Certainly. It's clear that some foods tend to have much higher emissions than others, both directly from their production and by using more land than other crops. If you can shift diets to some degree to some of those lower-emission foods, that can reduce emissions from agriculture.
That's sort of a demand-side approach, which the Intergovernmental Panel on Climate Change is getting more excited about, for example. It does seem like a really important component of the whole thing.
One possible approach to doing that would be through just changing what kind of food is served in schools.