Mediterranean diets and metabolic syndrome status in the PREDIMED randomized trial

This research is significant and establishes another important benefit of the Mediterranean diet, the likelihood to cause reversion of metabolic syndrome. Yet, it is suggested in this study that "...extra- virgin olive oil (which has anti-inflammatory properties)..."

I am writing to present studies to show that olive oil is no healthier than the saturated fat in beef, poultry, fish, or dairy. Given the saturated fat content of olive oil is often as much as 17% saturated fat, [lean, broiled beef is 15%], one has to question why olive oil is still considered anti-inflammatory or heart-healthy. I respectfully submit to the membership that olive oil is NOT an anti-inflammatory and instead that it is PRO-inflammatory and should be removed from Canadian recommendations pertaining to the Mediterranean diet. I present the following for your consideration. [Note: I am paraphrasing from the work of Dr. Caldwell B. Esselstyn, Jr., MD., Prevent and Reverse Heart Disease, with references cited from his text and lectures.]

The source of heart-healthy olive oil was The Lyon Diet Heart Study. It made headlines worldwide when its first-year results captured the imagination and created a free-for-all to dunk bread into olive oil, (liquid fat). In the first year of the study people on the Mediterranean diet had 50% or more lower incidence of heart related events including death. Granted, that is impressive! But, what failed to garner headlines was the frightening statistic revealed after four years: 25% on the Mediterranean diet had died or had a new cardiovascular event.

Since then, more studies have emerged demonstrating that the so- called "heart-healthy" oil claim is resting on a slippery slope.

Dr. Blankenhorn published a study demonstrating that, after a year, cardiovascular disease progression was undifferentiated between those consuming and not consuming monounsaturated fat. [D.H. Blankenhorn, R. Johnson, et al., Journal of the American medical Association, March 23, 1990: "The Influence of Diet on the Appearance of New Lesions in Human Coronary Arteries."]

Another study emerged and did point to some potentially heart-healthy benefits to consuming monounsaturated oil. HDLs can be increased and LDLs reduced. Perhaps, this is the source of belief in anti-inflammatory and heart-healthy benefits? Unfortunately, despite moving HDLs and LDLs in the right direction, autopsies revealed arterial damage occurred as much in the monounsaturated group as the saturated fat group. Why was that? A paradox may be explained in each of the hypotheses presented below regarding efflux and Apo-a1. [Lawrence L. Ruddel, John S. Parks, and Janet K. Sawyer, Arteriosclerosis, Thrombosis, and Vascular Biology, December 1995: "Compared with Dietary Monounsaturated and Saturated Fat, Polyunsaturated Fat Protects African Green Monkeys from Coronary Artery Arteriosclerosis."]

Then Japanese researchers revealed more negatives to the art of consuming monounsaturated fats. They demonstrated that monounsaturated fat raised blood sugar and triglycerides in animals. [N. Tsunoda, S. Ikemoto, M. Takahashi, et al. , Metabolism, June 1998: "High Monounsaturated Fat Diet-induced Obesity and Diabetes."]

Perhaps an effective demonstration of the immediate negative effects following the consumption of olive oil was the experiment conducted by R. Vogel and team. They demonstrated that the ability of the brachial artery in the forearm was hampered for hours following the consumption of olive oil. [R. Vogel, M Corretti, and G. Plotnick, Journal of the American College of Cardiology, 2000. "The Postprandial Effect of Components of the Mediterranean Diet on Endothelial Function"]

Recent research is demonstrating that it is not "How high is your HDL?" that matters. Rather, "How strong is your efflux capacity?" that matters most of all. "Cholesterol efflux capacity from macrophages, a metric of HDL function, has a strong inverse association with both carotid intima-media thickness and the likelihood of angiographic coronary artery disease, independently of the HDL cholesterol level. (Funded by the National Heart, Lung, and Blood Institute and others.)" [Source: "Cholesterol Efflux Capacity, High-Density Lipoprotein Function, and Atherosclerosis" by Khera, Cuchel, et al. N Engl J Med 2011; 364:127-135. http://www.nejm.org/doi/full/10.1056/NEJMoa1001689 ]

As my last reference, I am including a link to an abstract that discusses the role and potential damage that can be done to the APO-A1 protein. As you will see, evidence-based research points to the likelihood that once damaged APO-A1 converts to an antagonist that helps to amplify the damage done by the bad LDLs. [http://www.ncbi.nlm.nih.gov/pubmed/21304474.]

Summary: Though olive oil was once thought to be health-healthy, it was likely the benefits from increased consumption of vegetables and fruit groups that mitigated the immediate damage from consuming olive oil. In the long run, olive oil is not healthier than any other liquid fat. To put this in perspective, any increase to HDLs or lowering of LDLs may be of far less significance than strengthening efflux capacity by protecting Apo-a1 from damage. By consuming olive oil, in the long run, practitioners of the Mediterranean diet may be unwittingly accelerating the very thing they are most interested in protecting themselves from, undesirable cardiovascular events.

