Woody Harrelson is obsessed with buying kale.

The eccentric actor and keen environmentalist is a huge fan of the roughage - a form of cabbage which is good for aiding digestion - and enjoys it with most meals.

His 'Seven Psychopaths' co-star, Colin Farrell, said: ''He does buy kale like it's going out of fashion. He's off buying kale every second.''

Despite Woody being famed for his activism, Colin said he was not outspoken about his beliefs on set.

He said: ''There was no finger wagging, no preaching, at all. He was just cool as a cucumber. The coolest f***er around.''

Woody, 51, lives a very healthy lifestyle, including cutting out sugar, flour and dairy and he doesn't eat meat.

He loves smoothies and has previously described his favourite smoothie, saying it contains berries, kale, kiwi, plum, pineapple, cinnamon and hemp seed.

Woody also doesn't wear clothes made of synthetic materials or cleaned at normal cleaners, saying: ''Even sleeping on sheets in hotels washed with all these detergents -- I mean, I literally get nauseous.'' He also refuses to talk on a cell phone.