It all starts with the famous "Seven Countries Study,” which was the first to find heart-health benefits in the so-called Mediterranean Diet.
Subsequent studies confirmed that people living in the countries that surround the ancient sea enjoy better heart health, compared with Northern Europe or the US.
But as a reader reminded us recently, folks at the Weston A. Price foundation, whose domain is traditional diets and their health effects, have taken pains to highlight some inconvenient truths about the Seven Countries Study and the "official" Mediterranean Diet.
It turns out that the Greek and Italian peoples in the Seven Countries Study ate diets that bear little resemblance to the the idealized "Mediterranean Diet", to which most nutrition gurus say we should aspire: one full of veggies, fruits, beans, and fish, with modest amounts of whole grains and olive oil and only small amounts of meat, poultry, and cheese.
Indeed, such a diet is ideal for optimal health. But it isn't what most Mediterranean people ate then or eat today.
Typical Italians, Greeks and Spaniards of the 1960's and 70's, living when and where the famed Seven Countries Study occurred, ate lots of meat, cheese, refined white bread, white pasta, not much fish at all, and modest amounts of greens. And that picture hasn't changed much in the intervening decades.
The author of a new olive oil health review puts her finger on an explanation that's obvious in hindsight, because she and other researchers have found a key part of the missing puzzle of the Mediterranean Diet: the potent antioxidants in extra virgin grade oil, or EVOO for short.
As Barcelona's Dr. Maria-Isabel Covas writes in her new paper, "Olive oil is the main fat in the Mediterranean diet. The wide range of anti-atherogenic [plaque-preventing/stabilizing] effects associated with olive oil consumption could contribute to explain the low rate of cardiovascular mortality found in Southern European Mediterranean countries, in comparison with other western countries, despite a high prevalence of CHD [coronary heart disease] factors” (Covas MI 2007).
By "...high prevalence of CHD [coronary heart disease] factors" she means the high smoking rates and diets full of pork, sausage, cheese, and white bread actually found among people in Mediterranean regions.
The monounsaturated "Scandinavian Diet”: More clues to the mystery
The fatty acid that predominates in olive oil—a monounsaturated one called oleic acid—is also one of the main fatty acids in the animal foods consumed widely in Western diets, such as poultry and pork.
Surprised? It gets better.
In a Swedish study published six years ago, comparing Swedish and Spanish women, the Spanish ladies clearly ate more fruit and vegetables than the Swedish women did... no big surprise there.
The shocker was that blood levels of oleic acid were higher in the Swedes than in women from Spain's Seville, and those levels correlated closely with the Swedes' meat intake (Chajes V et al 2001).
Clearly, monounsaturated oleic acid alone is not what gives olive oil its heart-healthy properties, or we'd all be talking about the wonders of the "Scandinavian Diet.”
So why, despite eating diets that are not very heart-healthy—aside, that is, from using olive oil in place of butter and corn or canola oil—do Mediterranean peoples enjoy markedly lower rates of heart disease?
The answer lies in olive oil… but not, as we've seen, for the monounsaturated reasons once thought… at least not the whole answer.
Mono fats form hearty foundation… but aren't enough
All grades of olive oil—which contain equal proportions of monounsaturated oleic acid—do six good things:
- Raise HDL ("good”) cholesterol levels
- Lower triglyceride levels
- Lower the ratio of total cholesterol to HDL cholesterol
- Reduce oxidation of LDL cholesterol*
- Lower blood pressure
- Reduce damage to DNA from free radicals
*Oxidation of LDL cholesterol by free radicals plays a key role in promoting cardiovascular disease. Using olive oil as your primary dietary fat fills LDL particles with oxidation-resistant monounsaturated oleic acid, instead of the polyunsaturated omega-6 fatty acids that predominate in other vegetable oils, like corn and safflower.
Until recently, these half-dozen beneficial effects had been attributed solely to monounsaturated fatty acids, which predominate only in olive oil and macadamia nut oil.
When in 2004 the US FDA began allowing olive oil labels to declare that eating about two tablespoons (23 g) of olive oil daily could reduce the risk of coronary heart disease, they specified that labels had to say that this was "…due to the monounsaturated fat (MUFA) in olive oil.”
But that notion's been clearly proven wrong.
In fact, extra virgin grade oil (EVOO)—the only kind with its antioxidants intact—appears substantially better for heart health, compared with "virgin” grade oil and especially with antioxidant-free "pure” grade, which can now simply be labeled "olive oil.”
