What is the Mediterranean diet?

The Mediterranean Diet: A Comprehensive Overview

The Mediterranean diet is a heart-healthy eating pattern characterized by high consumption of olive oil, vegetables, fruits, whole grains, legumes, nuts, and fish, with moderate wine intake and limited red meat, which reduces cardiovascular disease risk by 30% and lowers coronary heart disease risk by 29-69%. 1, 2

Core Food Components

The Mediterranean diet consists of specific food groups consumed in defined proportions:

Primary Foods (Daily Consumption)

• Olive oil serves as the primary fat source, with extra virgin olive oil recommended at approximately 1 liter per week or as the main cooking and dressing oil 1
• Abundant plant foods including vegetables, fruits, whole grains, and legumes consumed daily 1, 2
• Nuts intake of 30 grams daily of mixed nuts (walnuts, hazelnuts, almonds) 1
• Dietary fiber intake of 27-37 grams per day, which is double the current US average intake 1, 2

Regular Foods (Weekly Consumption)

• Fish and seafood at least twice weekly as a primary protein source 2
• Moderate portions of poultry, eggs, and yogurt throughout the week 2
• Low to moderate dairy products, primarily in the form of cheese and yogurt 1

Limited Foods (Occasional Consumption)

• Red meat consumed only a few times per month in small portions 1, 2
• Sweets and sugar-sweetened beverages consumed sparingly 2
• Moderate wine consumption, typically with meals 1, 2

Macronutrient Composition

The diet provides specific macronutrient ratios that distinguish it from other healthy eating patterns:

• Total fat accounts for 32-43% of total energy, which is higher than traditional low-fat diets 1, 2
• Saturated fat comprises only 8% of calories 1
• Monounsaturated fat (MUFA) provides 12-22% of calories, primarily from olive oil 1
• Polyunsaturated fat (PUFA) accounts for 7-8% of calories, with emphasis on omega-3 fatty acids from fish and plant sources 1, 2

Key Nutritional Characteristics

The Mediterranean diet is distinguished by several unique nutritional features:

• Rich in polyphenols from olive oil, fruits, vegetables, and wine, which provide antioxidant and anti-inflammatory effects 1, 3
• High in monounsaturated and polyunsaturated fatty acids while maintaining low saturated fat intake 1, 4
• Well-balanced omega-6 to omega-3 fatty acid ratio from fish, nuts, and plant sources 4, 5
• Abundant phytonutrients, vitamins, and antioxidants from diverse plant foods 3, 5

Cardiovascular and Metabolic Benefits

The Mediterranean diet demonstrates robust evidence for cardiovascular protection:

Cardiovascular Disease Reduction

• The landmark PREDIMED trial demonstrated a 30% reduced risk for myocardial infarction, stroke, and cardiovascular mortality after 4.8 years when comparing Mediterranean diet supplemented with olive oil or nuts versus a control low-fat diet 1
• Coronary heart disease risk reduced by 29-69% and stroke risk reduced by 13-53% with adherence to this dietary pattern 1, 2
• Every 2-point increase in adherence to the Mediterranean diet results in a 10% reduction in cardiovascular disease events 1, 2
• The Lyon Diet Heart Study showed a 72% reduction in recurrent myocardial infarction risk after 4 years in secondary prevention, despite no differences in cholesterol levels between groups 1

Blood Pressure Effects

• Lowers systolic blood pressure by 6-7 mm Hg and diastolic blood pressure by 2-3 mm Hg 1, 2

Lipid Profile Improvements

• Reduces triglycerides by 10-15% compared to low-fat diets 1
• The PREDIMED study showed reduced hypertriglyceridemia prevalence from 21.3% in controls to 12.3-13.6% in Mediterranean diet groups after one year 1
• Improves LDL-C, non-HDL-C, and LDL particle quality 1

Mortality Benefits

• Lower all-cause mortality rates among those adhering to the Mediterranean diet 1
• Adult life expectancy was among the highest in the world in regions following this dietary pattern in the early 1960s 6

