In the first article of this series I talked about the French diet, and the Japanese diet is almost the polar opposite. Most of the foods that are staples in France – cheese, red meat, bread, butter – are consumed rarely in Japan, if at all. While France is known for their high-fat diet, Japan has one of the lowest-fat diets in the world, with meals built primarily on soy, fish, vegetables, and white rice. (1)
The Japanese have maintained one of the highest life expectancies in the world, and have been featured on many lists of the world’s healthiest countries. Public health experts hold the Japanese diet in high esteem, second only to the venerable Mediterranean diet. So what can we learn from the Japanese?
The Asian Paradox
One of the most defining characteristics of Japanese cuisine is the ubiquitous presence of white rice. In Japan, white rice is almost always served for two meals per day, and will commonly be featured in all three. (2) When ‘Paleo’ was still synonymous with ‘low carb,’ many wondered about the Asian Paradox – how can Asians eat so many refined carbohydrates and stay lean?
But now that ‘safe starches’ have become more widely accepted, it doesn’t seem like so much of a paradox. You know my take on the matter: not everyone does well on starch, but many people do, and adding more starch can often give people more energy and help them achieve their weight loss or other health goals. Starch has been part of the human diet for a couple million years, and white rice is one of the most benign forms of starch available. Plus, Japan’s high consumption of white rice means they eat significantly less wheat than most modern countries, which is probably a good thing.
What about all that soy?
You know I’m not really a fan of most modern soy foods, but one soy food that probably does deserve its badge of honor is natto. It’s a slimy soy ferment that I find somewhat disgusting, but it’s the single best source of vitamin K2 out there, and the fermentation process does appear to reduce the harmful compounds in soybeans. (3)
Traditionally, natto was used as folk medicine for heart disease and other ailments, and modern science is on its way to proving that traditional wisdom correct. (4) It turns out there’s a unique fibrinolytic enzyme in natto that scientists call nattokinase, which is being studied for use in treating atherosclerosis, stroke, hypertention, and other related diseases. (5) Studies have demonstrated its ability to directly break down the fibrin in blood clots, as well as its ability to activate the body’s natural fibrinolytic enzyme – plasminogen. These actions result in decreased plaque and lesion formation, and decreased formation of blood clots that could later cause a heart attack or stroke.
One neat thing about studying traditional diet patterns is noticing how the interactions between specific foods can help make the diet work as a whole. One concern about soy is that it’s a goitrogen, and can interfere with iodine uptake and use by the thyroid. (6) But while Japan is undoubtedly one of the top soy consumers (and not all of the soy they eat is fermented), they also have the highest iodine intake in the world thanks to their seaweed-rich diet. (7) One study shows that the Japanese have a unique ability to digest seaweed because of their gut bacteria, so they can eat more of it without experiencing digestive distress. (8) The high concentration of iodine in the Japanese diet likely goes a long way in protecting them from these negative effects of soy, and proves how important context is when evaluating a food.
The lesser known Japanese staple
The media has latched onto fish, green tea, and soy as the trifecta behind Japan’s slim, long-lived population, but one thing they rarely mention is soup. We know how beneficial bone broth is, and studies have found that soup consumption is inversely correlated with BMI and circulating leptin levels. (9) But many people don’t realize that besides rice, soup is often considered to be the most important food in Japan. (10) Broth for the soup is usually made with sardines or other fish simmered with seaweed, resulting in a mineral-rich stock to which other ingredients (such as miso) can be added.
In the traditional Japanese diet, some form of soup is served with every meal. And although Japan is slowly adopting a more Western diet, a study conducted a few years ago found that the Japanese still eat soup an average of 7.6 times per week. (11) This is certainly more than most people manage, and it’s more than three times the average weekly soup consumption of France.
Soup is a staple in other Asian countries as well. Vietnam is known for serving soup with every meal, and traditional Vietnamese pho is famous for its gelatinous beefy broth. (12) In Korea, soup is recognized as a healing food and was always given to women after they gave birth, which is why this recipe is called ‘Birthday Soup.’
What can we learn from the Japanese?
In addition to reaffirming the merits of bone broth, I think the Japanese diet shows us how important context can be. For a metabolically damaged American, eating white rice at every meal might cause problems, but for the Japanese, it provides a safe source of carbohydrates that complements their traditionally nutrient-dense diet. And although they do eat soy, it’s not as worrisome in the context of their extremely iodine-rich diet and consumed alongside other traditional foods. And although I don’t think we all need to run out and buy a package of natto, the studies on its benefits reaffirm the value of traditional wisdom in making food choices.