Olive Oil Dangers – What you should know

Sometime in life, a good thing can have an undesirable flip side and olive oil is definitely a good example. As wonderful as this oil is, it can produce artery-damaging free radicals when you fry foods in it and toxins if overheated. To be fair, this is true of all cooking oils, but today, we’re talking about my favorite of all oils: olive oil.

Without boring you with a chemistry lesson, suffice it to say that the chemistry of olive oil changes when it is sufficiently heated. This change is what creates the damaging free radicals and toxins.

So what the heck are free radicals? The short answer is when an electron is torn loose from its atoms; the atom (now a free radical) wants it back really bad. So, the atom (free radical) goes in search for an electron anywhere it can find one, a process called oxidation. If that electron hungry atom happens to be traveling around in your blood stream, it will steal electrons from your artery walls. The once hungry atom has it’s electron and goes happily on its way (now no longer a free radical). However, your arteries take exception to having their electrons stolen and react in a variety of undesirable ways which include hardening. In addition to hardened arteries, a variety of inflammatory diseases are associated with free radicals.

Olive oil will produce free radicals if you get it too hot. Therefore, to keep olive oil healthy, never bring it to the smoking point because, in addition to the formation of free radicals, the smoke contains toxic elements that are mutagenic and carcinogenic and the foods you are frying may contain toxic substances. Bad juju. (Note: Remember, this law of frying with oils holds true for other oils as well.) Let’s take a quick look at the smoke point for the various types of olive oil.

  • “Light” Olive/Refined Olive – smoke point 470°F (243°C) –  Best for sautéing and deep fat frying.
  • Virgin olive oil – smoke point 420°F (215°C) – Best for oven cooking or stir frying
  • Extra virgin olive oil – smoke point – 405°F (206°C) –

Okay, now we know not to bring our olive oil to the smoke point, but what effect does heat have on it? Studies have shown that given enough time, olive oil will lose some of its nutritional value. Studies state that olive oil may lose its nutritional value and produce toxins in high heat cooking. That begs the question, how hot is too hot? The answer to that question is currently in debate in the scientific community. The variables in this debate include cooking temperature, type of oil used, length of time the food is cooked, the type of food being cooked and the quality of the olive oil.

The nutritional value of olive oil used in frying or deep frying partially depends on the quality of the olive oil and type (refined, virgin or extra virgin), frying time and acidity of the oil. For instance, if extra virgin olive oil is heated above 200-250?F (93-121?C) for over 10 minutes, there is a marked reduction in tocopherols (vitamin E) and valuable phenols. Keep in mind the average temperature for stove top cooking ranges from 375-525?F (191-274?C). The longer you leave the oil on the stove, the hotter it will become, even on a low setting.

As for the toxic elements produced from heat, according to a recent study at Fred Hutchinson Cancer Research Center, when oil is used for deep frying, potentially carcinogenic (cancer causing) compounds are

formed. The type of carcinogen produced depends on the type of food fried. The study states that toxic compounds are increased by increasing the length of time cooking and by reusing the oil. To make matters worse, deep frying also produces foods which contain “high levels of advanced glycation end products” (AGEs) which are associated with chronic inflammation and oxidative stress. For instance, if you deep fry a chicken breast for 20 minutes, it will contain 9 times the AGEs as a chicken breast boiled for an hour.

In spite of all this bad news, there’s a good chance you’re not going to stop frying foods and there’s an absolute fact that I won’t. So what do we do to keep ourselves out of dangers way? I use olive oil exclusively in my kitchen. To minimize the dangers, I will:

  • Use refined olive oil for deep frying
  • Make sure my oil is fresh (less than 6 months old to avoid possible rancidity)
  • Parboil or steam foods prior to frying to reduce frying time (This works great for chicken and potatoes. I have never tried it with pork or beef.)
  • Only use the olive oil one time (I’ve been guilty of reusing my olive oil in the past. I won’t do that anymore.)
  • Eat foods high in antioxidants to scavenge free radicals.

Below is a recipe I use for fried potatoes that everyone who likes potatoes seems to like. If you have any recipes using olive oil for frying, be sure and share them. Let’s all help each other stay healthy.


My recipe for fried potatoes:

Scrub potatoes then cut into 1/2″ pieces (I leave skins on) then rinse to remove starch

Add potatoes to cold water with a shake or two of salt

Bring to boil and simmer for about 10 minutes

Drain potatoes well

Bring olive oil to frying temperature (I test with a drop of water in the oil. If the drop spatters, the olive oil is ready.

Add potatoes and fry until brown (usually 8 to 10 minutes)

P.S. I cut up onions and garlic and add to the potatoes during the last 3 to 4 minutes they are frying.


Now go have fun and relax.

8 thoughts on “Olive Oil Dangers – What you should know

  1. Is it correct to assume that using Virgin Olive Oil to pop corn on the stove is safe since it is in the oil for such a short time?

    1. Sodium benzoate is metabolized in the liver to form hippuric acid. It is then excreted in urine. If you avoid sodium benzoate for the most part (it’s almost impossible to completely avoid) you should have no worries.

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