Why Was the Mediterranean Diet Made? The Story of Ancel Keys

December 24, 2025 •

3 min read

In the 1950s, American physiologist Ancel Keys observed a significantly lower incidence of heart disease in post-war populations of Southern Italy compared to affluent Americans, sparking an investigation into the role of diet in cardiovascular health. This surprising finding set the stage for what would become the renowned Mediterranean diet concept.

Quick Summary

The Mediterranean diet concept was formalized by scientist Ancel Keys after his research revealed lower heart disease rates among populations in Greece and Southern Italy. Keys' groundbreaking Seven Countries Study linked lower intake of saturated fats to better cardiovascular outcomes, contrasting sharply with the diet in the United States and Northern Europe.

Key Points

Ancel Keys' Discovery: The Mediterranean diet was conceptualized by American physiologist Ancel Keys, who observed lower heart disease rates in Southern Italy and Greece in the 1950s.
Seven Countries Study: This landmark epidemiological research, directed by Keys, provided the scientific evidence linking lower saturated fat intake and higher olive oil consumption with better cardiovascular health.
Dietary Pattern, Not Rules: The concept is not a rigid set of rules but a reflection of the traditional, plant-focused eating patterns historically practiced in Mediterranean coastal regions.
Beyond Nutrition: The 'diet' encompasses a healthy lifestyle, including regular physical activity, social connection, and shared meals, which are critical for overall well-being.
Healthy Fat Focus: A key finding was that the type of fat matters, with monounsaturated fats from olive oil being beneficial, in contrast to saturated fats prevalent in Western diets.
UNESCO Heritage: In recognition of its cultural and health significance, the Mediterranean diet was designated an Intangible Cultural Heritage of Humanity by UNESCO in 2010.

The Pioneer Behind the Research: Ancel Keys

Before the 1950s, the connection between diet and heart disease was not widely understood. American physiologist Ancel Keys changed that with his pioneering work. His interest in nutrition and health grew after observing mortality rate changes during and after famine in WWII. Keys' visit to Southern Italy in the early 1950s revealed remarkably low rates of heart disease and cholesterol among locals, despite their diet including significant fat from olive oil. This contrasted starkly with the high heart attack rates among middle-aged American men, driving Keys to find scientific proof for his hypothesis linking diet to cardiovascular health.

The Seven Countries Study: Groundbreaking Epidemiology

To test his hypothesis, Keys launched the Seven Countries Study in 1958, a major epidemiological study comparing diets and lifestyles of middle-aged men across countries like the US, Finland, Japan, Italy, and Greece. This multi-decade study tracked over 12,000 participants, documenting their diets, physical activity, and health outcomes. The study concluded that populations in Greece and Italy, with diets rich in monounsaturated fats (from olive oil) and low in saturated fats (from animal products), had significantly lower rates of coronary heart disease than those in Finland and the United States.

The "Mediterranean Paradox"

Keys' research highlighted what seemed paradoxical: high-fat intake correlating with good heart health. The crucial factor was the type of fat. Unlike the high saturated fat consumption from meat and dairy in America and Northern Europe, Mediterranean populations consumed healthy monounsaturated fats primarily from olive oil. The study solidified the understanding that the overall dietary pattern, not just total fat intake, is vital for long-term health.

Core Principles of the Mediterranean Diet

The diet Keys identified represents traditional eating patterns in the mid-20th century Mediterranean. Its key principles, emphasizing whole, plant-based foods, olive oil as the main fat source, and moderate consumption of fish and poultry while limiting red meat and sweets, are detailed on {Link: ncbi.nlm.nih.gov https://pmc.ncbi.nlm.nih.gov/articles/PMC6466433/}. This includes a comparison to the Standard American Diet of the time.

From Observation to Global Recognition

Keys and his wife shared their findings in books like How to Eat Well and Stay Well the Mediterranean Way. Later, organizations like Oldways and the Harvard School of Public Health formalized the concept with the first Mediterranean Diet Pyramid. Today, it is highly recommended and researched for preventing chronic diseases like heart disease and type 2 diabetes. UNESCO recognized its cultural significance in 2010 as Intangible Cultural Heritage of Humanity.

A Prescription for Health, Not Just a Diet

Keys' work, driven by a desire to combat heart disease, formed the basis for the modern understanding of the Mediterranean diet. It wasn't 'created' but identified and defined based on existing healthy traditions. His foundational research, seeking to understand thriving populations, shifted the focus to holistic dietary patterns rather than single nutrients. This emphasizes that lasting health comes from a balanced, culturally rich lifestyle centered on whole foods.

Conclusion

The Mediterranean diet's origin is a blend of scientific inquiry and cultural heritage. Ancel Keys' observation of better health in Southern Europe and the subsequent Seven Countries Study provided the evidence to define this heart-healthy eating pattern. This dietary model is recognized globally for its health benefits.

Frequently Asked Questions

Ancel Keys was an American physiologist and scientist who, along with his wife Margaret, first identified and defined the Mediterranean diet based on his research into diet and heart disease. He was the lead investigator for the Seven Countries Study.

The Seven Countries Study was a long-term epidemiological study led by Ancel Keys that investigated the link between diet, lifestyle, and cardiovascular disease across different nations. It provided crucial evidence supporting the health benefits of the traditional Mediterranean diet pattern.

No, the eating patterns that form the basis of the Mediterranean diet evolved over millennia as an environmentally-driven food culture. Ancel Keys and his team simply studied, defined, and popularized this existing traditional dietary pattern in the mid-20th century.

Olive oil is the principal source of added fat in the diet, providing heart-healthy monounsaturated fats. Keys noted that Mediterranean populations consumed significant fat but had low heart disease rates because it came primarily from olive oil, not saturated fats.

Yes, but in limited quantities. The traditional pattern emphasizes plant-based foods, with moderate consumption of fish and seafood. Smaller amounts of dairy (like cheese and yogurt) and poultry are included, while red meat and sweets are consumed infrequently.

Keys was surprised by the contrast in heart attack rates between American businessmen and Mediterranean populations, particularly those in southern Italy, despite Americans having higher salaries. He hypothesized that dietary differences were a key factor.

Wine is a traditional, cultural component for those who drink, typically consumed in moderation with meals. However, it is not a required element, and health benefits can be achieved without alcohol, particularly for those with contraindications.