That trial examined the effects of the three grades of olive oil—which have very different amounts of antioxidant phenols, ranging from none to lots (in EVOO)—on blood levels of triglycerides and cholesterol, and damage to blood lipids and arterial tissues from free oxygen radicals: so-called "oxidative stress”. (Covas MI, Nyyssonen K, et al 2006)
In the end, the high-phenol (Extra Virgin) olive oil outperformed the other two oils (Virgin and Pure grade) when it came to enhancing three factors helpful to cardiovascular health:
- Lowest ratio of total cholesterol "good” HDL cholesterol
- Biggest rise in HDL cholesterol
- Biggest drop in levels of oxidized LDL cholesterol
And other studies prove that the phenol antioxidants in EVOO—which are scarcer in Virgin grades and utterly absent from Pure grade oils—do wonders for the health and performance of the endothelial tissue that lines our arteries: a key factor in cardiac health.
All three oils reduced triglyceride levels to the same extent, which suggests that the monounsaturated oleic acid in all olive oils is largely responsible for this particular cardiovascular benefit.
You don't take huge amounts of EVOO to help your heart. As Dr. Covas says in her new evidence review, "The fact that phenolic compounds from olive oil are bioavailable… even from doses… lower than those reported as usual in the Mediterranean diet… reinforces their possible protective role...”
It looks like the actual diets of Italy, Greece, and Spain aren't much like what's described as "The Mediterranean Diet” …no matter how healthful this idealized version of Mediterranean reality has proven to be in many studies testing it.
And it's increasingly clear that EVOO is something of a magic bullet that counteracts what in reality are some otherwise nutritionally mediocre Mediterranean-region diets that happen, fortunately, to feature the world's heart-healthiest food oil very heavily.
- Covas MI. Olive oil and the cardiovascular system. Pharmacol Res. 2007 Jan 30; [Epub ahead of print]
- Chajes V, Elmstahl S, Martinez-Garcia C, Van Kappel AL, Bianchini F, Kaaks R, Riboli E. Comparison of fatty acid profile in plasma phospholipids in women from Granada (southern Spain) and Malmo (southern Sweden). Int J Vitam Nutr Res. 2001 Jul;71(4):237-42.
- van Kappel AL, Martinez-Garcia C, Elmstahl S, Steghens JP, Chajes V, Bianchini F, Kaaks R, Riboli E. Plasma carotenoids in relation to food consumption in Granada (southern Spain) and Malmo (southern Sweden). Int J Vitam Nutr Res. 2001 Mar;71(2):97-102.
- Covas MI, Nyyssonen K, Poulsen HE, Kaikkonen J, Zunft HJ, Kiesewetter H, Gaddi A, de la Torre R, Mursu J, Baumler H, Nascetti S, Salonen JT, Fito M, Virtanen J, Marrugat J, EUROLIVE Study Group. The effect of polyphenols in olive oil on heart disease risk factors: a randomized trial. Ann Intern Med. 2006 Sep 5;145(5):333-41.
- Covas MI, de la Torre K, Farre-Albaladejo M, Kaikkonen J, Fito M, Lopez-Sabater C, Pujadas-Bastardes MA, Joglar J, Weinbrenner T, Lamuela-Raventos RM, de la Torre R. Postprandial LDL phenolic content and LDL oxidation are modulated by olive oil phenolic compounds in humans. Free Radic Biol Med. 2006 Feb 15;40(4):608-16. Epub 2005 Oct 18.
- Marrugas J, Covas MI, Fito M, Schroder H, Miro-Casas E, Gimeno E, Lopez-Sabater MC, de la Torre R, Farre M; SOLOS Investigators. Effects of differing phenolic content in dietary olive oils on lipids and LDL oxidation--a randomized controlled trial. Eur J Nutr. 2004 Jun;43(3):140-7. Epub 2004 Jan 6.
- Weinbrenner T, Fito M, Farre Albaladejo M, Saez GT, Rijken P, Tormos C, Coolen S, De La Torre R, Covas MI. Bioavailability of phenolic compounds from olive oil and oxidative/antioxidant status at postprandial state in healthy humans. Drugs Exp Clin Res. 2004;30(5-6):207-12.
- Weinbrenner T, Fito M, de la Torre R, Saez GT, Rijken P, Tormos C, Coolen S, Albaladejo MF, Abanades S, Schroder H, Marrugat J, Covas MI. Olive oils high in phenolic compounds modulate oxidative/antioxidative status in men. J Nutr. 2004 Sep;134(9):2314-21.