Stella McCartney has urged people to go and see a documentary about the food industry so they could make "responsible decisions" about the products they buy.

The fashion designer, a committed vegetarian, took to the red carpet to co-host the UK premiere of Food, Inc, which examines food production and the corporations dominating the industry.

Stella, daughter of former Beatle Sir Paul McCartney, said the film did not specifically focus on the meat industry, but said many consumers would re-think their choices on buying meat after watching the documentary.

She added: "Once you've seen the film, you'll be educated to know how to make responsible decisions about what you buy.

"At the end of the day, the biggest way to let these corporations know you don't want this product and deserve a better product is by stopping demand."

Asked what aspect of the film she was most shocked by, she said: "More just the kind of globalisation of the food industry and how there's five major players that provide all the food and it's kind of terrifying.

"It's a scary film. It's so important to see it if you can."

Director Robert Kenner said he hoped the film, which has been nominated for an Oscar, would make people more aware of what they're eating.

"There's this myth that our food comes from a small little farm with white picket fence and a red barn. So much of it comes from mega factories and it's becoming more and more industrialised.

Actors Thandie Newton, Richard E Grant and Donna Air also attended the premiere, at the Curzon cinema in London's Mayfair, along with fashion designer Vivienne Westwood.