By now, the average educated adult knows that for healthy eating, lard is a bad fat, cottonseed oil not much better, and olive oil just dandy as long as it isn't heated too much. Now a new study published in Neurology-- which will probably come as a huge surprise to Dr. Dean Ornish--shows that people who use lots of olive oil, even in cooking, have a considerably lower stroke risk than people who don't use it at all.1 The French study of 7,625 people aged 65 found a 41 percent reduced stroke risk in heavy olive oil users. In fact, the participants were divided into three groups and those with the highest olive oil intake had a whopping 73 percent reduced stroke risk compared to the group with the lowest olive oil intake. The effect remained consistent even after controlling for other factors such as overall diet and health conditions, showing that olive oil confers benefits even independent of the Mediterranean Diet of which it is a cornerstone.2 Prior to this study, research had indicated that high olive oil consumption reduced heart attack risk, but this new research points to the fact that its benefits extend to other areas of health, and in a big way.
Before you rush to Costco for a giant tub of olive oil to guzzle, consider that the researchers caution that the results might actually indicate something other than the miraculous properties of olive oil. For instance, they say, olive oil consumers might be healthier, wealthier, and happier than those who rely on Safflower. On the other hand, as already indicated, the study did control for those factors, so olive oil emerges looking like a big winner. The key here is that you need to use only organic, extra-virgin, cold first-pressed, which is rich in phytonutrients. Studies show that in comparison to the pure stuff, processed olive oils don't necessarily offer any benefit at all. Although the report on the French study didn't mention what type of olive oil was tested, in France, virtually all the available olive oil is cold-pressed extra virgin.
Why is olive oil such a healthy fat compared to the typical fat added to commercial goods? First, olive oil contains a high proportion of antioxidants, particularly polyphenols, which have powerful anti-inflammatory properties.3 Studies have shown that one of the polyphenols, hydroxytyrosol (HT), has a particularly powerful ability to protect blood vessel walls. Also, the composition of olive oil differs from most commercial cooking oils in that about 75 percent of the fat comes in the form of oleic acid, which is a monounsaturated, omega-9 fatty acid -- and that's a good thing. Other oils with lower monounsaturated content are higher in omega-6 fatty acids, and high consumption of omega-6 fatty acids causes a build-up of harmful "non-esterified fatty acids," otherwise known as a NEFAs. NEFAs in the blood are associated with sudden heart attacks. Compare olive oil to soybean oil, which is only 50-55 percent monounsaturated, or safflower oil, which is only 15 percent.
The positive health benefits of the high proportion of monounsaturated fatty acids (MUFAs) in olive oil include reduction of overall cholesterol levels as well as of LDL cholesterol, and improvement in LDL to HDL ratios. Plus, the high ratio of MUFAS helps to regulate blood glucose levels and apparently, to lower blood pressure.4 Which brings us to the problem of cooking at high heats and the puzzling results of the French study. The thing is that any oil that is heated beyond the point at which it smokes can release carcinogenic free radicals, and most commercial varieties of olive oil have a low smoke point.5 In other words, it's generally not considered a great choice for cooking at high heats, since the negative impact of creating free radicals in heating cancels out the positive benefits the oil proffers.
On the other hand, those who cooked with olive oil in the French study clearly benefited. The reason might have to do with the quality of the oil they used. Some experts contend that refined olive oil has a smoke point of around 350 degrees, while high-quality extra-virgin has a much higher smoke point, up around 410 degrees.6 In any event, olive oil maintains its nutritional integrity even when heated to high temperatures, and even as it creates those carcinogens.
To be on the safe side, use olive oil only for lower-temperature cooking. If you throw in with the olive oil lobby and buy that the higher-quality product has a relatively high smoke point, simply heat your oil in a pan and notice when it starts to emit smoke. Voila! You've found the smoke point, and you need to draw the line before that. As I've said before, you can use avocado oil for high temperature cooking. Avocado oil has a very high smoke point by comparison to other cooking oils. It will not burn or smoke until it reaches 520 F (271 C), which is ideal for searing meats and frying in a Wok. Other good choices include grapeseed oil (485 F) or rice bran oil 495 F. Again, look for organic, cold-processed oil. One other possibility is Spectrum Naturals High Heat Canola oil, which can handle temperatures up to about 450 degrees F.
1 Norton, Amy. "Olive oil lovers show lower stroke risk." 16 June 2011.Reuters. 16 June 2011. <http://www.reuters.com/article/2011/06/16/us-olive-oil-idUSTRE75E66L20110616>
2 Mann, Denise. "Olive Oil Linked to Reduced Stroke Risk. 15 June 2011. WebMD. 18 June 2011. < http://www.webmd.com/healthy-aging/news/20110615/olive-oil-linked-to-reduced-stroke-risk>
3 "Olive oil, extra virgin." The World's Healthiest Foods. 17 June 2011. < http://www.whfoods.com/genpage.php?tname=foodspice&dbid=132>
4 Hensrud, Donald, MD. "Nutrition and Healthy Eating." Mayo Clinic. 16 June 2011. http://www.mayoclinic.com/health/food-and-nutrition/AN01037
5 "Cooking Oil Smoke Points." 18 June 2011. < http://www.goodeatsfanpage.com/collectedinfo/oilsmokepoints.htm>
6 "Heating Olive Oil." Olive Oil Source. 18 June 2011. <http://www.oliveoilsource.com/page/heating-olive-oil>