Defending Olive Oil’s Reputation

by Mark Sisson
Mark’s Daily Apple

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Olive oil's reputation has been besmirched. It isn't the magic life elixir fueling the teeming hordes of Mediterranean-dieting, crusty bread-eating, moderate wine-drinking centenarians, but it doesn't deserve to be tossed in the trash heap with soybean, grapeseed, corn, and canola oils. I sense that it's fast becoming a "fallen fat" among our crowd and I think it's a darn shame. Are a few extra grams of linoleic acid, one or two unfortunate incidents of adulterated oil, and gushing praise from vegans, vegetarians, and the American Heart Association alike enough to turn us against a staple, phenolic-rich food sporting several thousand years of storied history?

Allow me to explain myself. Early this week, I got an email from a reader: "I often roast my veggies with EVOO. Would butter be a better alternative, or are the fats in EVOO just as well?" This is an extremely common, totally innocent question. I get similar questions a few times each week. Moreover, I've noticed a general undercurrent across the paleosphere of folks avoiding olive oil altogether, either because it isn't necessary for health, has too much linoleic acid, or it's too prone to oxidative damage when exposed to the elements (heat, oxygen, light). I'd like to address each of these, particularly the oxidative stability. And I'll answer whether I think we can cook with it or not.

Do we need it?

Now, you don't need to eat olive oil to be healthy – agreed. I would enjoy life less without good extra virgin olive oil, but I could be healthy without it and I can see why people would find it unnecessary. Besides, good olive oil can be hard to find or expensive, while a slab of good grass-fed butter is almost always more affordable.

Is there too much omega-6?

Olive oil does have a fair amount of linoleic acid, with some varieties reaching concentrations of 20%. Using such a variety for the majority of your added cooking and salad fat – especially on a high-fat Primal Blueprint eating strategy – would mean eating excessive amounts of omega-6. Note, though, that some olive oil varieties are far lower in linoleic acid, and most extra virgin olive oil runs about 10%. Two tablespoons of the average stuff gives you about 2.8 grams of linoleic acid. That's less omega-6 than most lard and poultry fat, if you're counting, especially if you use it sparingly as a drizzler or in salads.

Isn't olive oil too unstable for regular eating? What about the oxidation?!?

As for the oxidative potential of olive oil, that depends on a few things. Your olive oil is only as unstable as its environment. Heat, light, and exposure to oxygen all impact the oxidative stability of olive oil, as does the presence of antioxidants and phenolics. Of course, this is all works in a dose dependent manner; the more heat, light, and oxygen exposure, the greater the oxidative potential, while the more antioxidants and phenolics present, the lower the oxidative potential. Ultimately, it's up to you to source good quality oil and store and handle it properly. If you buy your olive oil at Costco in two-gallon clear plastic jugs, don't be surprised when it doesn't hold up as well as the extra virgin deep green olive oil that leaves streaks of olive sediment behind and burns your throat going down. If you store your olive oil next to the stove, often forget to secure the cap, and expose it to plenty of kitchen lighting, it's not going to last very long.

What about heating it? Should you ever cook with olive oil?

Surely heating such a fragile plant oil will render it inedible, toxic, and liable to result in oxidized serum lipids if eaten. Right? Not so fast. While subjecting extra virgin olive oil to high heat can alter the taste, it's actually fairly resistant to oxidative damage from cooking. Let's take a look at some studies to make sure:

In one study, the authors heated various oils to "deep-frying conditions" and checked oxidative markers every three hours. The olive oils made it 24-27 hours of constant high heating before reaching the maximum legal value of heat damage. Not bad, and it's not like you're going to use your olive oil to deep fry anyway.

Despite being heated at 180 degrees C (356 degrees F) for 36 hours, two varieties of extra virgin olive oil exhibited strong resistance to oxidative damage and retained most of their "minor [phenolic] compounds."

But then there's this study, in which subjects were given heated olive oil meals, heated safflower oil meals, unheated olive oil meals, and unheated safflower oil meals. Both of the heated oils and the unheated safflower oil resulted in elevated postprandial oxidative markers, while eating unheated olive oil resulted in none. Note, though, that the olive oil was probably refined or light (otherwise they would have called it "virgin" or "extra virgin") and thus devoid of significant phenolics with antioxidant properties. Also, the oils were heated at 210 degrees C (410 degrees F) for eight hours, which seems excessive. The home cook sauteeing some shrimp and onions in white wine and EVOO is unlikely to hit 210 degrees C, let alone stay there for eight hours.

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March 24, 2011

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