The enduring popularity of the Mediterranean diet is attributable to three things:
3. Health benefits
For our purposes today, I use “diet” to refer to the usual food and drink of a person, not a weight-loss program.
The scientist most responsible for the popularity of the diet, Ancel Keys, thought the heart-healthy aspects of the diet related to low saturated fat consumption. He also thought the lower blood cholesterol levels in Mediterranean populations (at least Italy and Greece) had something to do with it, too. Dietary saturated fat does tend to raise cholesterol levels.
Even if Keys was wrong about saturated fat and cholesterol levels being positively associated with heart disease, numerous studies (involving eight countries on three continents) strongly suggest that the Mediterranean diet is one of the healthiest around. See References below for the most recent studies.
Relatively strong evidence supports the Mediterranean diet’s association with:
■ increased lifespan
■ lower rates of cardiovascular disease such as heart attacks and strokes
■ lower rates of cancer (prostate, breast, uterus, colon)
■ lower rates of dementia
■ lower incidence of type 2 diabetes
Weaker supporting evidence links the Mediterranean diet with:
■ slowed progression of dementia
■ prevention of cutaneous melanoma
■ lower severity of type 2 diabetes, as judged by diabetic drug usage and fasting blood sugars
■ less risk of developing obesity
■ better blood pressure control in the elderly
■ improved weight loss and weight control in type 2 diabetics
■ improved control of asthma
■ reduced risk of developing diabetes after a heart attack
■ reduced risk of mild cognitive impairment
■ prolonged life of Alzheimer disease patients
■ lower rates and severity of chronic obstructive pulmonary disease
■ lower risk of gastric (stomach) cancer
■ less risk of macular degeneration
■ less Parkinsons disease
■ increased chance of pregnancy in women undergoing fertility treatment
■ reduced prevalence of metabolic syndrome (when supplemented with nuts)
■ lower incidence of asthma and allergy-like symptoms in children of women who followed the Mediterranean diet while pregnant
Did you notice that I used the word “association” in relating the Mediterranean diet to health outcomes? Association, of course, is not causation.
The way to prove that a particular diet is healthier is to take 20,000 similar young adults, randomize the individuals in an interventional study to eat one of two test diets for the next 60 years, monitoring them for the development of various diseases and death. Make sure they stay on the assigned test diet. Then you’d have an answer for that population and those two diets. Then you have to compare the winning diet to yet other diets. And a study done in Caucasians would not necessarily apply to Asians, Native Americans, Blacks, or Hispanics.
Now you begin to see why scientists tend to rely on observational rather than interventional diet studies.
I became quite interested in nutrition around the turn of the century as my patients asked me for dietary advice to help them lose weight and control or prevent various diseases. At that time, the Atkins diet, Mediterranean diet, and Dr. Dean Ornish’s vegetarian program for heart patients were all popular. And you couldn’t pick three programs with more differences! So I had my work cut out for me.
After much scientific literature review, I find the Mediterranean diet to be the healthiest for the general population. People with particular medical problems or ethnicities may do better on another diet. People with diabetes or prediabetes are probably better off with a carbohydrate-restricted diet, such as the Low-Carb Mediterranean Diet.
Dan Buettner makes a good argument for plant-based diets in his longevity book, The Blue Zones. The Mediterranean diet qualifies as plant-based.
What do you consider the overall healthiest diet, and why?
Sofi, Francesco, et al. Accruing evidence about benefits of adherence to the Mediterranean diet on health: an updated systematic review and meta-analysis. American Journal of Clinical Nutrition, ePub ahead of print, September 1, 2010. doi: 10.3945/ajcn.2010.29673
Buckland, Genevieve, et al. Adherence to a Mediterranean diet and risk of gastric adenocarcinoma within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort study. American Journal of Clinical Nutrition, December 9, 2009, epub ahead of print. doi: 10.3945/ajcn.2009.28209
Fortes, C., et al. A protective effect of the Mediterraenan diet for cutaneous melanoma. International Journal of Epidmiology, 37 (2008): 1,018-1,029.
Sofi, Francesco, et al. Adherence to Mediterranean diet and health status: Meta-analysis. British Medical Journal, 337; a1344. Published online September 11, 2008. doi:10.1136/bmj.a1344
Benetou, V., et al. Conformity to traditional Mediterranean diet and cancer incidence: the Greek EPIC cohort. British Journal of Cancer, 99 (2008): 191-195.
Mitrou, Panagiota N., et al. Mediterranean Dietary Pattern and Prediction of All-Cause Mortality in a US Population, Archives of Internal Medicine, 167 (2007): 2461-2468.
