The Mediterranean Diet

The term "Mediterranean diet" can be used to describe the eating pattern of at least 16 countries that border the Mediterranean Sea, which presents some difficulty in characterizing a Mediterranean diet. Research on the health benefits of a Mediterranean eating pattern date back to the 1950s with the "Seven Countries Study," which established the Mediterranean diet as a heart-healthy eating pattern based on the traditional foods and cooking styles of this part of the world.

Research on the Mediterranean diet has evolved and grown rapidly since the landmark 1950s study. Criteria used to define the Mediterranean diet has also evolved over the years. In 2021, based on findings from the Dietary Approaches and Health Outcomes scoping review, the Academy's Evidence Analysis Center conducted an umbrella review of the Mediterranean diet and cardiovascular disease risk factors. Commonalities for the definition of a Mediterranean diet in the studies examined were that they were high in whole grains, fruits, and vegetables, included legumes and olive oil with low to modest meat intake.

According to the sub-analysis, an eating pattern based on the characteristics of a Mediterranean diet compared to usual intake may decrease blood pressure in the general population and reduce weight, low-density lipoprotein cholesterol and systolic blood pressure in individuals with an elevated body mass index (Grade: Moderate B). There is also some research to suggest a Mediterranean diet may be more effective than other therapeutic diets in lowering triglycerides and LDL cholesterol in the general population, and individuals diagnosed with type 2 diabetes may benefit from improved dyslipidemia and glycemic control (Grade: Low C).

Widely reported research regarding the potential health benefits of a Mediterranean eating pattern is likely to influence some people to adopt some form of a Mediterranean diet. An article published in the Journal of the Academy of Nutrition and Dietetics in January of 2022 identified barriers and enablers to recommending or following a Mediterranean dietary pattern for patients in Australia being treated for coronary heart disease or type 2 diabetes. Fifty-seven clinicians were interviewed for the study and of those 13 were dietitians. Other clinicians included nurses, doctors, and physiotherapists.

Four major themes were identified as barriers and related to either the clinician, their perceptions about patients (e.g., lack of motivation), current practices for dietary consults, or were influenced by the organizational culture and its resources for patient education. Some of the clinician-centered barriers to recommending a Mediterranean diet included limited knowledge, variable understanding of the research and a lack of training and education. As a result, dietitians indicated pursuing independent learning or relying on colleagues for sharing of this information. The initiation of multidisciplinary case conferences, training by dietitians, and joint consults were additionally considered as being beneficial for the exchange of information across disciplines.

An enabler to implementing a Mediterranean diet from a clinician standpoint included an understanding of the science to support the connection between it and markers of cardiometabolic risk, which the project helps to inform. The influence of social determinants of health was also identified as a sub-theme with some clinicians having a perception that a Mediterranean diet was not applicable to every culture or that it would be cost prohibitive. Dietary advice tended to focus on single nutrients, such as lowering salt or fat intake, and clinicians who were not dietitians were more likely to discuss food restrictions rather than promoting healthful food choices or the significance of a dietary pattern.

The 2020-2025 Dietary Guidelines for Americans continues to recommend the Healthy Mediterranean-Style Dietary Pattern as one of several dietary patterns which can help promote health and reduce the risk of diet-related chronic disease. Although the Dietary Guidelines are intended for health promotion, they can be adapted to meet the needs of patients with chronic diseases and customized to accommodate personal and cultural food preferences.

Counseling the patient or client who wants to incorporate the Mediterranean diet into their lifestyle begins with collecting as much information as possible before the first encounter. This process can help determine how a patient's current intake compares to the Mediterranean dietary pattern. Registered dietitian nutritionists can then individualize their approach to help individuals who are motivated to make changes that incorporate characteristics of the Mediterranean diet into their eating plan, thereby helping to manage or reduce the risk of chronic disease.

References:

• Keys A. Seven Countries: A Multivariate Analysis of Death and Coronary Heart Disease. Cambridge, MA: Harvard University Press: 1980.
• Davis C, Bryan J, Hodgson J, Murphy K. Definition of the Mediterranean Diet; a Literature Review. Nutrients. 2015 Nov 5;7(11):9139-53.
• Academy of Nutrition and Dietetics Evidence Analysis Library. Dietary Approaches and Health Outcomes. Accessed May 2, 2022.
• Mayr HL, Kelly JT, Macdonald GA, Russell AW, Hickman IJ. Clinician Perspectives of Barriers and Enablers to Implementing the Mediterranean Dietary Pattern in Routine Care for Coronary Heart Disease and Type 2 Diabetes: A Qualitative Interview Study. J Acad Nutr Diet. 2022 Jan 31:S2212-2672(22)00043-0. Published online ahead of print January 31, 2022.
• US Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. Accessed April 25, 2021.