This article has been updated. It originally published on Jul. 29, 2023.
The average American eats around 180 eggs a year, which makes sense: Eggs are a versatile, delicious, convenient source of protein. One large egg has 6 of the 65-ish grams a 180-pound person needs in a day, and, like all animal proteins, it’s complete, meaning it’s got all the amino acids our bodies need to function.
Eggs present a sustainability paradox, however. What’s most sustainable for the chickens isn’t necessarily what’s most sustainable for the Earth in terms of emissions.
The labels you see on egg cartons indicate conditions as opposed to carbon. Egg production has the same pitfalls as other animal agriculture. Factory farms (technically, “Concentrated Animal Feeding Operations” or CAFOs) create a lot of water pollution and keep hens and workers in cramped and unsanitary conditions.
When it comes to straight-up emissions, eggs are about as good as animal products get. Producing 100 grams of egg-based protein generates 4.2 kilograms of greenhouse gas. By comparison, beef hits 35.5, shellfish 18.2, other fish 6, and tofu 2. Opting for free-range or pasture-raised options, however, comes with a small emissions trade-off: Caged hens produce more eggs and require less feed than those that are free to roam, which means conventionally-produced eggs have lower planet-heating potential than huevos that prioritize animal welfare.
As with all animal products, the best way to avoid less-than-savory issues is to eat less. (Check out our guide to egg replacers for the best swaps.) But, in the case of eggs, if your budget allows for a couple extra bucks a week, you can opt for varieties that come from more-humane producers. Here’s how to parse the labels:
Typical: Standard supermarket eggs
If a carton touts only grade, color, and size, you’re looking at eggs from factory farms. Words like “farm fresh” and “all natural” are meaningless. Cage-free represents a small shift from traditional wire cages to enclosed barns with little-if-any outdoor access, so it’s not much of an upgrade from CAFOs.
Good: Free-range
These come from hens that have “continuous access to the outdoors during their laying cycle,” according to the U.S.D.A. What’s not specified is what that outdoor space consists of, whether the birds actually get to it, and for how long.
Better: Pasture-raised
Outside in nature by day; in barns by night. There are still unknowns: The size of the barns and quality of the feed can vary enormously. There’s also no legal definition of pasture-rasied. So it’s best to look for other terms like Animal Welfare Approved, Certified Humane, or Global Animal Partnership to be sure the chickens were raised on pasture.
Best: Local, small-scale, organic, pasture-raised
Whether from the farmer’s market, a roadside stand, or a neighbor whose rooster wakes you at the crack of dawn, eggs from small, local, organic farms are the top option if you’re invested in doing what’s best for the chickens.