Apr 7 2013

The Mediterranean diet: a delicious way to prevent heart disease?

In my April (first Sunday) Food Matters column for the San Francisco Chronicle, I catch up with the Mediterranean diet study first published online on February 25 (and widely publicized), and just now in print in the New England Journal of Medicine.

Q: I read about a study (New England Journal of Medicine, April 4) claiming that Mediterranean diets prevent heart attacks. Does this mean I can stop worrying about eating pasta?

A: That study, alas, was not about pasta. It wasn’t really about Mediterranean diets, either. Instead, it was about the benefits of supplementing healthy, largely vegetarian diets with olive oil or nuts.

We usually think of Mediterranean diets as offering lots of vegetables and fruit, some fish or poultry, small amounts of pasta, olive oil as the main fat, everything cooked wonderfully and accompanied by wine.

For years, studies of such diets have shown them to be associated with much lower rates of heart disease than are typically found in groups following “Western” diets. Studies of the effects of individual components of Mediterranean diets, however, have not always yielded such consistent results.

Used a control group

In the study you are referring to, investigators in Spain advised two groups of participants to follow a Mediterranean diet, but a control group to eat a low-fat diet. Advising people to eat in a certain way does not necessarily mean that they will. To make sure the diets differed, the investigators divided the Mediterranean diet advisees into two groups.

At no cost to participants, they gave one group a liter of extra virgin olive oil a week, with instructions to use at least 4 tablespoons daily. They gave the other Mediterranean diet group an ounce of mixed nuts a day to eat at least three times a week. They measured biomarkers in the participants’ blood to confirm that they really ate the supplements.

The results were impressive. Although there were no differences in overall mortality in nearly five years, the two supplemented-Mediterranean diet groups displayed about a 30 percent reduction in the risk of heart attacks and strokes as compared with the group advised to eat a low-fat diet.

But, because they did not find much change in the participants’ dietary patterns, the investigators concluded that the extra virgin olive oil and nut supplements must have been responsible for the observed health benefits.

What does the Mediterranean dietary pattern have to do with these results? Extra virgin olive oil and nuts are components of this pattern. Both contain “good” fats, largely unsaturated or polyunsaturated, and both are high in certain phenolic antioxidants.

These features have been recognized for decades. The Mediterranean diet came to public attention in America in the early 1990s as a result of efforts of the International Olive Oil Council, a trade group established by the United Nations.

The council recruited a group in Boston, Oldways Preservation and Exchange Trust, to promote olive oil to American chefs, nutritionists and food writers. If, they said, we ate diets similar to those followed by the Greeks and southern Italians since ancient times, we might also achieve similar levels of health and longevity.

The council and Oldways based this idea on the results of research initiated soon after World War II. In the late 1940s, Rockefeller University sent investigators to the island of Crete to find out why its people, although living in extreme poverty, were so healthy. Once past infancy, people on Crete displayed the highest longevity in the world, rivaled only by the Japanese.

Subsequent Seven Countries studies conducted by Ancel Keys and his colleagues appeared to confirm the health benefits of Mediterranean dietary patterns.

Olive oil, nuts critical

Olive oil or nuts seem critical to these benefits. Besides their fat and phenol content, both are wonderful to eat. Olive oil tastes good by itself and it makes other foods, particularly vegetables, taste delicious. Nuts enliven any dish. So research on Mediterranean diets brought good news. You could eat delicious food – and it would be good for you.

The Mediterranean diet took hold. In the early 1990s, you had to search hard for a decent bottle of extra virgin olive oil; now almost any supermarket carries several brands, many of high quality. Except during the sad, but blessedly brief, low-carb era, the Mediterranean diet became mainstream.

But let’s be clear about what the Mediterranean diet is and is not. It is a model of the largely plant-based dietary pattern recommended by health agencies in the United States and worldwide. It does not mean supersize bowls of macaroni smothered in cheese.

Olive oil and nuts, for all their virtues, are loaded with calories. The Spanish study’s 4 tablespoons provide 400 calories. An ounce of mixed nuts is about 200. Include them in your diet by all means, but most definitely in moderation.

I think the best reason for following a Mediterranean diet is that its foods are terrific to eat. Pasta, vegetables, a fish, some good bread, and a glass of wine? Sounds good to me, any time.

Marion Nestle is the author of “Why Calories Count: From Science to Politics,” as well as “Food Politics” and “What to Eat,” among other books. She is a professor in the nutrition, food studies and public health department at New York University, and blogs at foodpolitics.com. E-mail:food@sfchronicle.com. 

  • JR

    Given the growing body of evidence that refined carbohydrates are major contributors to diabetes and heart disease, it seems like a good idea to avoid the pasta (and bread). Sigh…

  • George H

    @JR,

    You can find plenty of whole grain pasta nowadays.

