It is a claim that could put a dent in the green credentials of vegetarians: Meat-free diets can be bad for the planet.
Environmental activists and vegetarians have long taken pleasure in telling those who enjoy a steak that livestock farming is a major source of harmful greenhouse gases.
But research has shown that giving up meat may not be as green as it seems.
The Cranfield University study found that switching from British-bred beef and lamb to meat substitutes imported from abroad such as tofu and Quorn would increase the amount of land cultivated, raising the risk of forests being destroyed.
Production methods for meat substitutes can be energy intensive and the final products tend to be highly processed, the report, which was commissioned by the environmental group WWF, found.
The researchers concluded: ‘A switch from beef and milk to highly refined livestock product analogues such as tofu could actually increase the quantity of arable land needed to supply the UK.
Donal Murphy-Bokern, one of the report’s authors and a former co-ordinator at the Department of Environment, Food and Rural Affairs told the Times: ‘For some people, tofu and other meat substitutes symbolise environmental friendliness but they are not necessarily the badge of merit that people claim.’
But Liz O’Neill, of the Vegetarian Society, said: ‘If you’re aiming to reduce your environmental impact by going vegetarian then it’s obviously not a great idea to rely on highly-processed products.’
A spokesman for the WWF said it was important to remember that livestock produce large amounts of methane, a much more potent greenhouse gas than carbon dioxide.