We get suprised when we can see a person, who is 80,90, or 100 years old, live plus doing things that they are not supposed to do.
I had the opportunity to talk with a centerian man and I asked him which has been the trick to continue alive and healthy, he answered me, the first thing is having a active life and he try to eat in the more natural way, it mean, he does not use artificial seasoning and those all things does the trick.
Another aspect we should keep in  mind relate to elderly people is when they get sick, we must be conscious that when one of them are sick, they do not feel well as a result they could perfoment sometime a hostility actitude, but it does not mean that they hate the people around them.