7. The “Foodprint” of Dietary Choices

Some readers of my previous post (#6) may have noted the dates of my references — in 1982 and 2001 — and wondered whether such old statistics about the inability of available farmland to support heavy meat-eating are still valid.

The answer is:  Yes, the are, as evidenced by a study published last month (July 2016) in the journal Elementa:  Science of the Anthropocene, and which turned up on the internet just last week.  “Carrying Capacity of U.S. Agricultural Land:  Ten Diet Scenarios”  was authored by a six-person team headed by Christian J. Peters of Tufts University.  The researchers calculated the amount and type of farmland that would be needed for 10 different diets:  what Americans eat now, the omnivorous diet they would eat if they followed current USDA guidelines (which would have less fat and sugar but similar amounts of meat and dairy), five omnivorous diets that would use decreasing amounts of meat, and three vegetarian diets:  lacto-ovo-vegetarian (plant foods plus dairy and eggs), lacto-vegetarian (plants plus dairy), and vegan (zero animal foods).  Each diet was calculated to be nutritionally equivalent to the others in calories and nutrients.

The team’s findings were unequivocal:  the less meat is consumed, the more people our farmland could feed.  More specifically, U.S. agriculture could, if evenly distributed, provide adequate food for 1.3 times our 2010 population if we all ate meat — and double that, 2.6 times our 2010 population, if everyone were lacto-vegetarian.  In this model, grazing on/ using forage from non-arable land would not be an option for the vegan diet, so the lacto-vegetarian diet just edged out the vegan one for how many people the different diets could feed;  but in fact all three vegetarian diets were very similar in efficiency of farmland use.  And the correlation was direct between how much or little meat people’s diets would involve and how few or many people could be fed by U.S. farms.

The study was stark in pointing out that grazing animals on land that can’t be cropped could not supply a great deal of meat or even dairy foods, because such land is by definition not very productive (Parag. 4.1).  Certainly animals can be grazed on dry grasslands — but in order to do so sustainably and without damaging or desertifying the land, the numbers of the grazing animals must be kept low, or else they must be continually moved across very large areas.  And indeed, we should note that traditional nomadic cultures that grazed large herds sustainably on steppes had to be nomadic in order to do it, moving their herds and their encampments often and over considerable distances.

The study’s authors concluded (Parag. 4.2) that “the estimates of carrying capacity for each scenario suggest that dietary choices can greatly influence the ability of agriculture to meet human food needs.  Reducing meat in the diet clearly resulted in increased carrying capacity… the differences between the scenarios suggest that the dietary changes could free up capacity to feed hundreds of millions of people around the globe.”  They acknowledged that “Whether the windfall of such dietary change could be redistributed to those in need remains an important unanswered question” and this raises the issue of economic equity.  But that windfall will not be available to distribute in any way unless there is a major shift to plant-centric eating.

How people might learn to make this shift will be my next subject.

Louise “Gentle Bee” Quigley


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