Maggie Gyllenhaal works in an organic food store as a shop assistant in her spare time.

The ‘Dark Knight’ actress and her husband Peter Sarsgaard are so passionate about eating healthy food that they lend their spare time to a co-operative supermarket near their home in New York City, where all the employees are volunteers and receive heavy discounts on their groceries.

She explained: ‘’We work at this place, it’s a co-op and if you work there you get cheap groceries. I don’t do it because you get cheap groceries, I do it because they have incredible food and incredible produce. You cannot just pay to be a member, you have to work there.

‘’My husband works a lot of my shifts for me because he’s really serious about it, but I do the odd shift. It’s three hours and 45 minutes once a month, which seems like nothing, but for professional New Yorkers it’s hard to figure out.’’

The 35-year-old star - whose brother is actor Jake Gyllenhaal - prefers to remain inconspicuous while working at the supermarket and has recently transitioned from floor staff to a job in the basement.

She told Empire magazine: ‘’I’ve worked in the office but I have a new shift now, down in the basement where you put the apricots in the little bags. You get in trouble really easy there. They have a lot of rules and I’ve missed shifts, but I try. I try.

‘’I’ve worked in the office before and people call up and lie!’’