There have been many studies into the Japanese diet due to the Japanese people living longer than almost any people from anywhere else in the world[i]. The traditional diet is full of vegetables both cooked and pickled, grains such as rice and buckwheat, fish and moderate amounts if soy and animal products and low amounts of dairy and fruit. This diet is low in calories and saturated fat but nutrient dense, particularly antioxidants and flavonoids including phyto-oestrogens.
Japan is a collection of 6582 islands and has a strong fishing culture which means the diet is full of fish. Okinawa, an island in South West Japan, has one of the highest populations of centenarians and has been designated as a Blue Zone by National Geographic magazine. The population of Okinawa (as studied in the Okinawa Centarian Study[ii]) have an exceptionably low rate of degenerative diseases related to age including cancer, heart disease, diabetes, Alzheimer’s disease. This has been attributed to the people of Okinawa adhering to the traditional Japanese diet and not being impacted by the modern Western diet which is higher in calories, saturated fat and processed foods.
Part of the health benefits of the Japanese diet have been attributed to eating foods that support gut health and the growth of beneficial bacteria. The Japanese eat lots of soy beans, particularly fermented ones such as miso and natto, and aduki beans. Natto is thought to be a powerful probiotic which has been shown to reduce IBS[iii]. The wide range of vegetables provides plenty of fibre which is a prebiotic and encourages the growth of beneficial bacteria which metabolise this.
The Japanese diet is high in nutrients that prevent cancer such as phyo-oestrogens in soy which prevent hormone dependent cancers such as breast cancer. Sushi and other Japanese dishes also include lots of seaweed which is packed with micronutrients and minerals such as zinc, calcium, magnesium, selenium and iron, and protein and fibre. Seaweeds contain a molecule known as fucoidans, which are potent anti-inflammatories and anti-viral molecules are important for good immune and cardiovascular health and may help to reduce blood pressure. They are also strong antioxidants which important for cancer prevention[iv].
Another important part of the Japanese diet is green tea, particularly matcha tea. Matcha tea contains polyphenols such as catechins which is interrupts new blood vessel formation from existing blood vessels[v]. Blood vessel formation (angiogenesis) is an important part of cancer growth and metastasis, and cardiovascular and other inflammatory diseases.
A large prospective study in Japan looked at nearly 80000 people for 15 years which demonstrated that the lifestyle including diet and socioeconomic factors including health insurance contributed to the longevity of the Japanese people. Three Japanese Ministeries have collaborated to create the Japanese Food Guide spinning top. Following this guide to eating has been shown to reduce early mortality rates, and cardiovascular disease and stroke and is recommended to increase longevity.
[i] Quality of diet and mortality among Japanese men and women: Japan Public Health Center based prospective study
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