Yours truly, Ken Nanni

Conflict of Interest:

None declared

We thank Dr. Echeverria and colleagues for their insightful comments on PREDIMED study report showing a beneficial effect of the Mediterranean diet on metabolic syndrome.1 We agree with their contention that the Mediterranean diet could be more easily implemented and thus have a positive impact on metabolic syndrome and other chronic diseases in populations living in geographical areas sharing a Mediterranean ecosystem, such as California, Central Chile, South Africa, and South Australia, which, like the Mediterranean basin, are located near the 40th parallel in the corresponding hemisphere. In these areas, a similar warm climate allows farming typical Mediterranean foods such as olives, grapes, nuts, and a diversity of fruits and vegetables and producing two key components of the Mediterranean diet, olive oil and wine. Australian investigators have already used an a priori-defined Australian-style Mediterranean diet score,2 which is based on the scale of adherence to the Mediterranean diet of Trichopoulou and colleagues.3

Dr. Echeverria and colleagues cite as an example of consumption of the Mediterranean diet in Chile a 12-month behavioral intervention to promote this dietary pattern at the workplace.4 In that study a 14-point score of adherence to the Mediterranean diet adapted to Chilean dietary habits was used and increased from 4.8 at baseline to 7.4 at 12 months, which had a positive impact on metabolic syndrome status. The improvement in the score was due mainly to increased consumption of fruits and vegetables, whole grain bread, seafood, and canola and olive oil, and decreased meat consumption at lunchtime, when Mediterranean foods were made available at the canteen (nuts were not). The consumption of canola oil (not a Mediterranean culinary fat) increased from 0 to 21 ml/day, while olive oil increased only from 0 to 6 ml/day at lunch, and changes in wine intake at home were not reported. Thus, olive oil and nuts, two paradigmatic Mediterranean foods consumed abundantly in the PREDIMED study,1,5 were almost absent from this Chilean version of the Mediterranean diet, indicating that there is considerable room for improvement.

As in the case of the Australian Mediterranean diet,2 individuals adhering to its Chilean counterpart may be categorized as having a low score relative to those from Mediterranean populations.3,5 Due to the current stage of globalization and the availability of typical Mediterranean foods worldwide, spreading this dietary pattern beyond the 40th parallel countries is also feasible. However, an important aspect of the traditional Mediterranean diet should be considered: the quality of olive oil (mainly extra-virgin olive oil) and the quantity (up to 50 ml/day) used in Mediterranean countries, which facilitates the consumption of large amounts of vegetables.

The scientific evidence collected on the Mediterranean diet in epidemiologic studies3 and clinical trials such as PREDIMED1,5,6,7 suggests that it is a valuable nutrition education, health promotion and cost-effective disease prevention tool in Mediterranean countries. Long-term field trials are needed in countries outside the Mediterranean basin in order to demonstrate the transferability of the Mediterranean diet concept and confirm its beneficial health effects.

References

1. Babio N, Toledo E, Estruch R, et al. Mediterranean diets and metabolic syndrome status in the PREDIMED randomized trial. CMAJ. 2014;186:E649-57.

2. Trichopoulou A, Costacou T, Bamia C, Trichopoulos D. Adherence to a Mediterranean diet and survival in a Greek population. N Engl J Med 2003; 348:2599-608.

3. Gardener SL, Rainey-Smith SR, Barnes MB, et al. Dietary patterns and cognitive decline in an Australian study of ageing. Mol Psychiatry 2014 Jul 29. doi: 10.1038/mp.2014.79. [Epub ahead of print]

4. Leighton F, Polic G, Strobel P, et al. Health impact of Mediterranean diets in food at work. Public Health Nutr 2009;12:1635-43.

5. Estruch R, Ros E, Salas-Salvado J, et al. Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J Med 2013;368:1279-90. Erratum in: N Engl J Med 2014;370:886.

6. Ros E, Martinez-Gonzalez MA, Estruch R, Salas-Salvado J, Fito M, Martinez JA, Corella D. Mediterranean diet and cardiovascular health: Teachings of the PREDIMED study. Adv Nutr 2014;5:330S-6S.

7. Salas-Salvado J, Bullo M, Estruch R, et al. Prevention of diabetes with Mediterranean diets: a subgroup analysis of a randomized trial. Ann Intern Med 2014;160:1-10.

Conflict of Interest:

Ramon Estruch serves on the board of and has received lecture fees from the Research Foundation on Wine and Nutrition (FIVIN); he serves on the boards of the Beer and Health Foundation and the European Foundation for Alcohol Research; he has received lecture fees from Cerveceros de Espana and Sanofi-Aventis and grant support from Novartis. Emilio Ros serves on the board of and has received travel and grant support from the California Walnut Commission; he serves on the board of the Flora Foundation (Unilever); he serves on the board of and has received lecture fees from Roche; he serves on the board of and has received grant support from Amgen; he has received consulting fees from Damm and Abbott Laboratories; he has received consulting fees, lecture fees and grant support from Merck; he has received lecture fees from Danone, Pace, Astra Zeneca and Rottapharm; he has received lecture fees, grant support and payment for the development of educational presentations from Ferrer; he has received payment for the development of educational presentations from Recordati; and he has received grant support from Sanofi-Aventis, Takeda, Daiichi Sankyo, Nutrexpa, Feiraco, Unilever, and Karo Bio. Fernando Aros has received payment for the development of educational presentations from Menarini and Astra Zeneca.

Rosa Lamuela-Raventos serves on the board of and has received lecture fees from FIVIN; has received lecture fees from Cerveceros de Espa?a; and has received lecture fees and travel support from PepsiCo. Lluis Serra-Majem as follow-up: he is member of the Scientific Advisory Board and has received consulting fees and grant support from European Hyratation Institute; he has received lecture fees from International Nut council and travel support for conferences from Nestle. Xavier Pinto serves on the board of and has received grant support from the Residual Risk Reduction Initiative Foundation; he serves on the board of Omegafort; he serves the board of and has received payment for the development of educational presentations and grant support from Ferrer; he has received consulting fees from Abbott Laboratories; he has received lecture fees and grant support from Merck and Roche; he has received lecture fees from Danone and Esteve; he has received payment for the development of educational presentations from Menarini; and he has received grant support from Sanofi-Aventis, Kowa, Unilever, Boehringer Ingelheim, and Karo Bio. Jordi Salas-Salvado serves on the board of and has received grant support from the International Nut and Dried Fruit Council; he has received consulting fees from Danone; and he has received grant support from Eroski and Nestle. No other competing interests were declared.