Deep-Frying Toxins

Deep-Frying Toxins
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Volatile toxins created by deep-frying may pose a respiratory risk.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Frying is not just bad because it destroys more nutrition, and oil is such a waste of calories. We should never deep-fry foods because of the toxic volatile carcinogens that are produced. In fact, we shouldn’t even let anyone deep-fry in our house.

Like second-hand smoke, they may be putting your whole household at risk because of the air pollution created by deep frying. If they insist, though, we definitely want to open the windows; keep the kitchen ventilated.

And some oils are worse than others. What’s the worst oil to deep-fry with? Canola, coconut, safflower, or extra virgin olive? The worst is coconut, which should not be used, period.

What’s the least harmful? Canola was the oil generating the least amount of potentially toxic chemicals.

Please consider volunteering to help out on the site.

Image thanks to Kristin via flickr

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Frying is not just bad because it destroys more nutrition, and oil is such a waste of calories. We should never deep-fry foods because of the toxic volatile carcinogens that are produced. In fact, we shouldn’t even let anyone deep-fry in our house.

Like second-hand smoke, they may be putting your whole household at risk because of the air pollution created by deep frying. If they insist, though, we definitely want to open the windows; keep the kitchen ventilated.

And some oils are worse than others. What’s the worst oil to deep-fry with? Canola, coconut, safflower, or extra virgin olive? The worst is coconut, which should not be used, period.

What’s the least harmful? Canola was the oil generating the least amount of potentially toxic chemicals.

Please consider volunteering to help out on the site.

Image thanks to Kristin via flickr

Doctor's Note

For more on deep frying, check out these videos:
Cancer Risk from French Fries
Prolonged Liver Function Enhancement from Broccoli
Estrogenic Cooked Meat Carcinogens

And check out my other videos on cooking methods

If you haven’t yet, you can subscribe to my videos for free by clicking here.

26 responses to “Deep-Frying Toxins

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  1. So how do you feel about a little olive oil in a stainless steel pan for cooking up say a stir fry? Something in the area of a couple tablespoons. If that’s no good then what do you recommend? BTW I love this site.

  2. This video is titled “deep frying” but does this also apply to normal frying? I love coconut oil for all its topical uses, and my roommate recently started using it in the frying pan, in place of butter/nonstick spray. A few friends of mine told me that this is dangerous as it becomes carcinogenic (they said it especially happens with cold-pressed oils). Are they right? Thanks.

    1. Coconut oil is covered by Dr. Greger. It is indeed an unhealthy food to use, as are all oils.
      http://nutritionfacts.org/video/is-coconut-oil-good-for-you/

      Coconut oil manufacturers constantly point a finger to the medium chain saturated fatty acids being used for energy expenditure and therefore not being disposed of as fat in adipose tissue. Coconut oil does indeed contain medium chain fatty acids and this may be metabolized differently but there are very few studies to make the conclusion that coconut oil is “ok” or that medium chain saturated fats are negligible. A tablespoon of coconut oil has about 12 grams of total saturated fat. about 8 grams of this is medium chain saturated fat and about 3.7 grams of this is long chain saturated fat. We have an abundance of evidence concluding that long chain saturated fats are harmful so we cannot consider this oil a healthy option based on that alone.

      As far as minerals and vitamins go, there is not one significant vitamin or mineral in coconut oil. The only vitamin present in a tablespoon of coconut oil is .1 micrograms of vitamin k which does not even register as a percentage of daily value. Its also absent of any omega 3 fats. Just looking at coconut oils nutritional profile we see that it is clearly a junk food. Junk food is by definition empty calories.

      http://nutritiondata.self.com/facts/fats-and-oils/508/2

    1. Peanut oil is extremely rich on omega 6, with a ratio close to 4400:1 of omega 6:3. An adequate ratio is 4:1 so this far exceeds what we should strive for. This is important because if the ratio is off, then omega 3 ALA cannot be converted to DHA and EPA.

