Residents of Okinawa, the southernmost region of Japan, are known for their long average life expectancy, high numbers of centenarians, and accompanying low risk of age-associated diseases. The long lifespan in Okinawa is generally attributed to a healthy lifestyle, particularly the traditional diet, which is low in calories yet nutritionally packed, especially with phytonutrients in the form of antioxidants and flavonoids.
According to research, diets related to a reduced risk of chronic diseases are quite similar to the traditional Okinawan diet, abundant in vegetables and fruits (therefore phytonutrient and antioxidant rich) but low in meat, refined grains, saturated fat, sugar, salt, and full-fat dairy products. These features are likely contributing to a decreased risk for cardiovascular disease, some cancers, and other chronic diseases through multiple mechanisms, including reduced oxidative stress.
Research shows that the traditional Okinawan diet is the lowest in fat intake, particularly in terms of saturated fat, and highest in carbohydrate intake, in keeping with the very high intake of antioxidant-rich yet calorie-poor orange-yellow root vegetables, such as sweet potatoes, and green leafy vegetables. Deeper analyses of the individual components of the Okinawan diet reveal that many of the traditional foods, herbs, or spices consumed on a regular basis could be labeled “functional foods” and, indeed, are currently being explored for their potential health-enhancing properties.
American gerontologist, Dr Craig Willcox, who has spent many years investigating Okinawan longevity and co-wrote a book, The Okinawa Program, summarized the benefits of the local diet: “The Okinawans have a low risk of arteriosclerosis and stomach cancer, a very low risk of hormone-dependent cancers, such as breast and prostate cancer. They eat three servings of fish a week, on average … plenty of whole grains, vegetables and soy products too, more tofu and more konbu seaweed than anyone else in the world, as well as squid and octopus, which are rich in taurine – that could lower cholesterol and blood pressure.”
Relevant features of the Okinawa diet:
- Calorie restricted diet:The diet of the Okinawan people is 20% lower in calories than the average Japanese caloric intake. Typically, their diet comprises no more than one calorie per gram and the average Okinawan has a BMI (Body Mass Index) of 20. Research has shown that by limiting the dietary energy intake below daily-average needs, calorie restriction improves health and slows the aging process in some animals like rodents.
- Anti-oxidant rich diet:Okinawa diet comprises mainly green/orange/yellow (GOY) vegetables, fruits, roots, and tubers. These foods are rich sources of anti-oxidant vitamins like vitamin-C, vitamin-A, and flavonoid poly-phenolic compounds like ß-carotenes, luteins, xanthins, and minerals like calcium, iron, potassium, and zinc.
- Low in fat and sugar:The Okinawa diet is low in fat and has only 25% of the sugar and 75% of the grains of the average Japanese dietary intake. Low-fat and limited sugar in the diet can definitely help prevent coronary heart diseases and stroke risk.
- Vegetarian and seafood rich:The islanders’ traditional diet includes a relatively small amount of fish and a higher amount of soy, low calorie vegetables like bitter melon, and other legumes. Almost no meat, eggs, or dairy products are consumed. Fish provide omega-3 essential fatty acids like alpha-linolenic acid(ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Besides being a very good source of protein, soy (in the form of tofu), contains health-promoting compounds like soluble dietary fiber, antioxidant tannins, and plant-sterols. Altogether, these phytonutrients offer protection against heart diseases, stroke, colon, and prostate cancers.
Advocates of Okinawa diet (The Okinawa Diet Plan, a book by Bradley Wilcox, MD, D. Craig Wilcox, PhD and Makoto Suzuki, MD), divide food items into four categories based up on their caloric density:
- The “featherweight” foods include foods that provide less than or equal to 0.8 calories per gram such as citrus fruits like orange; low calorie vegetables like spinach, cucumber, etc. These foods can be consumed without restriction.
- The “lightweight” foods comprise foods with a caloric-density from 0.8 to 1.5 calories per gram including certain fruits like banana and vegetables like potato. These should be consumed in moderation.
- The “middleweight” foods include foods with a caloric-density from 1.5 to 3.0 calories per gram, such as cereals like wheat, legume products, and lean meat. It is advised to consume only one moderate serving of these.
- The “heavyweight” foods comprise foods with 3 to 9 calories per gram (300-900cal per 100g). Many oils and fats, nuts, oil seeds and red meat fall in this category. These should only be consumed from time to time.