The proportion of older people in the world’s population is growing. Their increase is due to the aging of the baby boom generation, declining birth rates, and the significant decline in age-related mortality since 1950 ^[1][2][3][1,2,3], so that there are now 727 million older people (aged 65 and over) and half a million centenarians (aged 100 and over) in the world [4]. By 2050, the 65+ population is expected to double to over 1.6 billion [4].

Under this scenario, maintaining vigor, resilience, and acceptable levels of health and functional autonomy across the lifespan is a major challenge and a research priority for individual well-being and for ensuring the economic sustainability of healthcare systems. Longevity is rightly regarded as one of the greatest achievements of modern society, not only as a function of lifespan, but, more importantly, as a function of healthspan [5]. Longevity is measured by age, and a person who is at least eighty-five years old is usually considered to have a long life. Each year lived at a very old age is significantly more extraordinary than the previous one, because the extreme limits of the human lifespan have been reached. Centenarians are individuals who have reached an exceptionally advanced age ^[2][6][2,6]. Centenarian status is sufficiently rare yet convenient for case–control studies because it is an easily understood and well accepted criterion of longevity. According to a number of studies, these individuals have a lower incidence of chronic diseases ^[7][8][7,8], a lower incidence of morbidity ^[9][10][9,10], and a longer healthy lifespan ^[11][12][11,12]. Thus, several studies in countries around the world, including Italy ^[5][13][14][5,13,14], Germany [15], Japan, and the United States [16], made the list of centenarians. Because the number of people who survive to old age is small, many prospective cohort studies have focused on reaching less extreme ages, such as 85, 90, or 95 [11]. Scientific studies in long-lived populations are important because they allow us to understand what factors can modify the epigenome over a lifetime and have beneficial effects on health ^[17][18][19][17,18,19]. Over the past two decades, research has sought to elucidate the factors that contribute to longevity and whether there are lessons that can be applied to the general population. Many studies have linked genetic ^[20][21][22][20,21,22], macroenvironmental ^[5][14][23][5,14,23], and microenvironmental ^[24][25][26][24,25,26] factors to longevity in humans.

The discovery of Longevity Blue Zones (LBZs), geographic areas characterized by a significant proportion of residents who live exceptionally long lives and often escape age-related disability, has captured the interest of scientists. These areas include residents of Okinawa, Japan; the Nicoya Peninsula, Costa Rica; Loma Linda, California; Icaria, Greece; and centenarians in the province of Ogliastra, Sardinia. These populations hold great promise for identifying key factors in the maintenance of function during aging ^[27][28][27,28], and several studies have highlighted isolation, lifestyle, and diet as hallmarks of longevity ^{[29][30][31][32][33]}[29,30,31,32,33]. It is important to note that, while there are similarities between long-lived populations, there is no single formula for longevity. In addition to Sardinia, several other Italian regions have high numbers of nonagenarians and centenarians ^[34][35][34,35], such as Cilento, where several recent studies have focused on longevity ^{[5][14][26][36][37]}[5,14,26,36,37]. Cilento, with a considerable number of old people and a number of factors that increase longevity, can be considered an undisclosed Blue Zone and can be compared with other Blue Zones in order to highlight factors that may be associated with increased longevity.

Cilento is located in the Campania region of southern Italy, and part of its territory is listed as a UNESCO World Heritage Site. It covers an area of about 490,000 hectares and includes 102 municipalities. From an ecological point of view, it is a heterogeneous territory, characterized by the integration of different environments, including coastal, hilly, and mountainous areas [5], as well as the mouths of major rivers, the latter thanks to karst phenomena with favorable lithological features ^[38][39][40,41]. Springs are scattered in hilly and coastal areas ^[26][35][40][26,35,42]. In this area, humans have been able to integrate themselves harmoniously with the forms of the landscape ^[41][43] in a rural, agricultural, and pastoral civilization [5]. The population of Cilento is about 278,093, and the percentage of old people (40.31 per 1000) is relatively high ^[42][44]. The prevalence ratio of centenarians is 12.49 [14]. The long life expectancy in Cilento has been found to be most pronounced in the central municipalities of the area, from where it spreads to the southeastern part of the territory, according to age groups [5]. Aliberti et al. [5] reported that centenarians are found in the heart of the defined area, at an altitude between 440 and 600 m above sea level (hilly area). The region has a transitional climate between the Mediterranean and the temperate zone, with mild temperatures of about 20 degrees Celsius, rather humid winters, and moderately dry summers [5]. The mild climate seems to be an important factor in the phenomenon of longevity in Cilento.

