Arguably the most studied diet of the past seventy years, the so-called ‘Mediterranean diet’ is based on the eating habits of populations living in countries bordering the Mediterranean Sea, particularly Southern Italy, Spain, and Greece. Compared with people residing in Northern Europe or North America, the population of this region tends to have greater longevity and a lower occurrence of chronic degenerative diseases. Discussing the role played by a Mediterranean-style diet in conferring these advantages, a recent paper by researchers from Italy analyzes how its nutrient content can help prevent the onset of today’s most common diseases.
Published in the AIMS Public Health journal, the paper describes how the key components on which the Mediterranean diet has historically been based include fruit and vegetables in large quantities, whole grains, legumes and nuts, olive oil, yogurt, moderate amounts of cheese, a maximum of around four eggs per week, with small amounts of meat, fish, and wine. Noting how the benefit of such a dietary regimen lies in its ability to maintain health and improve longevity, the researchers summarize key studies linking it to the prevention and treatment of diabetes, cardiovascular diseases, cancer, Alzheimer’s disease, and cognitive decline.
Describing how the Mediterranean diet is greatly beneficial in the prevention of type 2 diabetes and allows diabetics to achieve better control over their blood glucose, the paper notes that the American Diabetes Association and American Heart Association recommend this dietary regimen as a means of improving glycemic control and cardiovascular risk factors. The researchers suggest that the mechanisms behind these diabetic benefits are related to an antioxidant and anti-inflammatory action peculiar to the various phytonutrients which the cornerstone foods of the Mediterranean diet are rich in.
The paper states that the generation of harmful oxidative stress is one of the causes of chronic degenerative diseases. To help guard against oxidative damage, the researchers explain, the body’s main cellular defense mechanisms include enzymes such as catalase, superoxide dismutase, and glutathione peroxidase. The cellular production of these vital enzymes requires intake of the minerals iron, copper, selenium, and zinc.
Noting that additional help in carrying out antioxidant action is supplied by vitamins A, C and E, as well as phytonutrients such as flavonoids, lutein, and lycopene, the researchers describe how these nutrients are found in foods such as watermelon, apples, grapes, red fruits, tomatoes, and green leafy vegetables. Such foods are also valuable sources of minerals. The researchers stress that dietary intake of these nutrients is extremely important for preventing and treating cardiovascular disorders.
The researchers further note that the consumption of fish results in an increased intake of omega-3 fatty acids, adding that the role of these particular substances in helping to prevent cardiovascular disease is now universally recognized.
Reporting that numerous studies have highlighted a correlation between the Mediterranean diet and the prevention of several forms of cancer, the researchers say the introduction of polyphenols into the diet seems able to reduce breast cancer and its recurrence.
Looking at colorectal cancer, the paper cites a study carried out in Spain that included around 41,000 people aged between 29 and 69 years old. Evaluating the preventive effects of diet against the onset of this disease, the study was based on a comparison of three different dietary patterns: a ‘Western’ diet, with high intakes of saturated fats from dairy products and red meat, refined grains, caloric drinks, and sweets; a ‘Prudent’ diet, with use of light cheeses, vegetables, fruits, whole grains, and juices; and the Mediterranean diet, with consumption of fish, legumes, vegetables, whole grains, boiled potatoes, fruit, olive oil, and low consumption of juices.
The study found that the Mediterranean diet had a protective action against colorectal cancer, while the Western diet carried an increased risk of the disease developing. Interestingly, the Prudent diet did not seem to influence the frequency of occurrence of this form of cancer. The researchers suggest that the protective action of the Mediterranean diet may be related to factors including the increased introduction of antioxidant nutrients and the creation of a favorable microbiota.
The researchers say that predisposing factors for Alzheimer’s disease include deficiencies of antioxidant nutrients such as vitamins C, E, B6, B12, and folate. Suggesting that the introduction of these nutrients could play a preventative role, they cite a study carried out on 1,864 elderly people living in Greece which found that adherence to the Mediterranean diet may have a beneficial effect against cognitive impairment. Similarly, a UK study of more than 500,000 participants reported that the higher the adherence to a Mediterranean diet, the lower the risk of dementia independent of genetic factors.
In the conclusion to their paper the researchers point out that, in recent decades, the principles on which the Mediterranean diet is based have been lost even in the Mediterranean countries themselves. In their place there has been an increasing move towards the consumption of ultra-processed, high-calorie, and low-fiber foods.
Towards remedying this, the researchers argue that choices made by the governments both of high-income and developing countries alike should encourage the production and consumption of those foods that characterized the original Mediterranean diet. This, they say, would be reflected in a decrease in healthcare spending. With ultra-processed products becoming increasingly dominant in the global food system, the time for change is now.