Is the Mediterranean diet the best diet for longevity?
What we actually know about optimal nutrition and the principles you can apply.
Intro
In the health and wellness space, no topic is more divisive than nutrition. Everyone has strong opinions on what an optimal diet consists of, and everyone has evidence (albeit anecdotal) of how they resolved their health ailments through a particular style of eating. Even though people tend to get evangelical without actual data to back their claims, there is enough qualitative research to support a number of principles that, ironically, converge across different diets and approaches to nutrition.
The Mediterranean diet is one such example. Studies have shown a positive association between the Mediterranean diet and cardiovascular health, and some of its core principles can also be found in other eating styles, such as paleo, keto, and plant-based diets. In this post, I will discuss why studying nutrition is so complicated, what the most evidence-backed nutritional interventions are, and what makes the Mediterranean diet special in its correlations with increased health span and longevity.
What makes nutrition so complicated
Studying nutrition is extremely complicated for several reasons. Firstly, our complex organisms make it difficult to isolate the effects of specific nutrients or dietary patterns on health outcomes. Individual variability also plays a role, as no two people respond similarly to the same nutrients or diets, making it hard to generalize findings.
Controlling variables is also challenging, and nutrition randomized controlled trials (RCTs) are more difficult to design, implement, and interpret compared to pharmaceutical trials. Unlike simpler organisms that can be kept in controlled environments, humans have varied lifestyles, genetics, and environmental factors that influence their response to nutrition. Many health impacts of nutrition only manifest over extended periods, often decades, making them challenging to study in controlled settings. Finally, there’s the issue of compliance, which is difficult in long-term studies, as participants may not strictly adhere to specific diets or nutritional interventions.
What we know about optimal nutrition
For the reasons described above, there are many things we don’t yet understand about optimal nutrition and how it intersects with optimal health span. However, decades of research support two principles that converge across different diets:
1. Energy balance
Being either overnourished (consuming too many calories) or undernourished (not enough calories for your needs) leads to poor health outcomes.
A caloric surplus, if excessive or prolonged, can lead to a range of health problems primarily stemming from weight gain and obesity. These issues include an increased risk of cardiovascular diseases and high blood pressure, metabolic disorders like type 2 diabetes and metabolic syndrome, certain types of cancer, musculoskeletal problems, and hormonal imbalances, potentially affecting fertility and bone health.
Conversely, drastic caloric restriction can lead to undernourishment and cause severe physical and cognitive impairments, weakening the body's immune system and making it more susceptible to infections and diseases. It can lead to muscle wasting, decreased bone density, and organ dysfunction. Cognitive functions may be impaired, affecting memory, concentration, and learning abilities. Undernourishment can also result in anemia, fatigue, weakness, and hormonal imbalances.
A side note on caloric restriction: when controlled for adequate nourishment (without malnutrition), it has been shown to increase maximal lifespan and healthspan in rodents, and may have similar effects in humans, but further studies are necessary in order to identify the molecular and cellular mechanisms for its therapeutic effect.
Energy consumption relative to energy expenditure determines energy balance, and energy balance really matters; there is no way around it. Anyone who tries to convince you that there is a different mechanism for weight management (both weight loss and weight gain) is not using science to support their claims. However, the types of calories you consume also matter, which leads us to the next point.
2. Nutrient density
Consuming enough macro and micronutrients can only be achieved through eating a whole food diet with very minimal processed foods. Whole, minimally processed food includes vegetables, fruit, proteins, healthy fats and some whole grains. These foods provide a high amount of nutrients relative to their calorie content.
Protein, healthy fats, unrefined carbohydrates and fiber support virtually all bodily functions and structures. More variety across these macros also helps ensure you are getting more micronutrients (vitamins and minerals) as well as maintaining a rich and healthy microbiome. On the other hand, a poor diet (low in protein, low in nutrients) is also more correlated with overeating highly palatable foods (processed foods) and nutrient deficiencies.
The Mediterranean diet and longevity
The Mediterranean diet is an eating pattern inspired by the traditional dietary habits of people living in countries bordering the Mediterranean Sea, particularly southern Italy, Greece, and Spain in the mid-20th century. There is no single "Mediterranean diet" as dietary habits vary among different Mediterranean countries and regions, but some general principles apply across the board:
Abundance of fiber: the diet is rich in vegetables, fruits, whole grains, legumes, nuts, and seeds.
Healthy fats: olive oil is the primary source of fat, with moderate consumption of fish providing omega-3 fatty acids.
Moderate protein: moderate amounts of fish, poultry, eggs, and dairy (mostly cheese and yogurt) are the primary source of protein.
Limited red meat: consumption of red meat is low.
Minimally processed foods: the diet consists of whole, minimally processed foods with very few refined and ultra-processed options.
