How can some countries live to healthy old age when the citizens eat a lot of soy products?

Mulitfactorial: Healthy aging depends on multpile factors including eating a healthy and colorful diet(lots of fruti and vegetables, minimal meat and healthy fats), physical and mental exercise, staying socially connected and practicing preventative health. That is, identifying a medical problem early before it becomes more serious. Getting vaccinated for preventable illnesses. Genetics do play a role as well.

Soy is healthy.: Soy is actually a healthy item to incorporate into the diet. By adding soy protein and limiting animal sources of proteins, we cut the amount of saturated and trains fats from our diets. And soy has heart protective qualities as well.