What is the minimum age required to die of old age?

People under 78 years of age are not allowed to die of old age, and must, if they insist, die of some disease, or tragic accident that cut short their life. Of course, people over 78 years of age will die of some disease or tragic accident but we don't say that cut short their life, nor do we say they die of old age. We simply say it was a senseless tragedy and he or she will be missed. There are some people who use fake birth certificates in order to die of old age while younger than 78 but most people would prefer to die of old age legally and do their best to live long enough to die of old age.