Seth has a hypothesis:

If you know anything about heart disease epidemiology, you know that Japan has the lowest rate of heart disease in the world. The usual explanation is high fish consumption. But other countries, such as Norway, also eat a lot of fish but don't have low heart disease rates.

My visits to Japan suggest to me that Japanese eat far more fermented foods than people in other countries, including Norwegians. If heart disease is due to infection, then it's clear that the immune stimulation provided by fermented foods helps fight infection. My umami hypothesis -- that we like umami, sour, and complex flavors to encourage bacteria consumption, which we need to be healthy -- began with a trip to Japan in 2008, when I noticed, in a food court, many types of miso for sale. Back in Berkeley, I started making miso soup. I was stunned how well it worked. All you needed was miso. No other flavorings. It was so easy and good I ate it every day. It was my first bit of evidence that fermented foods are different and better than other foods.

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