A "radical rethink" of how the UK produces and consumes its food is needed, Environment Secretary Hilary Benn has warned.
He was speaking at the launch of the government's assessment of the threats to the security of what we eat.
The food supply was currently secure but population growth and climate change could have an impact, he warned.
Producers, supermarkets and consumers have been invited to suggest how a secure food system should look in 2030.
Some of the findings from the consultation are expected to be published in the autumn.
As well as launching the consultation process, the Department for Environment, Food and Rural Affairs (Defra) has published a scorecard-style assessment of the current state of the UK's food supply.
"It is to stimulate a debate within the UK on what a food policy should be, and how do we define and look at food security more broadly," said Defra's chief scientific adviser Professor Robert Watson.See assessment on state of UK food supply
"Food is absolutely essential, and over the past few years we did see a food price increase - not only in the UK, but across the globe," he told BBC News.
"We think it is time to have a debate with consumers, farmers, the private sector... on what the food policy should be for the UK.
"We are clearly food secure in the UK today," he observed. "We produce about 60-65% of our own food [and] import about 20% from Europe.
"So the [test] for us will be, as the Earth's climate changes, what will be the challenges not only in the UK but throughout the world?"
Environment Secretary Hilary Benn said while Britain was more self-sufficient now than it was in the 1930s and 1950s, everyone had to start thinking ahead about how to produce more using less water and less fertiliser.
He said last year's sudden jump in the price of food and oil, which most fertilisers are based on, was a "wake-up call".
"We saw last year when the oil price went up and there was a drought in Australia, which had an impact on the price of bread here in the UK, just how interdependent all these things are," he said.
"We have to feed another two and a half to three billion mouths over the next 40 to 50 years, so I want British agriculture to produce as much food as possible."
He also encouraged British consumers to buy more UK-grown produce and called for a re-think on best before or sell by dates to reduce waste.
Food for the future
Today's food security assessment focuses on six areas, including global availability, UK food chain resilience and household food security.
It assesses the current situation in each area, and the likely situation in 5-10 years time.
One sector identified as "very unfavourable" and showing no sign of improving is global fish stocks.
Yet other areas, such as the diversity of the UK's suppliers of fresh fruit and vegetables are deemed "favourable" and likely to improve even more.
In July, the Sustainable Development Commission - the government's environmental watchdog - warned that the current food system was failing.
In its report, the commission warned that the current approach was a major source of greenhouse gas emissions, and paid little attention to soil quality and water use.
Responding to the Defra publications, the British Retail Consortium said that any strategy had to be centred around consumers.
"Without their buy-in, no plan will work," said food policy director Andrew Opie.
"We do need a sustainable supply chain, but retailers do not need government statements to wake them up to these issues, they are already taking action.
"What we need is joined-up policy with government agreeing what it wants from food across all its departments and agencies."
See UK Food Security Assessment Summary in full [27.78KB]