“After this hearing, I may be consulting that guideline,” Vilsack interjected dryly. The room erupted with laughter. Were Vilsack to consult that guideline, he would find that he is allowed up to two daily drinks. Were he female, he would be allowed one.

“The FDA would say he meets age requirements,” Burwell added, paradoxically squelching the only moment of levity in Wednesday’s house agriculture committee hearing. It was supposed to be a historic battle over the purview of dietary recommendations. But the evening prior, after months-long debate, the nutrition advocates bowed, wholly and deeply, to agriculture interests. In what they would later refer to as “the blog we put out last night,” Vilsack and Burwell wrote on the USDA website, buried at the bottom of a subtly titled post, that sustainability would not be a consideration in the final 2015 dietary guidelines.

For the first time ever, the expert panel had included in its recommendations some mention of sustainability, acknowledging that questions about human nutrition cannot be divorced from the logistics of how this nutrition is procured.

To take an extreme example, it would be of no use to tell people to eat a diet high in diamonds. It would be counterproductive to extoll the nutritional virtues of human meat. In practical terms, it would be irresponsible not to consider the emissions that accompany large-scale farming of animals (18 to 51 percent of all greenhouse-gas emissions, by various estimates, not to mention intensive water use) when recommending how much animal meat an entire nation of people should ideally consume.

Nutrition experts largely supported the concept. In Science last week, researchers led by Kathleen Merrigan captured the sentiment: “By acknowledging benefits of sustainability, the government would open itself up to greater demand for sustainability investments and would signal to consumers that such foods are preferred.”

Even the most fundamental nutrition science cannot be divorced from discussion of agriculture, many argue. Fish, for example, is more nutritious depending on how it's raised, notes Tom Brenna, professor of human nutrition and chemistry at Cornell University. Wild-caught fish is generally more nutritious than farm-raised fish, just as grass-fed beef is preferable to corn-fed, and it would be remiss not to mention this. Brenna was on the expert advisory committee. And based on a confluence of what is good for human bodies, available to people, and good for the planet (the continued existence of all human bodies), the committee concluded that plant-based diets are preferable to diets high in animal meats.

This did not sit well with many in the business of meat. “Some of the biggest critics of these guidelines are from industries that supply unhealthy foods and special interests with questionable credentials,” noted representative Jim McGovern of Massachusetts, during Wednesday’s hearing. He mentioned hearing from a former Enron executive who was trying to fund opposition to the proposed recommendations. “I don’t know what Enron knows about dietary guidelines, but there are powerful interests out there trying to challenge credibility, trying to question science.”