You're probably sick of your vegan friends telling you this, but it turns out giving up meat and dairy really is the best thing you can do for the environment.

A new study which looked at the impacts different types of food production has found even the most environmentally friendly meat is worse than the most damaging plant food.

"A vegan diet is probably the single biggest way to reduce your impact on planet Earth, not just greenhouse gases, but global acidification, eutrophication, land use and water use," lead researcher Joseph Poore of the University of Oxford told the Guardian.

"It is far bigger than cutting down on your flights or buying an electric car."

The study looked at data from nearly 40,000 farms in 119 countries, and 40 products which account for 90 percent of the world's food.

While meat only provided 18 percent of calories and 37 percent of protein eaten worldwide, it used 83 percent of farmland and produced more than half of the agriculture sector's emissions.

Even the most efficiently produced beef took 36 times more land to produce than peas, and created six times the emissions.

And don't think you can just limit yourself to fish - the research found fish farming, which accounts for almost all the fish eaten in the West and two-thirds in Asia, had a much bigger impact than was previously realised.

"You get all these fish depositing excreta and unconsumed feed down to the bottom of the pond, where there is barely any oxygen, making it the perfect environment for methane production," said Mr Poore.

Methane is a particularly harmful greenhouse gas.

Mr Poore told the Guardian he wanted to know if there were choices meat-eaters could make to reduce their damage to the environment, but realised it was a no-brainer to give it up altogether.

"I have stopped consuming animal products over the last four years of this project. These impacts are not necessary to sustain our current way of life. The question is how much can we reduce them, and the answer is a lot."

The study was published in the journal Science.

Newshub.