    About nuts, I find the most difficult part is control. 1 oz a day is good, but personally hard to do (not to eat more). I have had (raw) pecans and roasted them without any additional flavor. They taste so good that I feel I have I barely had any even after a cup (about 4 ounces). The only way I can control myself in front of nuts is not to have any in the first place. And I have thought I have pretty good self control in most of my diets.

    So for any foods, pasta or nuts, good or bad, the first and most important thing is self control. That is, everything in moderation. A lot harder to do than one thinks.

  • http://www.thehealthyeatingguide.com/ Scott @ The Healthy Eating Guide

    Olive oil is a staple of my diet but I try and eat little to not refined carbs. This has been the best approach for me personally to achieve my health goals and maintain the weight I want to be at. Clearly there’s now a mountain of evidence supporting the benefits of mono fat from sources like olive oil and nuts.

    But my question for you Marion is what’s your stance on polyunsaturated fats? I constantly get comments on my website from people who tout all vegetable oils other than coconut oil and olive oil as poison because of the PUFAs. But I haven’t seen much credible evidence to suggest polyunsaturated fats are bad for you. I’d be interested to get your take.

  • http://myheartsisters.org Carolyn Thomas

    Thanks for this reminder about olive oil, Marion. I sometimes have trouble getting four tablespoons in on any given day (I like my salads without any salad dressing generally) so am always looking for ways to incorporate that ‘good’ olive oil. My favourite: in a small bowl with balsamic vinegar as a butter-substitute for dipping crusty olive bread (but the danger in that is that I could go through a lot of delicious bread carbs just mopping up those four tablespoons!)

  • http://www.olivetomato.com Elena Paravantes, RD

    Marion, Thank you for your insightful article. I’m a Greek-American Nutritionist and Writer, specialized on the Greek Diet. I grew up on a traditional Greek-Mediterranean diet and still eat this way, all cooking and most baking was done with olive oil, even most desserts. So, I share these experiences with my readers not only from a personal perspective but also a professional one. Olive oil in the context of a Mediterranean diet will not result in weight gain (even at 4 T a day), we have to remember that most meals consisted of vegetables, so the total caloric value of the meal was still pretty low even with the olive oil. Another unique aspect of the diet (not very known) is that Greeks fasted for almost 200 days a year, eliminating all animal products (with the exception of some seafood), and following a diet based on vegetables, legumes, olive oil, olives, bread, barley rusks (dakos), nuts and fruit.

  • http://anaboliccooking4u.com Swati

    Olive oil is rich in vitamins A, B1, B2, C, D, E and other valuable nutrients. Olive oil has a high concentration of monounsaturated fatty acids, which studies show promote “good” cholesterol (HDL) while lowering “bad” cholesterol (LDL). It contains antioxidants, which many believe help protect the body from cancer.

    But to get best results use only olive oil that is labeled “extra virgin”. It comes from the first pressing of the olives and is considered the best oil. It is extracted without using heat (a cold press) or chemicals. Extra virgin olive oil supplies the best flavor and is green in color.

  • http://arthritishelper.org/ Sarah M

    It is good thing to know that the Mediterranean diet could prevent heart attack since many people experience this situation. I like vegetarian diets with olive oil or nuts because it is very healthy and nutritious. Perhaps I should take more salad and vegetables with olive oil as a dressing so that I could benefit from this study too. Thanks for sharing the informative article.

  • http://photografix.pro Eric B

    I wonder what results they would find if they examined sugar intake as well? (specifically added sugar).

  • http://www.howcookingworks.com Dan

    I think something people need to realize is most of the common olive oil we have in our supermarkets is adulterated, processed, and potentially blended with other oils lowering their benefits as documented in

    http://www.amazon.com/Extra-Virginity-Sublime-Scandalous-World/dp/0393070212

    If you go to an olive oil tasting store and taste it versus what you get in the market, it is a world of difference.

  • http://www.nutritionprescription.biz Michele Jacobson

    Yes, it’s so important to make certain that what you’re eating is actually olive oil, and not a blend of inferior oils. The very best way to do this is to read the label and make sure that your oil comes from a single source — whether it’s Spain, Italy, California, etc. I once purchased an organic California brand, only to arrive home and find that it was actually made from a blend from a number of Mediterranean countries! This is how most of the adulteration occurs: mixing inferior, and often not even olive, oils.

    Ms. Nestle, when researching my book I found it fascinating to read about the theory that the Mediterranean regions’ proximity to direct sunlight had an effect on higher levels of vitamin D production in the body, and this was also a contributing factor to the healthfulness (specifically, decreased mortality from CHD) of the regions inhabitants. As with the French Paradox, the Mediterranean diet is not diet alone, but a complete lifestyle, including the fast days, mentioned above, hard work ethic, etc.

    Michele Jacobson
    http://www.nutritionprescription.biz

  • ETaddison

    Sounds all swell and all.

