Our bodies are made up of trillions of cells, each cell a living entity in its own right, with minute organelles that function to keep the cell alive and allow it to do its job, in much the same way that our own organs keep us alive and functioning. The cells in the body are continually undergoing cell replication and division, whilst old cells are continually dying.
This continuum of regeneration is at the crux of both wellness and illness. When the cells have a healthy, harmonious environment to live in and receive all the nutrients they require in order to function optimally, they thrive, and when each cell divides it produces another healthy cell, collectively creating a body of vitality. Whereas when the opposite occurs i.e the cells are starved of the nutrients they require to function properly and their environment is toxic and unharmonious, cell mutations occur and disease sets in.
Moral of the story... look after your cells and they'll look after you, what goes around comes around.