Mined Terrain

The bottom line is that PREDIMED showed: If olive oil, then extra virgin. Extra virgin olive oil is produced by pressing olive paste, whereas “pure,” “regular,” and “light” olive oils are further processed, causing more of the original phytonutrients to be lost. The participants who were randomized to take extra virgin olive oil instead of processed olive oil not only suffered strokes less often, but also improved their cognitive abilities, developed atrial fibrillation, peripheral arterial occlusive disease, diabetes, diabetic retinopathy (vision loss), mild cognitive impairment, and breast cancer significantly less often. This may be because extra virgin olive oil does not seem to trigger the same rise in inflammatory markers as regular (i.e., refined) olive oil; it may also reduce oxidative stress better, presumably because more anti-inflammatory and antioxidant olive components are extracted. In addition, potentially toxic chemical contaminants form when processed oils are deodorized, for example 3-MCPD (3-monochloropropane-1,2-diol).

Regular olive oil contains up to 25 times more 3-MCPD than extra virgin olive oil. This makes it possible to distinguish among the different degrees of processing of olive oil. If a bottle is labeled “extra virgin olive oil” and still contains a lot of 3-MCPD, that means it has been diluted with refined olive oil. The fact that it is easy to do and hard to detect, that it can earn a lot of money, and that no one monitors it, tempts fraud involving extra virgin olive oil. How far does it go?

Of 88 bottles purchased in California that, according to the label, contained extra virgin olive oil, tests showed that this was actually true for only 33. Does it matter whether you stick to the best-selling imported brands like Colavita, Star, Bertolli, Filippo Berio, or Pompeian? No. An incredible 73 percent of these extra virgin olive oil samples failed. Only one in four was genuine, and not a single bestseller brand had even half of its samples pass the test. So even if you want to switch to extra virgin olive oil, it isn’t that easy.

The Lyon Diet Heart Study

Our understanding of the Mediterranean diet is limited by the number and quality of the available scientific research studies on this topic. Ironically, we may have more meta-analyses or systematic reviews on the Mediterranean diet and cardiovascular health than there are original studies in the first place. And most of these reviews are flawed because they use statistical methods that are unsuitable for combining study results.

It doesn’t help that some studies use up to 34 different scoring systems for the Mediterranean diet. For example, some studies awarded points for eating potatoes or subtracted points for eating eggs, while others considered neither. Most counted olive oil and nuts as characteristic components of the Mediterranean diet, which led to the criticism that the research was a conspiracy of disguised commercial interests of “Big Fat”; in fact, the vast majority of Mediterranean diet studies were financed not with private but with public funds. Of course, that does not prevent questionable work from being published. Just think of the “Indo-Mediterranean Experiment,” now fallen into disrepute for containing at least “gross errors,” because the researcher demonstrably “either invented or falsified data.” When he was asked to produce his original records, he refused on the grounds that they had been “eaten by termites.”

A famous trial of the Mediterranean way of eating that has stood the test of time is the Lyon Diet Heart Study: About 600 people, all of whom had already suffered a heart attack, were randomized into two groups. The control group received no dietary advice beyond their doctors’ instructions; the other group was to follow, as much as possible, a diet similar to the Mediterranean diet, supplemented by a canola oil spread. This provided participants with the plant-based omega-3 fatty acids they would have consumed with foods like walnuts if they had lived on a Greek island in the 1950s. Canola oil also lowers LDL cholesterol better than olive oil, and unlike olive oil, canola oil has no negative impact on arterial function.

The Mediterranean group took some of the dietary recommendations to heart. The participants ate more bread and fruit, while eating less butter, cream, processed meat, and meat in general. Otherwise, they changed nothing substantial, such as with wine, olive oil, or fish. So they ate fewer saturated fatty acids and cholesterol and increased their intake of plant-based omega-3 fatty acids, but otherwise did not change much. Nevertheless, after four years it was found that 44 participants in the control group had suffered a second heart attack; some had died from it. In the group with the modified diet, there had been only 14 heart attacks. The Mediterranean diet group reduced its 4 percent annual probability of suffering a heart attack to 1 percent.

Cynics might now object that although fewer people died or became ill in this group, the Mediterranean diet still further fueled the heart disease—so much so that 14 participants suffered another heart attack during the diet. There was a considerable drop in heart attack numbers, but of course in an ideal scenario we would want a diet that prevents heart disease altogether or even reverses it.

Dr. Caldwell Esselstyn and his colleagues at the Cleveland Clinic published a case series of 198 consecutive patients with severe cardiovascular disease who had been advised to eat only a whole-food, plant-based diet. Of these 198, 177 adhered to this way of eating in the long term; the other 21 did not. This created a natural experiment. What happened to the disobedient 21? Over the next roughly four years, more than half of them suffered a fatal heart attack or required angioplasty or a heart transplant. Of the 177 participants, by contrast, who had adhered to the plant-based diet over the same period, only one had a major heart attack as a result of progressive cardiovascular disease—0.6 percent compared to 62 percent in the disobedient group, a 100-fold risk reduction.

Dr. Esselstyn’s trial was not randomized, so it cannot be directly compared to the Lyon study. In addition, Dr. Esselstyn had highly motivated patients. Not everyone is willing to completely change their diet, not even when it is literally a matter of life and death. In that case, it is better to adhere more closely to the Mediterranean diet than to change nothing at all, because it reduces the risk of another heart attack by about two thirds. It would be better to achieve a 99 percent reduction if Esselstyn’s results were replicated in a controlled trial, but even a 70 percent lowering of risk would save countless lives every year. “Even if the results seem too good to be true,” wrote the director of the Harvard Program in Cardiovascular Epidemiology, “given the 20-fold or even greater differences between countries in the number of heart diseases, such results from changing diet are entirely plausible.”

The Okinawa Diet

To reduce the risk of chronic diseases, the American dietary guidelines recommend nutrient-dense but lower-calorie meals or snacks. By that measure, vegetables are the healthiest food in the world because, relative to calories, they contain the most nutrients. What would happen if you made vegetables the centerpiece of your diet, as the Japanese on Okinawa traditionally do? You would then belong to the world’s longest-lived people. (And yes, a validation study confirmed that there are many genuine 100-year-olds there.)