        1. So – in terms of carcinogens and Omega 3 oils, Canola is the healthiest other than flax. I have heard that Canola is bad for frying because Omega 3 oils, while being heart healthy, oxidize more under heat, so it’s possible that your best bet for oils is in salad dressing.

  3. I work in a restarant that changes there deep fryer grease 1 time every 2 weeks. I have asthma and before the 1st week is out I’m using my rescue inhaler. This has been going on for years now. Is this dangerous to my health?

  4. Canola oil is extracted from rape seeds, high in omega 3 which at high temperatures turns into trans fats. Worse than saturated fat for cholesterol levels. Canola oil should only be used unrefined, cold pressed, and for salads as all omega 3 oils denature at 325F or 160C. As advised by Dr. Greger avoid deep frying.

  5. Recommending canola as a preference for deep frying as a healthy choice is a bit like recommending coca cola to athletes because dehydration is so detrimental to performance.

    1. Good analogy, but I never heard him recommend deep frying in canola oil. What he says is “canola was the oil generating the least amount of potentially toxic chemicals” however this doesn’t mean canola oil-based deep fried foods are safe and healthful.

    1. I’m not sure. If you are deep frying it looks like canola oil is best, but I would flood the meal with other whole foods like raw and steamed veggies to help counter the higher fat meal. Using sweet potatoes and/or blue, red, and gold potatoes are a better choice.

      1. I love words but for the life of me I couldn’t figure out what you meant regarding “win”. I researched the word and still was unsuccessful. Will you explain?

        1. They used shadow-quotes around win to imply that it’s kind of an empty win for canola oil. It produces the least amount of volatile toxins, but conclusion still being to never fry foods, so it’s not really a win is it.

  6. What is the basis for the opposition to canola oil? Up until recently I believed that canola oil was a less expensive alternative to olive oil due to its similar health profile, being a monounsaturated fat, with a higher heating point, as described by this article. I thought it was safe to cook with and safe to bake with.

    In the past couple months a couple of people have talked to me about the dangers of canola oil. They say there’s a deal with the Canadian government to sell this stuff for cheap and that it’s only passed off as healthy when it’s actually poison. A non-argument I’ve heard is that canola oil comes from RAPEseed. Usually whoever is telling me this pauses for effect. I usually just stare blankly, as if someone had just revealed that pine nuts are also called PIGnolias, or had referred to an orange as a NAVEL. I don’t care if canola comes from rapeseed, murderseed, larcenyseed, or assaultseed, so long as it’s healthy and safe to eat. It’s just a name, right?

    One last thing I’ve read but haven’t found any scientific articles on–if anyone could help out here–is that a lot of “olive oil” is not really olive oil, but canola oil with olive flavoring. I am wondering if this is like how some “honey” is highly processed, even bulked up with corn syrup, and has no health benefits of raw or organic honey. I suspect that a lot of “honey” is just flavored corn syrup, considering how cheap some honey is and where it comes from. If anyone can help clear up the labeling of olive and canola oils, or would like to comment on the labeling of honey, that would be great.

  7. Okay, deep-frying is not really a good idea. However what about air-frying with very little or no oil with a well adjusted temperature control? What temperature is acceptable? 160 … 180°C?

    1. Hi Klaus. Great question. The main concern is acrylamide. A found an interesting study that shows that pre-treating the potatoes (either by soaking or blanching) and then air-frying reduces the acrylamide content in potatoes. The temperature they used during the study was 180 degrees Celsius. Read more here. I think air-frying is a healthier alternative to deep-frying if you use a very little amount of a healthier cooking oil. I hope that helps.

  8. Deep fried food just should not be eaten considering the cancer risk, but also from the massive amount of free fat. Many of the carcinogens are quite stable and will not oxidize, or the oxidization product is a carcinogen too. It’s kinda like my patients that think they are helping themselves by smoking “organic cigarettes.” Best to just avoid completely.

    Dr. Ben

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