Mediterranean Diet


Definition/Introduction

Mediterranean diet is a generic term used to describe the dietary pattern of individuals living in the countries along the coast of the Mediterranean Sea, including Greece, Italy, southern France, Crete, Spain, and parts of the middle east. This article will utilize the Mediterranean diet in a broad sense, from the time of its initial rise pre-globalization to its use today. Before large-scale trade became available in the 1950s, people would eat what was available to them based on their geography, creating a seasonal variability for most. The Mediterranian diet is primarily a plant-based diet with the contributions from animal-based products being comprised of fish and poultry with a limited quantity of dairy products. While the modern version of the diet utilizes a higher proportion of red meat and processed foods, the diet's primary focus remains the same - plant-based with healthy fats. 

The food choices in the Mediterranian diet are comprised mainly of green leafy vegetables with a variety of legumes, nuts (e.g., walnuts, almonds, pistachios), fresh fruits, and whole grains also included. As the Mediterranean region is a significant producer of olive oil, this is also a staple in the diet. Olive oil is a monounsaturated fat containing alpha-linoleic acid, an omega-3 essential fatty acid, which has been indicated to provide a cardioprotective benefit.[1] The reduction of risk factors[2][3][4] is believed to be the major contributor to the reduction in cardiovascular disease seen in those who adhere to the Mediterranian diet. Fish and other animals of the sea provide a great source of other omega fatty acids and are another predominant reason for the cardioprotective nature.[5] Another important element to acknowledge is the consumption of wine in moderation (specifically red), which has been suggested to provide multiple metabolic benefits. The most reproducible benefit appears to be in lipid metabolism, believed to be attributable to ethanol, but its microconstituents also may play important roles in hemostasis and inflammation.[6]

Issues of Concern

The requirement for strict adherence to this diet for the best preventative effects is not practical for most people in today's world. Therefore, it is of the utmost importance to realize benefits appear to be significantly diminished when adherence occurs in an episodic nature or when only certain parts of the diet are followed.[5] Recognizing the role the intestinal microbiome plays in overall immune, cardiovascular, endocrine, and, the more obvious, gastrointestinal system functions, and the realization that the microbiome may change in as few as four days aids in highlighting the importance of adherence to the diet.[7][8] It is also imperative to recognize that there should be some component of physical activity and that, as with all diets, moderation in consumption also plays an important role in the overall efficacy of the Mediterranian diet. The inter-individual variation between taste preferences is acknowledged, i.e., preferring salty over sweet, and produces a wide variation in adherence.[9] 

While most studies suggest improvements in cardiovascular risk factors, the quality of evidence for these studies is felt by some to be only low to moderate.[10] Additionally, some studies seem to reveal no improvement in the measured values of inflammatory markers or metabolic risk factors.[11] It is also noted that the majority of published studies focus on adult subjects, and additional studies in other age groups would be beneficial. However, arguably the most significant barrier to adherence would be that recommendations for what exactly comprises a Mediterranean diet are not homogenous between studies. 

Clinical Significance

The preventative benefits of the Mediterranean diet have been demonstrated throughout both observational and randomized control trials. The landmark study for support was the 'Seven Countries Study,' which suggested a significantly decreased risk for and lower rates of cardiovascular disease overall in those adhering to the Mediterranian diet, and other studies have since produced similar results.[12][13] There have also been several studies to demonstrate a decreased risk for members of certain subgroups, such as patients with non-alcoholic fatty liver disease, those with familial heterozygous hypercholesterolemia (HFH), and patients with recent myocardial infarction.[14][15][16] These findings would suggest the benefits could be further extrapolated, as well. Mediterranean diet has been recognized to improve glycemic control and insulin resistance in patients with diabetes with a high risk of cardiovascular disease.[17] There have also been several studies demonstrating a decrease in early vascular aging.[18] Given the above protective factors, it is likely the benefits of the Mediterranean diet can be extrapolated to include individuals with metabolic syndrome.[19] There is also a suggestion regarding reducing the development of other health issues, including osteoporosis, inflammatory bowel disease, preterm birth, macular degeneration, kidney stones, dry eye, cancers (breast and colorectal), neurocognitive disorders, and select patients with depression.[20][21][22][23][24][25][26][27][28][29][30][31]

Nursing, Allied Health, and Interprofessional Team Interventions

An interprofessional team that provides an integrated approach to patient care, particularly risk factor modification, can help achieve the best overall outcomes. Risk factor modifications are stressed to patients by primary care physicians daily. A patient referral to a registered dietician is likely to be beneficial. There should also be recommendations for routine aerobic exercise. It has become widely recognized that counseling on the importance of dietary changes should include a discussion of the Mediterranean diet, although continued studies will be beneficial.[32][33] [Level 1]

Therefore, the specific requirements of a strict Mediterranean diet are not homogenous and may be difficult to recommend. There was a large scale literature review of the Mediterranean diet performed by Davis et al. that attempted to define the quantities of each food group and specific nutrients; results were as follows:

  • Three to nine servings of vegetables
  • One-half to two servings of fruit
  • One to 13 servings of cereals
  • Up to eight servings of olive oil daily
  • Red wine daily in moderation

These recommendations resulted in approximately 2200 calories (9300 kJ) per day, with 37% as total fat, 18% as monounsaturated with 9% as saturated, and 33g of fiber per day.[34] [Level 1]

Nursing, Allied Health, and Interprofessional Team Monitoring

A scoring system for adherence to the Mediterranean diet exists and would help patients to recognize the importance of adherence based on a morbidity and mortality model for the development of specific illnesses.[35] It is important to continue to routinely encourage patients to perform risk factor modifications and to provide them with the resources needed to make the necessary lifestyle changes to improve their overall health. Routine blood monitoring can be performed, including blood lipids, hemoglobin A1c, and renal function.

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Colton R. Rishor-Olney

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Melissa R. Hinson

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3/27/2023 8:40:14 PM

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