A nutritional comparison of leading diets
Mediterranean and Okinawan diets have been hailed the best of the best, and interestingly share a key nutritional feature with the increasingly popular vegetarian and vegan diets.
According to the World Health Organization (WHO), optimal diets have one thing in common: They are wholefood and plant based. ©Shutterstock/Ollyy
Although these diets may look different from the outside, similarities are revealed in the nutrition science behind them. The six essential nutrients1 can be found in many different foodstuffs, therefore the ideal diet can be an endless number of dietary combinations. According to the World Health Organization (WHO)2, optimal diets all share a common, important feature in that they largely comprise fruit, vegetables, wholegrain cereals, pulses, nuts and seeds. In short, they are wholefood and plant based3. Plant foodstuffs are rich in vitamins, minerals, fibre and phytonutrients, which not only support a functioning metabolism but prevent and fight lifestyle diseases such as cardiovascular diseases4, type 2 diabetes5 and some cancers6, that are major causes of death globally7.
The Mediterranean diet
While there is no single ‘Mediterranean diet’, countries such as Spain, Greece, Italy, France, Turkey and Lebanon have traditionally eaten an abundance of plant foodstuffs, moderate amounts of fish, eggs and dairy products, and small quantities of red meat. The generous intake of olive oil and regular but small amounts of red wine make this diet unique. Olive oil replaces saturated fats8 with monounsaturated fats while additionally providing beneficial anti-inflammatory compounds9. Red wine adds polyphenols, strong antioxidants acting alongside other phytonutrients from fruit, vegetables and pulses, which protect cardiovascular health10.
The population of the Japanese island of Okinawa is famous for having one of the longest life expectancies in the world. As the old Okinawan saying goes, “At 70, you are still a child; at 80, you are just a youth; and at 90, if the ancestors invite you into heaven, ask them to wait until you are 100 and then you might consider it.” The traditional diet of this Blue Zone11 consists of over 95% whole-plant foodstuffs, primarily native purple sweet potatoes plus small to moderate amounts of rice, cereals, pulses, other fruit and vegetables, fresh herbs and spices, fish, tofu, fermented soya foodstuffs, and occasionally pork. Of interest is the practice of ‘hara hachi bu’, a habit of only eating to 80% fullness. This restricted intake, along with a proper ratio of fats and phytonutrients, are the suggested reasons for the low occurrences of inflammation and chronic disease in this population and for its increased sense of wellbeing12.
Instead of being determined by geography, vegetarian diets may be chosen for ethical or environmental reasons, religious beliefs, taste or affordability. Large communities follow this dietary pattern, such as Hindus, Buddhists, and Jainists. While excluding red meat, poultry and often fish, most will still consume dairy products and eggs. Lack of protein is often unnecessarily feared as it can be readily sourced from dairy products, eggs, pulses, nuts, tofu and soya foodstuffs. Iron is a little trickier to come by but requirements can be met by consuming wholegrains, prunes, dried fruit, pulses, nuts, seeds and leafy green vegetables. Not surprisingly, with a high intake of low-kilocalorie but nutrient-dense plant foodstuffs and a balanced fat supply, the vegetarian diet has been associated with health benefits ranging from preventing and managing type 2 diabetes13 to decreasing the risk of certain cancers14. The Seventh-Day Adventist community in Loma Linda, California (another Blue Zone) is the most well-known studied example.
Compassionately and ethically motivated, vegans exclude all animal foodstuffs and by-products including dairy products, honey and gelatin. Despite obtaining all the plant-related health benefits described above, there is little evidence of the health benefits of a vegan diet. Some nutrient needs may be hard to fulfil, meaning a vegan diet must be varied, well planned and supplemented if it is to meet nutritional guidelines. Iron, protein and zinc are present in a variety of plant foodstuffs, while calcium can be found in, tofu, almonds, pulses, leafy green vegetables, different kinds of fortified juices and non-dairy milk, as well as in breakfast cereal. Vitamin B12 can only be obtained from supplements or fortified foodstuffs.
It is also important to remember that taking pleasure in cooking and eating at home, enjoying sharing a meal with others, and not overeating are also vital parts of a healthy diet. While there is no such thing as one best diet to suit everybody, the healthiest patterns will always be nutritionally balanced and plant based. It is easy then to see why fad diets, which cut out one or more nutrient groups, cannot actually maintain their health claims for very long. Fortunately, the principles of a healthy diet are universal and adaptable to different cultures, individual preferences and the availability of local foodstuffs.