In my previous life as an e-learning developer, I wrote a Whole Foods training course on DSHEA, a U.S. act which regulates labeling on dietary supplements. In a nutshell, makers of supplements can’t claim that a supplement cures any diseases. That’s why your bottle of Vitamin C says “boosts immune system” rather than “eases the symptoms of the common cold.” The same law applies to foods.
Since this brush with the law, I’m more apt to notice the often erroneous claims that so-called health gurus make about food. So when Dragana Brown said “olive oil is more stable than any other oil”, I had to spend an hour on the internet verifying the validity of her statement (see previous post about Dragana’s cooking class for context).
Turns out there’s some science behind her statement, but it took a little digging to get there.
Oxidation and antioxidants (in layman’s terms)
Flashback to high school chem class: atoms are made up of protons, neutrons and electrons. Atoms like an equal balance of positively-charged protons and negatively-charged electrons.
Add or take away an electron, and the atom becomes woefully unstable. This process of gaining or losing an electron is called oxidation.
Cue free radicals: these are the unstable bad boys that form during oxidation and therefore carry a charge. Once a free radical is formed, it loots the body for susceptible atoms from which it takes or gives
away extra electrons. In the body, free radicals can turn once healthy and stable cells into damaged goods. Take a blood cell, for example. Blood cells contain cholesterol which can become oxidized by free radicals. The so-called “bad” LDL cholesterol that you hear about is bad because it does scary things when it becomes oxidized. To retrieve its precious neutrality, oxidized LDL binds to “microphage” cells in the blood vessel wall. A build-up of these LDL-microphage combos causes a build up of nasty foam in the cell well, which can lead to blocked arteries and heart attacks.
So what do antioxidants do? These atoms get between free radicals and healthy cells, providing free radicals with their electron fix. When antioxidants neutralize free radicals, they become oxidized themselves. That’s why we must constantly replenish our supply of antioxidants.
Take a moment to marvel at this cycle of life!
Antioxidants in olive oil
Surprise: olive oil contains loads of antioxidants, particularly “flavenoid polyphenols”. These guys prevent LDL oxidation, and therefore, damage to blood vessels. That’s why you always hear about olive oil being good for the heart; the better your arteries, the less work the heart has to do to pump blood through them, the less likely the heart is to spazz out and stop working.
Olive oil, antioxidants, and hot hot heat
Flash back to high school chem lab: heat is a catalyst for molecular change. Apply enough heat to oil, any oil, and its constituent molecules change. In particular, heating oil can decrease its antioxidants and create a slew of new nasty chemicals (such as trans fatty acids, the stuff found in hydrogenated oil which is created by bubbling hydrogen through super-heated vegetable oil).
Finally, we’re back to where we started. Some scientists in Turkey studied the effect of heating olive oil, sunflower oil and soy oil to 180 degrees C. While all oils suffered reduced antioxidant potential, olive oil retained the most antioxidants [Durak et. al, 2004].
The reason seems to do with the monounsaturated-ness of olive oil. But this is getting into some hairy chemistry and now it’s time to make dinner. We’re having a Sunday roast, and you can guess what we’re tossing the vegetables in. Now, pass the polyphenols, please.
Further reading:
The World’s healthiest foods: Olive Oil
Olive oil chemistry
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Thank you, Monica… I’ve long heard that oils are best added AFTER cooking, and you’ve explained why. The nuns at Mt. Assisi would be so proud of you remembering your chemistry so well. The way you described anti-oxidants made so much sense. Excellent visual. Good job!