Carnegie Mellon University, a world-class research institution set on a lush, tree-lined campus in urban Pittsburgh, issued a hot-button press release late last year over an unlikely source: lettuce.
“Eating lettuce is over three times worse in greenhouse gas emissions than eating bacon,” wrote Paul Fischbeck, a professor of social and decisions sciences and engineering and public policy. “Lots of common vegetables require more resources per calorie than you would think.”
Carnegie Mellon researchers published their findings in Environment Systems and Decisions, a scientific journal.
The study claimed a diet rich in fruits and vegetables is surprisingly harmful to the environment. Why? The foods have high resource usage and greenhouse gas emissions per calorie.
Soon food bloggers and journalists responded, claiming the polarizing release was misleading.
So what’s the deal? Is lettuce harder on the environment than bacon?
Heck no. Not if you’re making an appropriate comparison. The key is the quantity.
This past spring, our friends at Modern Farmer reported a follow-up story that shed light on the study.
According to Modern Farmer, researchers at Johns Hopkins University wrote a detailed letter to Environment Systems and Decisions, claiming the study drew conclusions the data didn’t support:
Given that bacon and lettuce have drastically different caloric densities (4.68 and 0.15 kcal/g, respectively), a person would need to eat 22 cups of lettuce to match the calories in two slices of bacon. This comparison makes for an attractive headline, but relies on unrealistic assumptions about dietary substitutions.
Lettuce’s reputation as a planet-friendly leafy green has been restored. (Thanks, Johns Hopkins!) Good to know, since we’re huge fans of the stuff at the Co-op. (Don’t worry, bacon. We still love you, too.)
Shopping for lettuce? Here’s some tips from the Co-op pros:
To trust food, you need to know where it comes from.
Foodborne illnesses and bacteria once endemic to meat, like E. coli and Salmonella, have made their way to leafy greens, too. Since 2006, there have been huge recalls due to the contamination of spinach and lettuce.
One can’t assume the safety of local food. But if a grower is local, we can ask questions and see for ourselves how safely our food is being produced and handled.
Blue Ox and Crossroad
The Co-op sources lettuce from two amazing Upper Valley farms:
Blue Ox Farm is a small certified organic family farm in Enfield, NH, at the corner of Route 4A and Shaker Hill Road. It started with 2 acres of vegetables in 2002 and has grown to more than 16 acres in 2015, growing more than 30 crop families.
Crossroad Farm is a 60-acre family farm in Post Mills, Vt., nestled in the rich farmland near Lake Fairlee. Tim and Janet Taylor started the farm with 15 acres more than 35 years ago. “Our big garden became a small farm,” Tim once told Vermont Life magazine. “Our first farmstand was a card table.”
Shopping for Lettuce
Loose-leaf lettuce should have unbroken leaves. Check for wilting or spoilage of the leaves at the tip or base. Head lettuce should be crisp but give a little when squeezed.
Keep lettuce unwashed in a plastic bag in the refrigerator. Store away from apples, bananas, and pears, as they give off ethylene as they ripen, which will turn lettuce brown.
Wash lettuce just before you are ready to use it. Do not soak lettuce in water. (Water softens the leaves.) After you wash lettuce, spin it, drain it, or blot the leaves with a paper towel.
Tried lettuce on the grill? Hannah Brilling, Co-op nutritionist, and Emily Rogers, Co-op educator, put together an awesome video to show us how it’s done:
My good friend Jaime King, Co-op chef and foodie extraordinaire, wrote a great post about lettuce with his usual blend of wit, knowledge, and deep love and respect for food and nature. Check it out here.