Darling buds: how best friends keep us healthy and happy

Strong social networks have been shown to improve wellbeing, but what are the extra perks of having a really close friend? And why are women more likely to have one?

We met when we were five. I don't know how I would have managed without her." As children, Barbara Kastelein, from Ashford in Kent, and her best friend, nicknamed Tulip", both had alcoholic fathers. Their friendship was an escape from unhappy homes.

The best friends are now both 55 and their relationship is as solid as ever. Barbara says they are more like sisters - and still there for each other during tough times. When Barbara's father died, Tulip drove for hours to be at the funeral and to help Barbara empty her father's flat. I can't imagine life without her," says Barbara. She is my guardian angel."