top of page

Eating your way out of the COVID-19 pandemic: clues from the traditional Japanese diet

#japanesefood #healthyeating #coviddiet #coronadiet #seaweed #greentea #fermented #herbalmedicine


The traditional Japanese cuisine, one of the healthiest food traditions of the world

Since the outbreak of the COVID-19 virus, research into potential prevention and cures for this seemingly intractable disease has become an urgent global priority. Given the ‘abnormal’ behaviour of the COVID-19 virus, it is apparent that conventional medical solutions may have limited capacity to control the disease. So, the question is whether our diet may offer alternatives in curbing the spread and alleviating the symptoms of COVID-19 infection.


As with many long-lived cultures, the history of Japan could well be described as one of an ongoing battle with epidemics. The Tenpyō smallpox epidemic of the 8th century wiped out one-third of the nation’s population at the time. As the imperial capital of Kyōto enjoyed its glory days between the 9th to 12th centuries, the nation was repeatedly ravaged by epidemics, famines, earthquakes, volcanic eruptions and weather calamities—which finally led to Japan spiralling into the warlike world of the samurais between the 13th and 16th centuries. Epidemics and natural disasters continued to shape Japanese history until relatively recent times, including a cholera epidemic in Edo (modern-day Tōkyō) in 1858, to which a quarter of the city’s one million inhabitants succumbed.


Kyōto’s refined culture belies the often calamitous conditions it developed under

Curiously though, these epidemics and calamities also contributed to the blossoming of Japanese culture as we know today. World-renowned cultural heritage such as the Tōdaiji temple in Nara (housing the Great Buddha statue), the Byōdō-in temple in Uji (featured on the reverse side of the Japanese 10-yen coin), the Gion Festival of Kyōto, and the Sumida River Fireworks Festival of Tōkyō all originated out of people’s wish for the suffering to end. The Japanese tea ceremony and garden traditions evolved, in part, as a form of diversion from the uncertain everyday life during the ‘Warring’ period of the 15th and 16th centuries when disease—apart from warfare, natural disasters and famines—was rife (see my June 2020 article on Japanese tea gardens https://www.deeplyregionaljapan.com/post/japanese-roji-a-garden-path-to-your-mind-and-spirit-part-1).

Byōdō-in temple in Uji, Kyōto, Japan (photo credit: Fumihiko Ueno, https://commons.wikimedia.org/w/index.php?curid=53772018)

Epidemics also influenced Japanese architecture. ‘Shinden-zukuri’, an architectural style for aristocratic residences that developed around the 10th century (Byōdō-in temple mentioned above is a fine example), features a number of ingenious designs aimed at curbing the spread of infectious diseases. The residences consisted of a collection of buildings separated by open corridors and courtyards to ensure adequate ventilation in every part. Inside, layers of removable screens and partitions divided the buildings into sections and rooms, and there were multiple step-ups in floor levels—with the uppermost floor level in the innermost part of the building being reserved for those with the highest social status, while all others were restricted to the lower and outer parts of the buildings.

An artist’s impression of an inner room in a ‘shinden-zukuri’ residence of the Heian period (8th to 12th centuries) showing the use of removable screens and floor-level changes (image source: https://winddorf.net/archives/04042901.html)

The overall effect of the ‘shinden-zukuri’ design was to reduce the risk of disease being transmitted through the air, particularly from those of lower social status—who were more likely to be carriers of disease. The rooms forming the living quarters of the nobility were quite small, so as to limit the number of people in each room and to physically distance members of the household across multiple rooms—as an additional precautionary measure. (Sounds all too familiar today in our ‘COVID-19 world’, doesn’t it?)

The room in the previous image with the ‘misu’ (a type of matchstick blind) lowered, allowing adequate ventilation while providing privacy and a barrier to inflow of air from the outer parts of the residence (image source: https://winddorf.net/archives/04042901.html)

For a short educational video clip (in Japanese) by Japan’s national broadcaster NHK showing a model of ‘shinden-zukuri’ architecture, visit https://www2.nhk.or.jp/school/movie/clip.cgi?das_id=D0005403019_00000.


Looking through historical records, it becomes apparent that the Japanese over the centuries also recognised the importance of diet in overcoming disease, in a similar vein to the ancient tradition of food therapy in Chinese medicine. Many texts have been written on specific foods for preventing and treating a range of diseases, and the knowledge was disseminated to the general public in some novel ways such as ukiyo-e (woodblock prints) and kabuki theatre.

‘Mashin yōjō no den’ (1862), a woodblock print by the 19th-century ukiyo-e artist Yoshitora Utagawa outlining the dietary treatment of measles (from the collection of the National Diet Library of Japan, Tōkyō)

With the current COVID-19 outbreak, Japan’s remarkably low casualty rate in comparison to most other countries has puzzled the medical profession, especially given that Japan has the highest proportion of aged population in the world, their cities have some of the highest population densities in the world, and the nation did not implement strict lockdown measures. Many theories have been put forward, including Japan’s policy of mandatory BCG (Bacillus Calmette-Guerin) vaccination against tuberculosis, the almost obsessive hygiene habits of the Japanese, or simply the genetic make-up of Japanese people. However, several lines of evidence point toward the Japanese diet as a potentially important factor.


The Japanese diet is unique among all food traditions in the world in the amount and variety of seaweeds used. An interesting insight is provided by how Japan fared comparatively well during the ‘Spanish flu’ outbreaks of 1918–1921 compared to most of the world—with a mortality rate of around 1% compared to the global mean of 3–5%. Even more interesting is the fact that, within Japan, the casualty varied immensely between different regions, with the lowest rates often coinciding with areas with the highest seaweed consumption.


School students wearing masks during the Spanish Flu outbreak, Tōkyō, February 1919 (photo credit: Mainichi Shinbun, https://commons.wikimedia.org/wiki/File:1919FluVictimsTokyo.jpg)

Seaweeds, especially of the brown-coloured varieties such as konbu, wakame and hijiki, are especially rich in fucoidans, a type of carbohydrate. Fucoidans have been scientifically proven to boost immunity, suppress tumour growth, and assist in maintaining circulatory health. Recent research also indicates that fucoidans are effective in preventing the so-called cytokine storm (see https://pubmed.ncbi.nlm.nih.gov/30797011/; https://pubmed.ncbi.nlm.nih.gov/30347679/)—when the body’s immune system ‘goes into overdrive’ in response to, for example, an infection—a major cause of serious complications in both the Spanish flu and COVID-19 outbreaks.