A New You Every Seven Years?

I once heard that your body replaces itself every seven years what with shedding skin, growing new hair and cells dying and being replaced but how true is it?
'That old chestnut' said the medical researcher i asked who then went on to explain that if it was true nobody would ever age which my mirror shows each morning is abundantly not true.  
According to research, the body has 30 trillion human cells and around 330 billion of those cells are replaced every day while other cells renew each week and some, such as our muscles, renew every 70 years while some such as the ones in our brain, heart and eyes are with us for our entire lives.
Stomach and intestines typically last only up to five days, skin cells  rejuvenate every two to four weeks, hair has a life span of about six years for women and three years for men, the Liver renews itself with new cells every 150 to 500 days and  the cells in our bones takes a full 10 years and slow down as we age.
Despite all this regeneration, the average age of all our cells is about seven years (hence the Old Wives Tale) and the sad truth is that we still get old and die because of mutations every time our cells renew so if you think you're going to look young and beautiful forever, you'll will have to find the Fountain of Youth.