It seems the 'five-a-day' message was first dreamt up on the fields of California in 1988.
Ken Kizer was director of the State Department for Health Services. He says that it wasn't a case, as some have claimed, of fruit and vegetable growers looking for new markets, but a mutually beneficial venture for industry and public health policy.
"It didn't originate from the agricultural community. It just so happens that when we reached out to them and pointed out this would help them, they got onboard and became enthusiastic partners."
He says the evidence behind the campaign was compelling: "Beginning in the mid and late 1970s, the evidence became quite clear about the role of diet in preventing cancer and heart disease and other conditions."
Prof Tim Lang was advising the government when it was mentioned in the UK in the late 1980s.
He says: "I was called to a meeting at the Department of Health to discuss whether or not Britain should go down the route of using five-a-day.
"I was a bit sceptical, but I knew the evidence and the policy thinking that unless we got the population as a whole eating more fruit and vegetables, the enormous burden of diet-related health would carry on.
"We needed something."
Despite being officially adopted by the UK government in 2003, people are still eating an average of only three and a half portions of fruit and vegetables a day.
The five-a-day message has always been tied to health benefits, specifically that eating more fruit and vegetables reduces your risk of heart disease and cancer.
Studies over decades of people's diet and health have thrown new light on the associated health benefits.
Dr Eric Brunner is an epidemiologist at University College London.
He says: "What's turned out in the last dozen years or so is that, although some of these hypotheses have been confirmed, many of them have fallen over.
"The big one was fruit and vegetables in relation to the intestine.
"It turns out that dietary fibre is a protective factor so we're still on the side on unrefined cereals, but the fruit vegetables measured by vitamin C intake turns out to be completely unrelated to breast cancer and to colorectal cancer."
He says the five-a-day message still has value though.
"I would certainly not want people to throw the baby out with the bathwater because it is clear that eating unprocessed fresh foods is going to be a good idea, if only because it replaces the not so good nutrients".
