During a phone call with her son Joe Bennett, from Folkestone in Kent, Foreman said the prisoners she was with were “so resilient, so tenacious”.
Ordinary Iranians have “an amazing culture of graceful kindness and absolute generosity”, she said.
Foreman says the prison’s daily menu of “rice and gristle” is “repeated every single week”.
She said she had been able to buy basic goods, such as bread, flour and sugar, from a shop inside the facility, although it has been shut in recent days.
Foreman says she has started running round the prison’s concrete courtyard, which makes a lap of 55 metres (180 ft).
“It’s repetitive, but sometimes repetitive is good. You can sort of switch off a little bit.”
She also spends her time studying psychology and Persian (Farsi), according to the family.