There are a few cultures that lead the world in life expectancy. Although overall lifestyle is important, diet in these cultures is a major factor. There remain a large percentage of Okinawans who reach 100 years of age. Centenarians in Okinawa typically have a BMI at around 20 through middle age (average BMI in the United States if 28-30, anything over 26 for men, 28 for women, is considered unhealthy, and a risk for heart disease). Consequently heart disease is uncommon compared to western cultures, and other diseases felt related to diet and obesity, are very low, including prostate cancer, colon cancer, and breast cancer.
People from the Ryukyu islands, the largest of which is Okinawa, have among the best life expectancy. Recently, men from Okinawa have seen a reduced life expectancy, felt by some to be related to adoption of a more western diet and lifestyle.
In the traditional Okinawan diet, the intake of calcium, iron, vitamins A, B1, B2, and C, and the proportion of energy calories from proteins and fats are significantly higher, while the intake of carbohydrates and salt were lower. The original Okinawan diet was typically also very low in animal products including seafood other than fish and dairy. The diet consisted of 30% green and yellow vegetables, soy (natto—fermented soy) and legumes, and smaller quantities of rice than in mainland Japan, which was substituted for with Okinawan purple sweet potato. Sugar and grain intake is low, and fish is eaten on average one-half serving daily. Pickled vegetables (probiotics) are regularly consumed.
Of interest, this eating style results in caloric intake approximately 30% that of the American diet. In the United States, 2000-2400 calories daily are recommended for the average younger adult, with moderate to active lifestyle. The nutrient rich foods consumed in Okinawa, allow for a lower caloric intake.
The Okinawan diet is frequently mimicked as a model for weight loss programs. Unfortunately, the Okinawan diet is difficult to adopt in the United States and other western countries. Even the soy products in the U.S. are at times felt to be unhealthy, due to phytoestrogens (plant based estrogens) and other chemicals. But the message is clear: eat fresh produce, small amounts of high quality meats, eat fresh wild caught fish, avoid grains (especially processed) and limit milk products.