Additional Health Benefits

• Type 2 diabetes risk decreases by 14% with adherence to this dietary pattern 1
• Lower rates of heart failure development 1
• Reduces inflammation through multiple dietary components 1
• Promotes beneficial gut microbiota through high fiber content and polyphenols 1

Mechanisms of Action

The Mediterranean diet exerts its protective effects through multiple biological mechanisms:

• Lipid-lowering effects from high intake of monounsaturated and polyunsaturated fatty acids 3
• Anti-oxidative effects from abundant polyphenols, vitamins, and phytonutrients 3, 5
• Anti-inflammatory properties from omega-3 fatty acids and polyphenols 1, 4
• Antimicrobial effects from various bioactive compounds 3
• Anticancer properties demonstrated in multiple studies 3

Comparison with Other Healthy Dietary Patterns

The Mediterranean diet shares similarities with other evidence-based dietary patterns but has unique distinguishing features:

Similarities with DASH Diet

• Both emphasize fruits, vegetables, whole grains, and limited red meat 1, 2
• The American Heart Association notes that the Mediterranean diet, DASH diet, and AHA dietary pattern are "more similar than dissimilar" in their cardiovascular benefits 1, 2

Key Differences from DASH Diet

• The Mediterranean diet is lower in dairy products compared to the DASH diet 1, 2
• Higher intake of olive oil and seafood distinguishes the Mediterranean pattern 1, 2
• Includes moderate wine consumption, while DASH does not emphasize this component 1, 2
• DASH focuses more on low-fat dairy and sodium restriction (1500-2300 mg/day), while the Mediterranean diet emphasizes fat quality over quantity 1

Clinical Applications and Special Populations

The Mediterranean diet shows particular benefit in specific clinical scenarios:

• High cardiovascular risk patients with multiple risk factors benefit most from this dietary pattern 1
• Metabolic syndrome with elevated triglycerides responds well to the triglyceride-lowering effects 1
• Type 2 diabetes with dyslipidemia shows improved glycemic control and lipid profiles 1
• Pediatric primary dyslipidemia can be managed with this diet as first-line therapy 1

Important Clinical Considerations and Implementation

Ad Libitum Consumption

• The Mediterranean diet can be consumed without strict portion control or caloric restriction, as demonstrated by the PREDIMED trial showing cardiovascular benefits without weight loss requirements 1
• The 2015 Dietary Guidelines Advisory Committee identified the Mediterranean-style pattern as one of three healthy dietary patterns that can be consumed without strict portion control 1

Pattern Over Individual Components

• Focus on the complete dietary pattern rather than individual nutrients or foods, as the American College of Cardiology recommends, since secondary analyses from PREDIMED showed that synergistic effects of the complete dietary pattern were most important 1
• The quality of fat matters more than quantity, explaining why this diet is superior to traditional low-fat diets for lipid management despite higher total fat content 1

Adherence and Measurement

• Adherence to the Mediterranean diet can be measured using scoring systems that assess intake of key components 1
• Effectiveness depends on adherence to the overall pattern rather than individual components 1

Sustainability and Cultural Adaptability

• The Mediterranean diet is considered environmentally sustainable 3
• This dietary pattern is not exclusively confined to the Mediterranean Basin, as regions with Mediterranean climates (such as Central Chile) have similar agriculture and culinary traditions that can support this eating pattern 5
• Regular physical activity was historically associated with this dietary pattern and contributed to low rates of obesity 6

Common Pitfalls to Avoid

• Do not focus on individual "superfoods" but rather emphasize the complete dietary pattern for maximum benefit 1
• Avoid misinterpreting the wine component as a requirement; the inclusion of alcoholic beverages in a healthy diet is becoming increasingly controversial, and ongoing trials are investigating this question 7
• Do not restrict total fat intake in an attempt to make the diet "healthier," as the higher fat content (32-43% of total energy) is a defining characteristic that contributes to cardiovascular benefits 1
• Ensure adequate fiber intake of 27-37 grams daily, as this is double the current US average and critical for the diet's benefits 1, 2