People choose to follow vegan diets for any number of reasons, but a few stand out. For some, it's due to animal welfare concerns; for others it's for the health benefits—numerous recent studies linking meat to cancer may be building concern. Then there are environmental factors—a diet without carbon-intensive meat is frequently argued to be better for the planet.
But a new study suggests that if you're going vegan to try to save the world (and humanity), there may be a better way… and it doesn't require that you sacrifice Brie.
According to the study—published in the journal Elementa, which studies the science of the anthropocene, or how humans affect the earth's climate—it turns out a vegan diet is more land-intensive than a vegetarian diet that include dairy, as well as vegetarian-leaning (but still omnivorous) diets.
In light of growing global populations, the study examined the amount of people that could be fed from US farmland depending on what types of diets they followed—in other words, what the "carrying capacity" of agricultural land was based on what people ate. Researchers looked at current farming practices and what land requirements would be necessary if everybody went vegan, vegetarian, or omnivorous to various degrees. The omnivorous diets followed the USDA guidelines for healthy eating for a certain number of meals and went lacto-vegetarian (consuming dairy, but no eggs) for the rest.
It turned out that the land could feed the most people if the population followed either a lacto-ovo vegetarian (dairy and eggs permitted) or simply lacto-vegetarian diet, or if they followed omnivorous diets that were omnivorous 40 or 20 percent of the time and vegetarian the rest. A vegan diet placed as the fifth-most efficient in terms of agricultural land carrying capacity.
The discrepancies are due to how specific agricultural practices make use of land. The study examined the three types of land use that define modern agriculture: land used for growing crops, land used for perennial forage crops such as hay and grain that could be used to feed livestock, and grazing land. Perennial forage crops are necessary on all but the best agricultural land whether or not you plan on raising livestock—sustainable land management requires hay or pasture grown in rotation with annual crops to maintain quality arable land year-over-year. Grazing land—for example, non-arable grasslands or woodlands—isn't suitable for growing food.
So in trying to maximize land use, a vegan diet doesn't make use of grazing or perennial cropland, whereas diets that allow for a degree of animal husbandry do. The best way to make the most of the land is to eat vegetarian and include dairy but not eggs; the second-best is a vegetarian diet with eggs and dairy, followed by omnivorous diets that are lacto-vegetarian (no eggs) 80 and 60 percent of the time.
The carrying capacities of these diets were massive improvements over the current land use that supplies our Western diet. Any of the aforementioned diets could increase the amount of food grown from the land by more than 200 percent, but it may come as a surprise to some that a vegan diet ranked so poorly.
For some added perspective, just cutting discretionary calories from current diets would feed an additional 19 million people.
Other recent research has suggested a vegan diet might be best for the planet in other ways, namely in reducing food-related greenhouse gas emissions by as much as 70 percent from current levels. But if we all plan on sharing this rock beyond our lifetimes, we'd better figure this whole thing out. For now, you'll find us by the cheese plate.