Surrounded by an ideal geomorphology and a healthy and mild climate ^[41][43], the rural area of Cilento has allowed the cultivation of Aloe Vera. According to several studies ^[43][44][45][54,55,56], Aloe Vera gel is used as a food with beneficial properties, such as anti-inflammatory, antioxidant, antiviral, and antibacterial properties, with other antihypertensive, antidiabetic, anti-obesity, and cardioprotective effects. Therefore, the rural area of Cilento, where longevity is located, is “different from the other regions of Italy, both for cultural traditions and for the availability of typical products” ^[46][57] (p. 2), which allow the creation of a unique traditional cuisine. For example, Caggiano presents as a typical dish “tagliatelle con i fiori di zucca” (tagliatelle with pumpkin flowers); Sicignano degli Alburni presents “lagane con la mollica” (lagane with breadcrumbs); Controne offers “minestra di fagioli e cardoncelli” (bean and cardoncelli soup) and “carciofi farciti” (stuffed artichokes); and typical of Buccino is “gallo imbottito” (stuffed cockerel) ^[41][43]. A number of studies in the Cilento region have found that longevity is associated with the adoption of behaviors that are typical of rural areas. For example, Scelzo and colleagues [36] found that those living in the rural hills of the area adopted a way of life that included hard work, love of the land, family, and religion, which allowed them to maintain mental well-being and made them particularly resilient and optimistic. The study by Pizza et al. [26] on the nonagenarians of Cilento also emphasized the importance of lifestyle and diet, but also the importance of individual personality factors.

2.2. Okinawa

Okinawa Island is the southernmost prefecture of Japan and is part of the Ryukyu Archipelago. It covers an area of about 226,500 hectares. The northern part of the island is covered with forests, has a mountainous terrain, and is rich in igneous rocks. The south-eastern part of the island has only gentle limestone slopes ^[47][61]. This is where most of the population centers are located. The climate of the island is subtropical. It is hot and humid, with relatively strong seasonal tropical storms ^[47][61]. The island has two growing seasons, making it ideal for the production of fresh vegetables. Okinawans are known for their long life expectancy, high number of centenarians, and consequently low risk of age-related diseases in a population of approximately 1,285,000 ^[48][39]. Much of Okinawa’s longevity advantage is attributed to a healthy lifestyle, including the traditional diet ^[49][50][62,63], which is low in calories but rich in nutrients, especially vitamins, minerals, and phytonutrients in the form of antioxidants and flavonoids, many of which have nutraceutical potential. Compared to the Japanese diet, the traditional Okinawan diet shares similarities, including high vegetable and soy intake, low fat intake, preference for miso, an abundance of fish and seafood, and the absence of dairy products, but differs drastically in some key areas ^[49][50][62,63]. Okinawan-style miso soup is the start of a typical meal. Unlike the Japanese version, Okinawans prefer to garnish their miso soup with small amounts of tofu, fish, pork, or vegetables. “Champuru”, “nbushi”, and “irichi” are the three main styles of cooking. The main course is usually a “champuru” (stir-fried) vegetable dish. Vegetables such as bitter gourd, cabbage, bamboo shoots, etc., are accompanied by a garnish such as “konbu seaweed” (konbu seaweed is high in iodine, which is necessary for growth, and is an excellent source of glutamate). They are usually cooked with a little oil or pork fat, bonito broth (for flavor), and a little cooked fish or pork. In the “nbushi” style, watery vegetables, such as daikon (a type of large white radish), Chinese okra, carrots, or pumpkin, are flavored with miso and cooked in their own juices. The “Irichi” style uses a combination of boiling and frying and focuses on vegetables that are less watery. Favorite vegetables include burdock, seaweed, dried daikon, and green papaya. Freshly brewed “sanpin” (jasmine) tea is typically served, sometimes followed by locally produced awamori (millet brandy) ^[49][51][62,64]. The extraordinary longevity of the Okinawans has also been associated with a calorie-restricted diet ^[52][53][66,67]. Because the life-extending effects of caloric restriction have been observed in yeast and animals across the evolutionary spectrum ^[54][55][56][68,69,70], it is hypothesized that they are applicable to humans ^[48][39]. Suzuki ^[57][71] reported an average daily energy intake of 1407 kcal/day for men and 1096 kcal/day for women, while a study by Willcox et al. ^[50][63] reported an average daily energy intake of less than 2000 kcal/day for a 70-year-old man. As a way of life, before eating, people say “Hara Hachi Bu”, which means “8 out of 10”, or stop eating when the stomach feels 80 percent full. This has led to a lower incidence of obesity in Okinawa ^[58][65]. In rural areas, people live with low furniture, so they have to get up and down all the time, so they exercise by strengthening the trunk and lower body and improving balance (like doing squats). Everyone has a garden. This is a great place for daily light exercise ^[58][65]. There are groups of people called “moai” who are socially active and engage in fundraising and help each other in times of need. It is all friends getting together and talking. In America, loneliness can take 15 years off your life expectancy. In Okinawa, those years are gained simply by making friends, caring for them, and spending time with them every day. Ikigai is a mission, a purpose. It is the foundation of the well-being of the life in Okinawa. In Japan, people do not talk about retirement. They always keep their minds busy and their bodies moving. This is the meaning of their lives; it constitutes their essence. 

