Mediterranean Diet: Better, Not Best?
Editor's Note: The author is Director of Nutrition at the Pritikin Longevity Center in Miami, Florida.
Mediterranean Diet Better Than Typical American Diet
In light of the recent media attention on the Mediterranean diet,[1] you may find yourself fielding lots of questions from patients about which diet they should follow. Right now, we cannot say which diet is best because we still need rigorous studies of all of the popular diets that physicians routinely recommend to their patients. Moreover, we cannot unequivocally recommend the Mediterranean diet on the basis of the recently published study because this study was seriously flawed.
One major problem with the study was that the "low-fat" diet being used to compare against the Mediterranean diet was not, in fact, low in fats. The participants in this group started out with a diet that averaged 39% fat, and during the study period they decreased fat intake to just 37%.
Nor was this so-called low-fat diet a healthy, well-designed regimen. Many of the foods eaten by participants were artery-damaging foods such as red meat, commercially baked goods full of refined flour and fat, sugary sodas, and low-fat cheeses. (Though called "low-fat," these cheeses typically get 35% to 60% of their calories from fat.)
Moreover, the "low-fat" diet excluded an important food proven to protect against heart disease: omega 3-rich fish. This category of food is included in many healthy low-fat-diet plans.
The bottom line is that the study authors were not really comparing a Mediterranean diet with a nutritious low-fat diet. It would be much more accurate to say that they were comparing a Mediterranean diet with a typical American-style diet. But it did not do justice to a well-constructed low-fat diet.
Healthy "Low-Fat" Diets
A substantial body of research exists that has documented the heart-healthy benefits of 2 well-known low-fat diets, Pritikin and Ornish. In fact, the data are so strong that Medicare now covers cardiac rehabilitation programs based on the Pritikin and Ornish plans for people with a history of cardiovascular disease.[2] Both programs also include exercise and lifestyle-change components.
The Ornish Program has been proven to regress heart disease,[3,4] and the Pritikin Program has been proven to significantly reduce many modifiable risk factors for cardiovascular disease, including low-density lipoprotein (LDL) cholesterol, triglycerides, blood glucose, hypertension, inflammatory markers such as C-reactive protein, and excess weight/obesity.[5-7]
Both programs recommend an eating plan with about 10% to 15% of calories coming from fat, and both emphasize hearty consumption of fruits, vegetables, whole grains, and legumes such as beans. The Ornish Program is completely vegetarian, whereas the Pritikin Program allows up to 4 oz of animal protein daily, such as omega-3-rich fatty fish, skinless white poultry, or lean meat such as bison.
Both of these programs are a far cry from the "low-fat" diets of the 1980s and 1990s, many of which were anything but healthy. Often, the "low-fat” and "fat-free" products people were eating (remember "fat-free" cookies?) were essentially junk food themselves -- very high in sugar, salt, and/or refined white flour.
Low-fat plans such as Pritikin and Ornish, by contrast, focus on real food -- whole, minimally processed, naturally fiber-rich foods that, as Michael Pollan wrote in his superb book In Defense of Food, "are foods our great grandmothers would have recognized as food."
Another low-fat diet that has proven to be particularly beneficial for blood pressure control is the DASH (Dietary Approaches to Stop Hypertension) diet. Several studies funded by the National Institutes of Health (NIH) have found that the DASH diet lowers blood pressure as well as or better than medications. DASH also promotes menus that are high in fruits, vegetables, whole grains, and beans; low in fats, salt, red meats, and sweets; and moderate in fish, poultry, nuts, and low-fat or nonfat dairy foods.
In one study, NIH researchers found that 8 weeks of following the DASH regimen resulted in reductions in blood pressure in all groups of men and women studied.[8] Even those who started with a normal blood pressure (systolic pressure < 120 mm Hg) saw improvements. The biggest reductions in blood pressure were observed in the individuals who were hypertensive (systolic pressure >140 mm Hg), emphasizing the fact that diet is a major factor in determining blood pressure in most hypertensive patients.
In another DASH study, 3 groups of people followed the diet but took in varying levels of sodium (3300 mg, 2400 mg, or 1500 mg per day). The researchers found that the biggest drops in blood pressure occurred in the group on the 1500 mg/day diet.[9]
Life Lessons
After nearly a decade of teaching healthy eating at the Pritikin Longevity Center, I can say with certainty that people can change. They really can revamp their behaviors and live better, healthier lives. But it takes much more, unfortunately, than simply handing them a diet pamphlet. What works is a solid education in several key skills for healthy living: classes in grocery shopping, reading food labels, cooking, and dining out healthfully. In addition, we provide classes that teach why these skills are so vital and how they benefit the body.
What matters, too, is taking time away from what I call the "American assault on our taste buds" -- a week or more spent eating foods that are completely free of salt, sugar, and grease, so that our palates have a chance to rediscover the good flavors of good food.
If, as a nation, we can institute educational programs like these, we can begin to empty our hospitals of patients needing angioplasties or coronary bypass surgeries; we can lighten the load of nursing facilities filled with people stricken with diabetic- and cardiovascular-related strokes, kidney failure, and amputations.