Feart, Catherine, et al. Adherence to a Mediterranean diet, cognitive decline, and risk of dementia. Journal of the American Medical Association, 302 (2009): 638-648.
Scarmeas, Nikolaos, et al. Physical activity, diet, and risk of Alzheimer Disease. Journal of the American Medical Association, 302 (2009): 627-637.
Scarmeas, Nikolaos, et al. Mediterranean Diet and Mild Cognitive Impairment. Archives of Neurology, 66 (2009): 216-225.
Scarmeas, N., et al. Mediterranean diet and Alzheimer disease mortality. Neurology, 69 (2007):1,084-1,093.
Fung, Teresa, et al. Mediterranean diet and incidence of and mortality from coronary heart disease and stroke in women. Circulation, 119 (2009): 1,093-1,100.
Mente, Andrew, et al. A Systematic Review of the Evidence Supporting a Causal Link Between Dietary Factors and Coronary Heart Disease. Archives of Internal Medicine, 169 (2009): 659-669.
Salas-Salvado, Jordi, et al. Effect of a Mediterranean Diet Supplemented With Nuts on Metabolic Syndrome Status: One-Year Results of the PREDIMED Randomized Trial. Archives of Internal Medicine, 168 (2008): 2,449-2,458.
Mozaffarian, Dariush, et al. Incidence of new-onset diabetes and impaired fasting glucose in patients with recent myocardial infarction and the effect of clinical and lifestyle risk factors. Lancet, 370 (2007) 667-675.
Esposito, Katherine, et al. Effects of a Mediterranean-style diet on the need for antihyperglycemic drug therapy in patients with newly diagnosed type 2 diabetes. Annals of Internal Medicine, 151 (2009): 306-314.
Shai, Iris, et al. Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat Diet. New England Journal of Medicine, 359 (2008): 229-241.
Martinez-Gonzalez, M.A., et al. Adherence to Mediterranean diet and risk of developing diabetes: prospective cohort study. British Medical Journal, BMJ,doi:10.1136/bmj.39561.501007.BE (published online May 29, 2008).
Trichopoulou, Antonia, et al. Anatomy of health effects of the Mediterranean diet: Greek EPIC prospective cohort study. British Medical Journal, 338 (2009): b2337. DOI: 10.1136/bmj.b2337.
Barros, R., et al. Adherence to the Mediterranean diet and fresh fruit intake are associated with improved asthma control. Allergy, vol. 63 (2008): 917-923.
Varraso, Raphaelle, et al. Prospective study of dietary patterns and chronic obstructive pulmonary disease among US men. Thorax, vol. 62, (2007): 786-791
6 responses to “Health Benefits of the Mediterranean Diet”
What have you observed anectdotally in your practice?
Is there a decent population of people willing to make the changes and stick with them? If so, do you notice improvements in the usual markers (bp, A1c, HDL/LDL, etc)?
And the $64 million question, how do physicians get reimbursed for it?
As your post indicates, there are far too many variables to say one particular diet is best for all people. I blogged about a follow up study to the famous “A – Z Weight Loss Study” published in JAMA in 2007 where, when averaged, all four groups of women lost weight on four different diets: Atkins, LEARN, Ornish and Zone (low carb dieters lost more, as is common in these studies).
But the authors noted that within each group of women there were those that lost significantly more and those that lost less (or even gained weight). This is a common finding in weight loss studies, and usually the participants are blamed for non-compliance or lying about food intake (i.e., being fat pigs who stuff their mouths when no one is looking.)
The follow up study, which I blogged about at http://goo.gl/VMCp0, tested some of the participants and re-assigned them to a diet based on some genetic markers that predicted they would do well on either a low fat or, conversely, on a low carb diet. The weight loss in the two follow up groups, sorted and assigned a diet based on their genetic makeup, was remarkable. The Wall Street Journal noted:
“In a study involving 133 overweight women, those with a genetic predisposition to benefit from a low-carbohydrate diet lost 2 1/2 times as much weight as those on the same diet without the predisposition. Similarly, women with a genetic makeup that favored a low-fat diet lost substantially more weight than women who curbed fat calories without low-fat genes. The women were followed for a year.”
A weight loss diet is not necessarily equal to a healthy diet, but I think that adherence to a particular way of eating may also be determined by our individual genetic make-up, rather than being a referendum on our strength of character. Someone should tell the personal trainers out there.
Finding a diet for your particular health risks is important; my high triglycerides and metabolic syndrome diagnosis meant that a low carb diet was in order. It worked, and I’m never hungry (even while losing 50 pounds over the last year).
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