While there have not been any clinically significant studies to assess the direct correlation between the Mediterranean diet and longevity, there is strong evidence that the Mediterranean diet promotes cardiovascular health and may reduce risks of certain diseases associated with mortality.
RCTs that examine long-term health outcomes rather than just short-term effects tend to be more robust. One such study is the The PREDIMED (Prevención con Dieta Mediterránea), a landmark randomized controlled trial that investigated the effects of the Mediterranean diet on cardiovascular disease prevention.
The study was conducted in Spain from 2003 to 2011. It involved 7,447 participants aged 55-80 who were at high risk for cardiovascular disease but did not have it at enrollment. Participants were randomly assigned to one of three dietary interventions: a Mediterranean diet supplemented with extra-virgin olive oil, a Mediterranean diet supplemented with mixed nuts, or a control diet (advice to follow a low-fat diet). The primary outcome was a composite of myocardial infarction, stroke, and cardiovascular death.
After an average follow-up of 4.8 years, both Mediterranean diet groups showed approximately a 30% reduction in the risk of major cardiovascular events compared to the control group. While the study faced some issues with randomization procedures that led to a retraction and republication in 2018, the reanalysis confirmed the original findings.
What we know beyond a doubt is that longevity is significantly impacted by chronic diseases. Chronic diseases like heart disease, stroke, diabetes, chronic lung disease, and Alzheimer's disease are among the top causes of death and have remained so for decades. Nearly all chronic diseases are impacted by metabolic health, and nutrition plays a very important part in it. So, if the Mediterranean diet can improve metabolic health, this could, indirectly, also have a positive impact on longevity.
The one caveat I would add is that muscle mass and bone mineral density are also important aspects of longevity. The "classic" Mediterranean diet might be too low in protein for most people, especially elderly individuals who are at an increased risk of muscle loss. Here’s where the gene-environment interaction really matters, as it would be unfair to compare someone living in southern Greece and eating a Mediterranean diet with someone living in South Dakota and eating the same diet. Not only does the person in southern Greece have a different genetic make-up, but they are also exposed to an entirely different environment (pollution, food quality, sunshine, etc.) that will impact their dietary needs and longevity.
TL;DR
The Mediterranean diet hits the mark on almost all counts for what an optimal diet would look like based on the evidence we have. To further adapt it to a modern, more sedentary lifestyle with less access to year-round sunshine and locally-sourced foods, I would slightly increase protein intake while reducing grain intake. Many grains consumed in the US are refined, which means the bran and germ have been removed, leaving only the endosperm. This process strips away many nutrients and fiber.
The “best” diet will always be the one you can adhere to and nobody can provide a blueprint, this is something you need to determine empirically. But if you want to use data to inform your nutrition, just follow these guidelines and worry less about the name of the diet:
eat enough protein
eat enough fiber
don’t eat processed foods
don’t eat too many or too few calories for your individual needs
Final note on the problem with the Blue Zones
People often assume that The Mediterranean diet and the Blue Zones diet are the same. While they share some similarities, they are not identical. The Blue Zones diet is based on the eating habits of specific longevity hotspots around the world, including regions outside the Mediterranean, such as Okinawa, Japan, and Nicoya, Costa Rica. In fact, of the five Blue Zones, only two are in the Mediterranean: Icaria, Greece and Ogliastra, Sardinia, Italy.
Blue Zones are specific geographic areas where people are claimed to live significantly longer than average. The concept was popularized by Dan Buettner (author, not scientist) who identified five such regions:
Icaria, Greece
Ogliastra, Sardinia, Italy
Okinawa, Japan
Nicoya Peninsula, Costa Rica
Loma Linda, California, USA
People in these areas were reported to have lower rates of chronic diseases and longer life expectancies. Buettner and his team attributed this longevity to common lifestyle factors they observed, including natural movement, having a sense of purpose, stress reduction, moderate alcohol consumption, and a plant-based diet.
However, the validity of Blue Zones as areas of exceptional longevity has been challenged by further research and analysis:
Statistical issues: some researchers argue that the apparent longevity in these regions may be due to statistical errors or data quality problems rather than actual longer lifespans.
Limited timeframe: a study on the Nicoya region in Costa Rica found that the longevity effect was limited to men born between 1905 and 1930, suggesting it may not be a consistent or ongoing phenomenon.
Data discrepancies: in Okinawa, for example, a significant percentage of reported centenarians were revealed to be deceased or missing when records were updated.
Contradictory evidence: some Blue Zones, like Loma Linda, California, actually have lower life expectancies than many other places.
Potential for bias: critics argue that the Blue Zones concept may cherry-pick data to support a pre-existing narrative.
At best, the Blue Zones are based on epidemiology and observational research rather than controlled scientific studies. While the lifestyle factors promoted by the Blue Zones concept (such as regular physical activity, stress reduction, and a plant-based diet) are generally associated with good health, the idea that these specific geographic areas have exceptionally long-lived populations is questionable.