An interesting contrast that arises from “Fed Up,” the new documentary pitched as the “Inconvenient Truth” for food that had its Boston premiere on Wednesday at the Harvard School of Public Health.

Amy Klobuchar (Minnesota) and Tom Harkin (Iowa) are Senate Democrats from neighboring Farm Belt states. Harkin is accorded sainthood status after decades-long efforts against childhood obesity. Of industry mouthpieces who come before him in committee and swear that, for example, that sugary beverages have no ill effect on children who drink them: “Sometimes I just want to ask: Do you have any shame at all? … How could these people sleep at night, knowing they were lying through their teeth? … How do they live with themselves?”

He also observes, “The Federal Trade Commission has less authority to regulate ads for kids than adults. You’d think it would be the other way around.”

But Klobuchar, who is included in the film’s closing graphics as one of a long list of voices who refused to be interviewed for the film, comes in for — as it seemed to me — a level of opprobrium slightly higher than she deserved, expressly because she was such a disappointment. As in, we expect Big Food to be this way, but you were supposed to be with us, with your female, progressive-leaning self.

What did she do? In June 2011, she wrote what might seem as a defensible comment to Agriculture Secretary Tom Vilsack: "I believe we must focus on increasing fruits and vegetables rather than decreasing specific foods that provide an important source of essential nutrients.”

Except, she was saying it in defense of pizza in school lunchrooms. Here’s the preceding sentence from that letter: "Tomato paste contributes dietary fiber, potassium — a nutrient of concern for children — as well as Vitamins A and C.” She didn't mention that it is laced with refined sugar, is a fairly processed food, and hardly anyone not promoting a commercial agenda would say that pizza makes a valuable contribution to children's nutritional needs.

Say, did you know that Schwan Food Co., the country's largest supplier of school-lunch pizzas, is based in Minnesota?

After the screening, producer Laurie David volunteered that she considers Klobuchar’s action “the most controversial part of the film.”