According to Takeo Koizumi’s newsletter article below, power foods in the Edo period were as follows

Miso soup + tofu + natto + deep-fried tofu
These four types of soy foods were eaten. Soy has as much protein as meat. Triple protein intake. In other words, soy = meat, so if you drink three cups of this per day, you have consumed almost the same amount of protein as the daily intake of meat and other animal protein by modern people. And since soy has no cholesterol or fat, it is the healthiest food there is.

What are the seven main dishes of an ideal Japanese meal?
Root vegetables, leafy greens, fruits and vegetables, wild vegetables and mushrooms, beans and soybeans, seaweed, grains (rice and wheat)
There was no meat, fish, or eggs.
The reason why protein was obtained without taking meat or fish is that the protein content of beef and soybeans is exactly the same at 17%. Soy has no bad cholesterol. The body does not oxidize. Therefore, it does not age. There are many good things about soy.

Such a powerful vegetarian consumes a lot of “fiber,” which strengthens the intestines. The gut is so important to humans that it is called the second brain, and a gut strengthened with fiber will strengthen the immune system and make people live longer.

Such a powerful vegetarian consumes a lot of “fiber,” which strengthens the intestines. The gut is so important to humans that it is called the second brain, and a gut strengthened with fiber will strengthen the immune system and make people live longer.

CONCLUSIONS:
Power food from the Edo period to strengthen the intestines, enhance immunity and live longer.

Japanese Who Could Survive as Long as They Had Miso [Takeo Koizumi, Emergency Rations for the Wise (3)
https://koizumipress.com/archives/13415

Natto may prevent post-infection deterioration of new corona
https://www.newsweekjapan.jp/stories/world/2020/06/post-93653.php?t=1