As I am working as a doctor, I can meet lots of people, aged over 85. The physical condition of some people is still great, but that of others is not, of course. I always wonder, what makes these differences in the patients' conditions. One day, I asked one of my patients, who is about 100years-old, what makes him so healthy, and he replied "milk". Another one, who is about 94, replied "yoghurt". At that time, I simplistically came to the conclusion that dairy products make people healthy. But, wait a moment. There are lots of people who take dairy products, but live only a short time. So, dairy products are not only the things which decide life span. Thinking about that gave me another sleepless night!!