A study of this collected data shows that if we change our diet to comply with current guidelines, the result will be about 15 % less greenhouse gas emissions than our current eating habits produce. It would also lead to the improvement of several other environmental indicators.

This means eating less red meat, dairy products, sugary drinks, sweets and snacks and more whole grains, nuts, fruits and vegetables. (by Anne Wennberg, University of Oslo, more at phys.org)