Only one trust in 10 is aware of where the food served to patients comes from, an investigation by the Countryside Alliance Foundation has found.
A total of 225 out of 267 trusts did not know what countries the food they served in their hospitals, clinics and centres originated from in 2009-10, freedom of information requests by the foundation reveal.
Findings also show that for the 37 trusts that did know where their produce came from, just 62 per cent of the food was British.
The top performer was Humber Foundation Trust, which operates 16 clinics, mental health centres and hospitals - 98 per cent of the food they served throughout 2009-10 was British.
At Liverpool Heart and Chest Foundation Trust, the specialist hospital served food that was 22 per cent British.
A poll from YouGov commissioned by the Countryside Alliance Foundation also revealed that 60 per cent of people think that hospitals should buy British meat or meat products, even when it costs the hospital more.
The charity is using its findings to call on the government to prioritise the purchase of British food and introduce a minimum British food buying standards policy for the NHS to address the lack of British food on the menu.
Countryside Alliance Foundation chief executive Alice Barnard said: “Although the current economic conditions are making life difficult for hospitals, the importance of buying high-quality British food should not be overlooked.
“Evidence has shown that investing in local produce means investing in higher quality food for patients, which in turn improves their recovery, and puts a little back into the local economy.
“The Countryside Alliance Foundation would like to see the government buying standards extended to hospitals, to ensure patients, producers and taxpayers are getting the best possible deal from the NHS.”