Foods that improve physical ability

Ninjas were professional warriors that also engaged in spying activities. As spying activities require high-level physical and mental abilities, they always trained themselves to maintain their super-skills. They also knew a lot about the foods they ate. They researched the effectiveness of each ingredient and classified them in order to use them to their advantage.

Soy beans
Soy beans were eaten by Ninjas on a daily basis. There are 3 reasons why they ate soy beans.
Soy beans contain rich vegetable protein. Protein’s role is to build muscles and replenish skin. As meat was not commonly eaten in Japan at that time, soy beans were an important source of protein used to strengthen their muscles.
A ninja needed to be lean and agile. They were required to maintain a weight of less than 60 kilograms. Taking protein from vegetables was a smart way to control their weight.
Soy beans are effective in improving skin-condition as they are rich in omega-3 fatty acids, isoflavones and linolenic acid. Ninjas sometimes needed to disguise themselves when spying, and having clean skin was advantageous when trying to pass as a townsman, monk or even a woman.

Sesame
Sesame contains Vitamin E which slows aging and prevents graying-hair. It also has a large amount of unsaturated fatty acid which is effective in lowering cholesterol and preventing arterial stiffening. Ninjas made use of sesame in their daily meals. Sesame is used as oil or seasoning for rice and vegetables in Japanese foods.

Dried Squid
Ninjas tried to maximize their abilities by doing physical training and eating special foods. They ate dried squid to strengthen their jaws. This jerky-like food had a very hard texture and really needed to be chewed each time it was eaten which made Ninjas' jaws firm and strong. Believe it or not, clenching their strong jaws actually helped enable them to exert all their strength.