However, meat industry representatives are backing the appointment and Benn has denied his vegetarianism will affect how he represents the meat industry.
He said: "I am sure the farming community will judge me by what I do. I will wholeheartedly support beef, pork and chicken farmers and the meat industry in general and I very much look forward to meeting their representatives soon."
The NFU gave him its support as well, and told MTJ they did not believe Benn's "personal choice" would affect how he did the job.
Robert Forster, chief executive of the National Beef Association, said: "We can't judge him on what his personal beliefs or habits are, we have to judge him on what he delivers."