.


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## BreezyCooking (Jul 20, 2009)

Hope that "dessert" road was yummy!!

Anyway, I am NOT giving up cooking with extra-virgin olive oil. Period. Every time you turn around someone is all-too-ready to blitz yet another food item. And then months later there's another flip-flop. Coffee, tea, wine, chocolate, etc. - now it's olive oil? Puhleeze. Do what you want. I don't buy into it anymore.

My cooking/eating mantra has always been:  Moderation in all things.  And I'm sticking to it.


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## Scotch (Jul 20, 2009)

BreezyCooking said:


> ...Anyway, I am NOT giving up cooking with extra-virgin olive oil. Period. Every time you turn around someone is all-too-ready to blitz yet another food item. And then months later there's another flip-flop. Coffee, tea, wine, chocolate, etc. - now it's olive oil? Puhleeze. Do what you want. I don't buy into it anymore....


How on earth did you get that out of this thread? The point is not to overheat your oils -- ANY cooking oil, especially highly unsaturated oils.


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## BreezyCooking (Jul 20, 2009)

What else could I assume?  If you overheat your oil to the point where it's "supposed" to be toxic, your food would be incinerated or at the very least inedible.  And you'd find that out immediately.  However, I saute & fry completely adequately over "high" heat, which was what was stated & don't consider it a health risk.

I just feel that even intimating that olive oil over high heat is harmful unnecessarily puts the fear of God into many people - especially those fairly new to cooking.  If they overheat their oil, they'll quickly find they can't cook properly in it.  Problem automatically solved without scaring them away from it.


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## jennyema (Jul 20, 2009)

Oil which has begun to *smoke* has broken down. The smoke itself is toxic and the oil is said to be unhealthy.

Not to mention that the flavor has entirely changed for the worse.

Of course you can cook with olive oil quickly over high heat without it smoking.  But when/if it does, then it's bad for you.


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## Scotch (Jul 20, 2009)

The problem is associated with reheating of oils, something most of us don't do -- except in deep fryers. Research has shown the practice to cause the formation of HNE, a toxin associated with several diseases, in highly unsaturated vegetable oils. 

Here's the conclusion from the University of Minnesota's press release: "HNE is a well known, highly toxic compound that is easily absorbed from the diet," said Csallany. "The toxicity arises because the compound is highly reactive with proteins, nucleic acids--DNA and RNA--and other biomolecules. HNE is formed from the oxidation of linoleic acid, and reports have related it to several diseases, including atherosclerosis, stroke, Parkinson's, Alzheimer's, Huntington's and liver diseases."

Ignore it if you wish, but don't discount the science just because you dislike the findings. 

Here's another article of interest from the National Women's Health Resource Center:

Reheating Vegetable Oil Releases Toxin: Study


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## Robin (Jul 20, 2009)

Wow I guess this is a passionate topic for some. lol. Thanks everyone. I don't know why anyone would get the oil that hot to make it smoke. But glad I have a better understanding. I can now correct that person who passed it along to me. Thanks.


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## Mark Webster (Jul 20, 2009)

I have never heard of olive oil being toxic. I have lived in Greece and Italy and have been a professional Chef over 30 years.


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## luvs (Jul 20, 2009)

olive oil shouldn't get that warm, anyway!


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## Scotch (Jul 20, 2009)

Mark Webster said:


> I have never heard of olive oil being toxic. I have lived in Greece and Italy and have been a professional Chef over 30 years.


I've alerted the university. They've agreed to call off the research project and have retracted their findings.


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## Scotch (Jul 20, 2009)

luvs said:


> olive oil shouldn't get that warm, anyway!


I think that's the point, along with not reusing it.


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## blissful (Jul 20, 2009)

Scotch said:


> I've alerted the university. They've agreed to call off the research project and have retracted their findings.


 This is just way too funny. Wouldn't that be a great way for the world to work.
If you denied your own existence, you would cease to exist.

The oil is not too hot if your food is not burned.


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## luvs (Jul 20, 2009)

with due respect, i don't give a plop! i'm keeping my olive oil!


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## Scotch (Jul 20, 2009)

What's your point? No one has suggested that you get rid of it. You're reading something into this thread and into the research that simply isn't there.


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## luvs (Jul 20, 2009)

yep!


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## Scotch (Jul 20, 2009)

Astounding!


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## GB (Jul 20, 2009)

Seems we have started to stray from the topic at hand. How about we get back to discussing the toxicity of olive oil please.


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## Thaicooking (Jul 22, 2009)

I've used olive oil for cooking for many year, but I've never noticed that it's smells weird when it's too hot. Thank you useful post!


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## bigdaddy3k (Jul 22, 2009)

jennyema said:


> When oil is hot eneough to smoke it decomposes. The smoke is toxic and the oil generates free radicals.


 

FREE THE RADICALS! COLD oPRESSion RESULTS IN EXTRA VIRGINS!!!

I just report the news, I don't make it.


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## TheMetalChef (Jul 22, 2009)

Scotch said:


> Check this article on the subject:
> Food Fried In Vegetable Oil May Contain Toxic Compound
> 
> And this:
> Food fried in vegetable oil contains a highly toxic compound - HNE (4-hydroxy-trans-2-nonenal)



Nice. 

Linoleic acid breaks down into a toxic chemical at high heat.

Folks, deep fry your food in peanut oil (one of the highest smoke points out there) and (as if you needed more reasons) *stay the hell away from fast food*....


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## dadouger (Jan 4, 2012)

*What about Olive Oil*



Scotch said:


> Check this article on the subject:
> Food Fried In Vegetable Oil May Contain Toxic Compound
> 
> And this:
> Food fried in vegetable oil contains a highly toxic compound - HNE (4-hydroxy-trans-2-nonenal)



Scotch, all the information you present is valid, IF we were talking about Vegetable Oil.  All of us are curious about the daily uses of Olive Oil.  My research has turned up nothing besides the obvious of not using to excess or overheating. 

Please let me know if I missed anything.


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## Andy M. (Jan 4, 2012)

dadouger said:


> Scotch, all the information you present is valid, IF we were talking about Vegetable Oil.  All of us are curious about the daily uses of Olive Oil.  My research has turned up nothing besides the obvious of not using to excess or overheating.
> 
> Please let me know if I missed anything.



Hi dadouger, welcome to DC.

You missed the fact that olives are vegetables and olive oil is a vegetable oil.


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## forty_caliber (Jan 4, 2012)

This topic came up a while back.  There was a fairly productive discussion in this thread.  

There is conflicting information out there about this topic.  From a pure scientific standpoint it may be possible to make olive oil toxic but on the other hand repeating the same results in the kitchen by accident is unlikely.

Here is a good general reference on olive oil.  The Olive Oil Source | Everything but the Olive

.40


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