Eating Lettuce May Be Good for You—but Is It Good for the Environment?
A number of studies have said a vegetarian diet is better for the environment than the Standard American Diet, which piles on the meat, dairy, and processed foods. Yet a new study published in Environmental Systems and Decisions has found just the opposite to be true when people eat more fruits and vegetables.
The authors, Michelle Tom, Paul Fischbeck, and Chris Hendrickson of Carnegie Mellon University, looked at three dietary scenarios and measured their blue water footprint, greenhouse gas emissions, and energy use: SAD but with fewer calories, USDA’s recommended diet at current level of caloric intake, and reducing calories as well as switching to the USDA diet, “which support[s] healthy weight.” Surprisingly, they found that sticking to processed food decreased all three categories by about 9 percent—while the rest came with increases in the amount of resources used across the board.
The results are not because this is some skewed big food–funded study, but because the authors made a major departure from previous research in terms of what information they counted. While a majority of studies look only at calories consumed, these researchers looked at food waste throughout the food chain and added the lost resources to their final totals. And we waste a lot of food in the United States: Between 30 and 40 percent of the annual food supply, or 133 billion pounds of it each year, ends up in the trash. But not all foods are wasted equally. Perishable foods obviously have the shortest shelf life and are the most susceptible to waste.
Not only does meat not go bad while waiting in the field in the form of a living animal, but the product itself is often frozen after slaughter, giving it a reprieve from the spoilage that can occur during transportation from warehouse to grocery store. Fruits and vegetables, on the other hand, are both fresh and delicate. They have to remain in perfect condition on the tree or in the field, and they must maintain their good looks through their journey to the grocery store and while sitting in large displays as customers paw through them. If there’s a shiny and unblemished apple to be purchased, why would a customer spend the same amount for something with brown spots? Even dairy doesn’t have the same aesthetic standards as fruits or vegetables and is considered good until it literally spoils.
There are other considerations too, such as that California’s arid Central Valley produces two-thirds of the fruits and nuts in the United States and requires a lot of water to do so. That fish have the second-highest energy usage and greenhouse gas emissions of any category of food is in part because of the production of feed for farmed fish and the fuel usage of fishing vessels for anything wild-caught.
Not only is it wasted at a higher rate, but calorie for calorie, you have to eat a lot more lettuce to make a meal than you do steak—a little more than 12 times the greens to equal the calories in red meat.
But while the authors note that eating lettuce is “over three times worse in greenhouse gas emissions than eating bacon,” the takeaway is not that we should all be living off of pork belly to avoid catastrophic increases in global temperatures. “From an environmental standpoint, it is also important to consider both the source of our calories and the amount of calories we consume,” the authors continue. Not all lettuces are created alike, and a high-water fruit or vegetable grown in a desert, trucked across the country, and sold only in perfect condition is just not environmentally friendly. It’s a reminder that a healthy and sustainable diet isn’t just about the foods we eat but how they were grown and where they come from too.
“While our results are not intended to dissuade healthy eating, they do draw attention to the need for cooperative efforts between policymakers, health officials, and consumers,” the authors conclude.