2.3. Sardinia

Sardinia is an island in the south of Italy, surrounded by the Mediterranean Sea. An ecologically heterogeneous area characterized by the integration of different environments, including coastal, hilly, and mountainous areas, and by the presence of lakes, with a total surface area of 2,410,000 hectares. The area of greatest longevity, identified in the hilly part of Sardinia, comprises the group of six municipalities in the provinces of Barbagia and Ogliastra, with a total surface area of 315,500 ha, and the municipality of Villagrande-Strisaili, which represents the center of the LBZ ^[59][85]. Sardinia has a population of about 1578,146 ^[60][74] people, and the prevalence ratio of old people is 5.91. The prevalence ratio of centenarians is 0.37. They are mainly engaged in pastoral and agricultural activities and live a relatively traditional lifestyle. These populations have been isolated for centuries, which has contributed to making their genetic heritage more homogeneous and preserving their sociocultural and anthropological characteristics throughout their history ^[61][86]. Non-genetic factors, such as physical activity ^[62][63][87,88], life satisfaction, optimism, resilience, religiosity ^[63][88], and diet, may explain the exceptional life expectancy recorded in central Sardinia ^[27][64][27,76]. The modern Sardinian diet has its historical origins in a mixture of agricultural and pastoral traditions ^[65][89] and can be considered a variant of the Mediterranean diet, with a slightly higher consumption of animal products, such as cheese, meat, and lard. The main staple of the diet is whole-grain bread ^[27][65][27,89]. The process of making bread (simple carbohydrates) is very different from ordinary white bread because it is leavened with a bacterium called Lactobacillus, which is capable of reducing the glycemic load of an entire meal. Maioli et al. ^[66][90] showed that sourdough bread was able to reduce postprandial glucose levels by 25%. In addition, many complex carbohydrates, such as whole grains, vegetables, and beans, are consumed. The traditional minestrone, made with onions, fennel, carrots, legumes (beans, broad beans, and peas), and lots of potatoes, is also very popular. To the traditional soup, however, are added pieces of fried bacon. In Sardinia, carbohydrate consumption has been associated with improved life satisfaction ^[67][91] and reduced diabetes. 

2.4. Ikaria

Located in the Eastern Aegean, between Samos and Mykonos, the island of Ikaria is part of the Eastern Sporades. It covers an area of 25,532 hectares and is divided into three municipalities: the municipality of Saint Kirykos, which is the capital and the southern port of the island; the municipality of Evdilos, which is the northern port; and the municipality of Rahes, which is located in the central–western part of the island. Ikaria is entirely composed of crystalline schist of metamorphic origin. The topography varies from green slopes to barren and rugged cliffs. Most of the island is mountainous. Due to the geological and tectonic structure, the island has rich aquifers and many springs ^[68][69][99,100]. Most of the villages are located in the lowlands close to the coast at an altitude of about 457 m above sea level, while some are located in the mountains ^[70][71][101,102]. The island’s climate is typically Mediterranean. The average annual temperature is 19.3 °C ^[72][78]. Most of Ikaria is included in the NATURA 2000 network for nature conservation due to its biophysical diversity ^[73][98]. With a population of approximately 8300, Ikaria has a life expectancy comparable to other long-lived populations [28]. Historical documents, such as the 17th century reports of Archbishop Joseph Georgirenes, noted the exceptional health and longevity of the islanders, attributing it to the quality of the air and water ^[74][103]. The Ikarians had to learn how to survive in a barren, rocky place, and this stimulated a resilience not seen in other places. They had to develop the ability to live off the land; to recognize plants as food sources, as vegetables, as herbs, and even as medicines; to harness bees; and, above all, to cooperate in the hardest of times. The population, though small, has maintained relatively good health despite factors such as low socioeconomic status and the presence of cardiovascular risk factors ^[68][99]. Agriculture is the most common occupation in Ikaria, which is not surprising given the island’s location, and goat meat, milk, and cheese are staples ^[69][100]. The diet is typically Mediterranean, rich in olive oil, vegetables, fruits, legumes, and local products. Locally produced olive oil, with its higher concentration of polyphenols, has been associated with vascular protection ^[75][104].

