The letter follows reports that the Canadian prime minister has invested $95 million in a plant-based protein facility producing protein from peas and canola.
The money was invested in the Merit Functional Foods, by Agriculture and Agri-Food Canada, as a 10-year interest-free loan.
Speaking about the investment, Trudeau said: "As people around the world start eating more plant-based food products, we have an opportunity to bring together innovation in Canada and Canadian crops, and a chance to create good, well-paying jobs...
"This facility will be a world leader in plant-based proteins and will create good jobs in a fast-growing field. And by using 100 percent Canadian inputs, we will also support the farmers who produce canola and yellow peas used in Merit's products."
'Fiscally responsible move'
In response, veteran vegan and honorary director of animal rights charity PETA, Pamela Anderson has written to Trudeau to congratulate him on the move, and offer her help should he decide to drop animal products himself.
She wrote: "Your recent decision to invest another $100 million in our mushrooming plant-based industries fits that description - and that puts Canada on top when it comes to promoting a humane and healthy diet.
"Your fiscally responsible move not only creates good jobs for Canadians but also spares countless animals a terrible life and death. As COVID-19 has exposed serious health risks associated with factory farms and slaughterhouses, the world needs more sensible leaders like you, who are willing to embrace clean, compassionate, and clever food solutions.
"Were you to drop meat and dairy from your personal diet - which I so hope you will - I would be honored to be your mentor and to suggest some of the tasty, diverse vegan foods proudly produced in Canada."