by Craig Weatherby and Linda Sparrow
The encouraging findings of a clinical trial from Naples, Italy indicate that a classic Mediterranean diet can improve heart risk factors and blood sugar control, and delay the need for drug therapy among overweight diabetics.
As the team led by Katherine Esposito wrote in the Annals of Internal Medicine, “Participants assigned to the Mediterranean-style diet lost more weight and experienced greater improvements in some glycemic [blood sugar] control and coronary risk measures than did those assigned to the low-fat diet.”
This finding should be welcome news to the nearly 24 million Americans—about one in 12 adults—diagnosed with diabetes.
And the results should be put to practical use, since healthcare costs for diabetes patients in the U.S. reach about $174 billion according to the American Diabetes Association, with drug treatments accounting for about $116 billion of that total.
Non-medical, lifestyle means of deterring diabetes and delaying the need for treatment could alleviate suffering and cut runaway health care costs.
The so-called “Mediterranean diet” studied by researchers and promoted by public health authorities is actually an idealized version of the eating patterns of rural people living on Greek’s Aegean Islands in the 1960’s. For more on this topic, search our newsletter archive for “Mediterranean.”
It’s not the only diet associated with reduced rates of heart disease and cancer, because some Asian diets also produce healthier, longer-lived people than the American diet does.
In fact, it appears that most any diet that favors fruits, vegetables, whole grains, legumes, and fish over refined grains, meat, and processed foods will be more healthful.
However, compared with East Asian cuisine, the Mediterranean diet appeals to more Americans, and has been more intensively studied.
And it features a cooking oil with unique attributes.
Unlike the vegetable oils used in Western and Asian cooking—corn, soy, sesame, safflower, sunflower (and canola to a lesser extent)—which are high in pro-inflammatory omega-6 fatty acids, the Mediterranean’s extra virgin olive oil is rich in benign monounsaturated fats and super-potent antioxidants.
For more about the benefits of extra virgin olive oil, search our newsletter archive for “extra virgin.”
Details of the Italian trial: Mediterranean diet vs. diabetes
The Italian study involved 215 overweight people who were newly diagnosed with type-2 diabetes.
Some were assigned to eat a low-fat diet, which capped the proportion of daily calories from fat at 30 percent. In American terms, this was not a particularly low-fat diet, since it only provided five percent fewer calories from fat, compared with the 35 percent of calories from fat found in the average American’s diet (USDA data).
The other participants were assigned to eat a Mediterranean diet, in which up to 50 percent of daily calories could come from fat.
After four years, 70 percent of those eating the low-fat diet required diabetic drug treatment designed to control blood sugar, while only 44 percent of those eating the Mediterranean diet needed drug treatment.
The Mediterranean diet also resulted in an average weight loss of 4.4 pounds and improvements in body mass index (BMI) among the people in that group.
The researchers speculated that olive oil—which replaced standard vegetable oils in the Mediterranean diet group—might be one reason for the reduced risk of developing pre-diabetic blood sugar problems.
Standard vegetable oils are high in omega-6 polyunsaturated fats, but olive oil has very few of those, and instead is high in monounsaturated fatty acids.
As the Italian team wrote, “Consumption of monounsaturated fatty acids is thought to increase insulin sensitivity, and this component of the diet might explain the favorable effect of the MED diet on the need for drug therapy.”
The Mediterranean ideal
The idealized Mediterranean diet studied in this and many other trials is high in beans and other legumes, whole grains, nuts, whole grain foods, fruits, fish, and olive oil, and is low in meat, dairy, and processed foods.
Compared with the standard American diet, the classic Mediterranean diet is richer in fiber, antioxidants, omega-3 fatty acids (from greens and fish), vitamins and minerals.
Some researchers have tried to define the Mediterranean diet in terms of its nutritional makeup, since that, more than any specific food, is the key to the eating plan’s health benefits.
Earlier this year, a Spanish team proposed that the diet should have a monounsaturated to saturated fatty acid ratio of 1.6 to 2.0 and 41 to 62 grams of daily dietary fiber (Saura-Calixto F, Goñi I 2009).
They also suggest a Mediterranean diet must be high in antioxidants and phytosterols, which help maintain cell health and lower cholesterol.
In addition to the most recent findings concerning diabetes, the idealized Mediterranean diet has been associated with longer life, and reduced risk of heart disease, and certain common cancers.
- Babio N, Bulló M, Salas-Salvadó J. Mediterranean diet and metabolic syndrome: the evidence. Public Health Nutr. 2009 Sep;12(9A):1607-17.
- Esposito K, Maiorino MI, Ciotola M, Di Palo C, Scognamiglio P, Gicchino M, Petrizzo M, Saccomanno F, Beneduce F, Ceriello A, Giugliano D. Effects of a Mediterranean-style diet on the need for antihyperglycemic drug therapy in patients with newly diagnosed type 2 diabetes: a randomized trial. Ann Intern Med. 2009 Sep 1; 151(5): 306-14.
- Jenkins DJ, Kendall CW, McKeown-Eyssen G, Josse RG, Silverberg J, Booth GL, Vidgen E, Josse AR, Nguyen TH, Corrigan S, Banach MS, Ares S, Mitchell S, Emam A, Augustin LS, Parker TL, Leiter LA. Effect of a low-glycemic index or a high-cereal fiber diet on type 2 diabetes: a randomized trial. JAMA. 2008 Dec 17; 300(23): 2742-53.
- Proietti AR, del Balzo V, Dernini S, Donini LM, Cannella C. [Mediterranean diet and prevention of non-communicable diseases: scientific evidences] Ann Ig. 2009 May-Jun;21(3):197-210. Italian.
- Saura-Calixto F, Goñi I. Definition of the Mediterranean diet based on bioactive compounds. Crit Rev Food Sci Nutr. 2009 Feb; 49(2): 145-52.
- United States Department of Agriculture (USDA). Profiling Food Consumption in America, Chapter 2. Accessed online at http://www.usda.gov/factbook/chapter2.htm