UK fish stocks have depleted
The government should think again about advising people to eat fish twice a week, a committee of MPs has said.
They said falling fish numbers were a "serious cause for concern" and might not be sufficient to meet that demand.
The environment, food and rural affairs committee also said the UK should grow more fruit and vegetables to help avoid future global food shortages.
But the committee warned care must also be taken to limit the impact of food production on the environment.
Government advice is for people to eat two portions of fish a week - one of which should be oily fish, rich in omega 3 fatty acids - although most people do not do so. Fish and shellfish are sources of proteins, minerals and are low in fat.
But a European Commission report in April warned 30% of EU fish stocks were beyond safe limits.
In a report published on Tuesday, the Efra committee said: "The current state of many fish stocks is a serious cause for concern."
It says the government "should consider the wisdom of continuing to advise consumers to eat at least two portions of fish a week at a time when the ability of the marine environment to meet this demand is questionable".
The government and fishing firms should be promoting little known types of fish and shellfish to eat instead.
The committee also said the UK must not "bury its head in the sand" and had a "moral duty" to do more to boost food production - to feed an extra 2.5bn people in the world by 2050.
It says the government should look at why relatively small amounts of food and vegetable are produced in the UK and how much that would rise by if everyone followed the "five a day" advice.
More work is needed on how to how to balance meat production with animal welfare and greenhouse gas emissions, the report says.
"UK consumers buying meat and dairy products should be encouraged to consider the environmental, as well as the health, impacts of their choices," it adds.
'Lack of understanding'
And it says people should be encouraged to grow their own food as a way of "reconnecting" them with food production - children should be better educated on the issue and councils should be made to publish plans about how they plan to increase allotments in areas where there is high demand.
The report noted that the UK food supply chain was run by the private sector but several witnesses told the committee there was a "lack of understanding" at Defra about how it operated. The department needed to spell out how it would address this, the MPs said.
Tesco executive director Lucy Neville-Rolfe told the committee "a lot of people in this country need cheap food" and it had to be affordable but the NFU trade union said many farmers were finding it hard to turn a profit in producing food.
The committee said: "Food must be affordable to the consumer, but its prices must also make it worthwhile to produce in the first place. An agricultural system must be profitable to be healthy."
It also said the potential of genetically modified crops should be explored further to see if they can play a role in boosting food supplies up to 2050, and beyond.
Its chairman, Michael Jack, said: "If people go hungry then political stability goes out of the window. This is a key lesson that Defra must learn from last year's food price hike when some countries ran short of food.
"What happened showed just how fine the line is between full supermarket shelves and empty stomachs."
Environment Secretary Hilary Benn said the government would soon publish a "comprehensive assessment of food security" and plans to assess the impact of food production.
He said: "Research and development lie at the heart of innovation in agriculture and that's why overall Defra, the BBSRC (biotechnology and biological sciences research council) and the industry last year invested more than £150m on research to support food and farming."