2.5. Nicoya

Located in the northeastern part of Costa Rica, on the Pacific Ocean, is the Nicoya Peninsula. Nicoya covers an area of 31,060 hectares in the province of Guanacaste. The landscape of the region is characterized by tropical dry forests and pastures and a tropical climate with a dry season from December to April and a rainy season from May to November ^[76][106]. The peninsula includes the following five neighboring cantons: Santa Cruz, Carrillo, Nicoya, Nandayure, and Hojancha, with altitudes ranging from 100 to 500 m. Nicoya has an altitude of 400 m above sea level. The total population of the five cantons is 161,000, of which 47% live in urban areas, mostly in three small towns of about 25,000 people—Nicoya, Santa Cruz, and Philadelphia—according to the 2011 census. Eight percent of the population is 65 years of age or older. According to the 2011 census, Nicoya had 32 centenarians, and the overall mortality rate was 20% lower than in the rest of the country ^[77][78][77,107]. The longevity advantage is more pronounced among men and is attributed to a lower incidence of cardiovascular disease ^[79][108]. Rosquillas are a typical dish in Nicoya. One of the reasons for the long life in Nicoya is the diet of beans, squash, and corn, called “the three sisters”. It is the triad of the Mesoamerican diet that has been consumed by the inhabitants of this region for at least 6000 years. Corn, often in the form of tortillas, is one of the staples of traditional cuisine. The kernels are an excellent source of complex carbohydrates, rich in vitamins, minerals, and fiber. And the classic preparation of corn increases its nutritional value, starting with the ash that women add when they soak the corn. The ash breaks down the cell walls of the kernels, releasing niacin, which helps control cholesterol. Black beans contain the same antioxidants as blueberries and are rich in fiber, which helps cleanse the colon. Pumpkin is a good source of vitamins A, B, and C and is rich in minerals such as potassium and magnesium ^[80][81]. Agriculture and pastoralism are the most common occupations in Nicoya, with a predominantly plant-based diet and low consumption of red meat ^[80][81]. The indigenous population of the region, especially the Chorotega ethnic group, which makes up 5 percent of the population, influences the local lifestyle and behavior ^[81][113]. The lifestyle is characterized by traditional occupations; Nicoyans do everything by hand; there are no machines for housework or gardening. They use machetes to cut grass and split wood, grind corn by hand, and carry out household activities, gathering and preparing food, and this involves unconscious movements that end up being more physical activity than exercise. They are very active in the morning and rest in the afternoon ^[80][81].

2.6. Loma Linda

Loma Linda is not an exotic place, but a small town in the middle of an American province, located about a hundred kilometers from Los Angeles, between the peaks of San Bernardino and San Jacinto. Loma Linda is in a strategic position between beaches, mountains, and desert. It covers an area of 195,500 hectares and has an altitude of 355 m above sea level and a Mediterranean climate with an average annual temperature of 17.4 °C ^{[48][58][80][82]}[39,65,80,81]. The population is about 25,129 inhabitants ^[83][75]. It is predominantly a Seventh-Day Adventist community ^[84][82]. Loma Linda Adventists have found ways to maintain a consistent program of physical activity and other healthy habits ^[80][81]. Exercise, a vegetarian diet, not smoking, eating nuts, and having social support have been shown to predict longevity among Adventists ^[85][116]. They are united in this doctrine of wellness, where the difference is not so much the physical environment as the religious and social environment. Adventists adhere to a set of behavioral pillars that they believe will bring them closer to God. They are associated with religious devotion ^[80][81]. Another mechanism by which religion may be associated with physical health is through social support. Social integration is facilitated by religious organizations: religious groups also often have formal assistance programs for those with problems with finances, activities of daily living, or major life transitions ^[86][84]. Finally, religious communities regularly bring together people with shared values, commitments, and goals. This helps create a sense of connectedness and support ^[86][84].

3. Conclusions

Cilento and the LBZs share several common factors, including a hilly altitude (ranging from 355 to 600 m), a mild climate throughout the year (with temperatures between 17.4 and 23.5 degrees Celsius), traditional professions such as agriculture and animal husbandry, a predominantly Mediterranean or plant-based diet, and typical recipes based on legumes, tubers, vegetables, and extra virgin olive oil. Additionally, strong intergenerational family relationships, religious devotion, and the desire to maintain social relationships within the community are also prevalent. Given the similarities to Cilento, one may wonder if this is an LBZ waiting to be discovered. Lessons learned from this discovery could be applied to the general population to protect them from chronic non-communicable diseases and help slow the aging process.