'Was there something in the water, Charlize?'

Charlize Theron had "diarrhoea" for seven days during a charity trip to South Africa

The Oscar-winning actress set up her own organisation, the Africa Outreach Project, which focuses on sex education and HIV/AIDS prevention in her native South Africa, and while she admits the work is not glamorous, it is very rewarding and grounding.

She said: "I'm sitting on a toilet for seven days with diarrhoea. But it's the thing that puts everything into perspective....

"There's a part of me that will always be the South African who knows and realises how unbelievably fortunate I have been."

And while Charlize – who is a spokeswoman for Christian Dior – admits she enjoys some of the finer things in life, she will never go overboard because she knows what's important in life.

She added to the USA Today newspaper: "I'm completely spoiled - don't get me wrong - but I am not one of those people who needs another box of eye shadow. I only have two eyelids. There's only so much eye shadow that can go on two eyelids.

"I don't like a lot of stuff. I have a thing against excess."

• The Charlize Theron Africa Outreach Project is committed to reducing the prevalence of HIV/AIDS and sexual violence among African youth by supporting and collaborating with organizations that provide preventive education.

Its first project was in collaboration with Oprah Winfrey's Angel network, which provided lead funding to create a mobile health and computer clinic designed for improving the health and social development of Umkhanyakude district youth in KwaZulu-Natal province.

Its second project, in 2010, partnered with the ONEXONE foundation to break ground on an initiative called Home Field Advantage, which aims to build soccer fields - ironically, with clean water sources.