    Except, as Marion pointed out, there was no difference in mortality. People on the wonderful diet didn’t live any longer. So if there was less heart disease, there must have been more of something else.

    Also, a 30% reduction in heart disease is a little misleading.

    What it means is, precisely, is that if say, 1 out 100 people eating the ‘wrong’ diet had incidents of disease, then 0.7 of out 100 people eating the ‘right’ diet had incidents.

    That’s a 30% decrease. But not quite as earth-shattering as you’d read in the news.

  • http://treadmillreviewcentral.com Timothy R

    I don’t think that it’s necessary to totally avoid pasta, especially if you are following the Mediterranean diet fairly strictly. I think you can easily substitute whole grain pasta (I did and I grew up eating Italian food at home and am very picky about it) for the processed stuff and it makes a big difference. Not to mention, if you are adding some kind of exercise regimen to your diet, you are going to need those carbs anyway, so I say enjoy the pasta, moderately of course!

  • http://tinnitusmiracleremedy.com Franko

    I agree with Timothy about the whole grain pasta. It takes a little time to get used to it, but now I actually prefer it to regular spaghetti. You don’t have to give up the stuff you really like to eat to be healthy, just try to follow a diet the best you can and give yourself a little leeway to eat things that you enjoy.

  • Michael Bulger

    ETaddison, there’s another way to look at a 30% reduction. As the study says, they found a reduction of approx. 3 cardiovascular events per 1000 (-30%). If we add the total numbers of heart attacks and strokes per year in the US (as reported by the CDC) we have 1.51 million. A 30% reduction of that figure would equal 453,000 fewer cardiovascular events.

    Saying that sounds swell would be quite an understatement. It would be a huge improvement in morbidity, save billions of dollars, and spare millions of people grief and anguish.

  • http://www.fatlossdietreview.org Sean

    Pasta is part of the true Mediterranean diet so I think it can have a place if you choose to eat it in the right way. However, I agree that the main beneficial parts of this diet are the veges, olive oil (and lots of it) and nuts. Thanks for the post.

  • http://www.english-to-go.com Kirsty Stewart

    For teachers out there interested in looking at the Mediterranean diet and nutrition, English-to-go.com’s latest free reading lesson is based on a Reuters article reporting the results of the Spanish study Find it at http://www.english-to-go.com/english/free_lesson.cfm
    Title of lesson: A Healthy Diet?
    Topic: A Mediterranean diet high in olive oil, nuts, fish and fresh fruits and vegetables may help prevent heart disease and strokes, says a large study from Spain.

  • Tim

    @JR: True, you should proably skip the refined wheat bread. However, pasta and pasta, even if made from white flour, are two very different foods. If cooked al dente, like the Italians prefer, it has a much lower glycemid load than pasta cooked to american-style pulp. The reason is that much of the starch in al dente pasta is too firm for the disgestive enzymes to break down, thus is becomes “resistant starch” which has properties similar to fiber.

  • brainmatters

    It cannot be stated often enough (and contrary to many of the comments here and elsewhere) that we are talking a LITTLE BIT of olive oil not “plenty of it” and “high in olive oil”. Four tablespoons is generous and may be fine for a younger male, but one to two tablespoons is plenty for the rest of us. As mentioned by the first comment, nuts also must be rationed and this can be difficult–they are easy to munch on and 1 or 2 oz isn’t very much. The foundation of the Med. diet is VEGETABLES-drizzled with olive oil or sprinkled with nuts, not gobs of olive oil and handfuls of nuts.

  • http://www.olivetomato.com Elena Paravantes, RD

    @brainmatters Regarding the amount of olive oil, the Mediterranean diet as was based on Greek diet, Cretan diet and Southern Italian diet was not vegetables “drizzled” with olive oil, but rather a good amount of olive oil was used, and the vegetables were cooked in the olive oil. In Greek cuisine there is even a whole category of dishes named “lathera” which means “cooked in oil”. You should actually see the olive oil among the vegetables after they are cooked. The meal as a whole had a moderate caloric value, because all you ate were vegetables cooked in olive oil, bread and cheese. The average consumption of olive oil in Greece ranges from about 20 to 30 liters a year per person, this corresponds to about 4 T a day on average. I remember seeing all these Greek women (including my grandmothers) pouring all this oil in the pot. But we need to remember that this was pretty much their source of fat (apart from some in the cheese and yogurt). I agree that you can’t start adding tons of olive oil in your diet and expect miracles, but within the context of the Mediterranean diet a good amount of olive is part of the plan. The Mediterranean diet is not a low-fat diet, trying to make it low-fat defeats the purpose.

  • http://www.youtube.com/watch?v=D7dGAbUhFMQ Ethan

    Great Post! Very informative. Never knew so many good stuffs about olive oil. Keep on writing this kind of great articles.