We know that the Mediterranean diet is better than the typical American diet. We also know that healthy, well-designed low-fat diets are better than the typical American diet. We need more research -- rigorous, randomized trials -- to identify not only the best diets but also the best ways to teach these diets.
In doing so, we can achieve real change across America, change that can not only curtail the staggering economic costs of chronic disease but also help people feel better and live better.
References
Estruch R, Ros E, Salas-Salvadó J, et al. Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J Med. 2013;DOI:10.1056/NEJMoa200303.
[No authors listed] Ornish, Pritikin get Medicare okay for cardiac rehab. Harv Heart Lett. 2010;21:7.
Ornish D, Brown SE, Scherwitz LW, et al. Can lifestyle changes reverse coronary heart disease? The Lifestyle Heart Trial. Lancet. 1990;336:129-133. Abstract
Chainani-Wu N, Weidner G, Purnell DM, et al. Changes in emerging cardiac biomarkers after an intensive lifestyle intervention. Am J Cardiol. 2011;108:498-507. Abstract
Barnard RJ. Effects of life-style modification on serum lipids. Arch Intern Med. 1991;151:1389-1394. Abstract
Sullivan S, Samuel S. Effect of short-term Pritikin diet therapy on the metabolic syndrome. J Cardiometab Syndr. 2006;1:308-312. Abstract
Wegge JK, Roberts CK, Ngo TH, Barnard RJ. Effect of diet and exercise intervention on inflammatory and adhesion molecules in postmenopausal women on hormone replacement therapy and at risk for coronary artery disease. Metabolism. 2004;53:377-381. Abstract
Appel LJ, Moore TJ, Obarzanek E, et al. A clinical trial of the effects of dietary patterns on blood pressure. DASH Collaborative Research Group. N Engl J Med. 1997;336:1117-1124. Abstract
Sacks FM, Svetkey LP, Vollmer WM, et al. Effects on blood pressure of reduced dietary sodium and the Dietary Approaches to Stop Hypertension (DASH) diet. DASH-Sodium Collaborative Research Group. N Engl J Med. 2001;344:3-10. Abstract
Medscape Diabetes & Endocrinology © 2013 WebMD, LLC
*****************************************
Evidence Is Compelling' on Mediterranean Diet
Mediterranean Diet Study
Hello. I am Dr. Eric Topol, Editor-in-Chief of Medscape. I am thrilled to be the new editor-in-chief; this is an extraordinary way for information to be disseminated to the medical community, and I am hoping to contribute with all the staff and our physician colleagues working around the globe to take Medscape to an "über level."
In this brief segment today, I will talk about the Mediterranean diet study. This is a study that was published in the February 25 New England Journal of Medicine.[1] I will try to get some commentary, either from myself or other colleagues, about really important studies, and I believe that this is one of them.
We don't talk enough about diet in medicine, but this is the largest randomized trial to date. The Mediterranean diet has been studied previously in randomized trials but not in a trial as large as this. It is fascinating that this was a study of more than 7400 individuals who were randomly assigned to 3 different diets. Two were Mediterranean diets enriched with either extra-virgin olive oil or nuts and other Mediterranean foods, both including more than 7 glasses of wine per week. The control diet was a low-fat diet, which some people have argued is not an ideal control. There was very good compliance with the diets in this large number of people for many years. The primary endpoint was death, heart attack, or stroke. There was a very important significant reduction of this cluster endpoint in the Mediterranean diet groups. Particularly noteworthy, even by itself, was the reduction in stroke.
Clinical Impact of the Mediterranean Diet Study
We now have dietary evidence that is fairly compelling. The absolute size reduction was not large, but the fact that the Mediterranean diets tested in this trial had such a positive impact gives us some anchoring about a diet that does lower critical cardiovascular endpoints. For many years, there has been discussion about this low-fat diet and whether it had a meaningful clinical impact. At one point, the Mediterranean diet was very much supported by the American Heart Association and other organizations. Now we see that it appears to be superior. The trial has had criticism, particularly honing in on the low-fat control arm of the study, but nonetheless, the evidence is compelling.
Why is this trial unique? It was funded by the Spanish government. This is a country that isn't known these days for having extraordinary resources to fund research, but the government of Spain got behind an important trial, perhaps the most impressive diet-randomized trial that has been performed. We have to give a lot of credit to them, because this trial was done with that level of funding and with superb investigators throughout the country of Spain, and it makes a lasting contribution. We are always in search of more information about what we eat, and this is welcome. It is particularly nice to know that you can have 7 glasses of wine or more each week and it might have a favorable effect.
We will be trying to highlight similar studies that are interesting, taking us across the whole spectrum of diagnostics, medical devices, genomics, wireless medicine, and topics such as diet and nutrition, to broaden some of the special coverage that we have at Medscape. Thanks very much for your attention.
References
Estruch R, Ros E, Salas-Salvadó J, et al. Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J Med. 2013 February 25. [Epub ahead of print]. http://www.nejm.org/doi/full/10.1056/NEJMoa1200303 Accessed March 6, 2013.
Medscape Internal Medicine © 2013 WebMD,
沒有留言:
張貼留言