Bad bananas

My Nan is in hospital again. This time we think it's due to kidney failure. Above her bed are posters saying 'low potassium diet' and a list of foods that are big no no's. So why, when I ask my Nan what she has for breakfast in the hospital, does she reply 'grapefruit'? Grapefruit is on the list!

Lack of dietary training for the catering staff or am I just being nit picky?

We didn't have any grapefruits so here's a potassium fuelled couple of bananas instead.