Affecting more than 300 million people around the globe, depression is one of the most prevalent, costly, and debilitating forms of mental illness. Further, rates of depression have been on the rise since the COVID-19 pandemic. Depression and mood disorders are more common among women and negatively impact the quality of life, particularly as we age. While many factors are associated with an individual’s mental health, diet and food consumption have become hotly researched topics for their proposed association with mood. 

Early studies have found an association between Mediterranean and plant-based diets and a lower likelihood of depression; however, this has been quite challenging to study due to the ‘chicken and the egg’ phenomenon. Could it be that a healthy diet can lead to an improved mood? Or could individuals be consuming an unhealthy diet due to pre-existing depression, resulting in a loss of interest in daily activities like cooking and grocery shopping? 

A 2023 paper published by Chiara Marche of Italy’s University of Sassari set out to answer this question by studying the association between dietary patterns and mood amongst individuals living in Sardinia, Italy – an area well known for its population’s longevity. The mountainous island region of Sardinia is one of the few areas considered to be a ‘Blue Zone’ – an area of the globe occupied by exceptionally long-lived people. The Blue Zones also include the Okinawa Islands in Japan, Ikaria in Greece, and Costa Rica’s Nicoya peninsula. Not only is the physical health of individuals residing in Blue Zones preserved into old age, but older people also report fewer depression symptoms and greater life satisfaction and optimism than those individuals living in more metropolitan areas. Over the past century, research efforts have attempted to shed light on the features associated with their longevity in hopes that they can be expanded to the global population. 

Published in the journal Nutritional Neuroscience, Marche’s team recruited 200 older adults (with an average age of 93.9 years old!) from central Sardinia to complete screening questionnaires measuring symptoms of depression and anxiety as well as rate the frequency of consumption of various types of foods. Interestingly, the authors found that consuming moderate animal-derived foods and fats was associated with better overall mood. On further analysis, they found that olive oil consistently positively correlated with mood, even after accounting for other factors influencing mood, such as income and occupation. These findings reinforce that a balanced diet, including plant- and animal-derived fats and proteins, may benefit mood – particularly among the elderly. 

But how does this finding stack up with the diets of individuals from the other various Blue Zones? Giovanni Pes and his team from the Sardinia Longevity Blue Zone Observatory published an article in 2022 in the journal Maturitas comparing diets across the four regions. The specific eating habits are quite different from one another and are highly influenced by the different cultural traditions, environment, and occupational demands of each population. However, similarly to the finding described above, a common feature amongst all Blue Zones was the moderate intake of animal-based proteins. 

Notably, most livestock consumed were allowed to graze over large territories with enriched and biodiverse soils – both likely make their meat more nutritious and leaner than those cultivated from large-scale commercial farms and found in our large retailers. In addition, the livelihood of individuals in these regions was predominantly agricultural or animal husbandry – both highly physically demanding and necessitated adequate protein consumption. 

The Blue Zones provide an exciting population to study for their longevity, overall health and unique dietary habits. Despite some limitations of both studies, the key message seems to be the same – a balanced, nutrient-dense diet can support health and overall wellness as we age.