While pondering the many choices I have to make when buying tomatoes—How important is it to buy local? Is it worth it to buy organic? Should I even considered canned?—I started to wonder whether the interests of my body and the environment coincide. Is eating healthy better for the environment, too?
You raise a critical point. Too often, environmentalists slip half-knowingly between human health and environmental health. Ask a stranger in the grocery store why he buys organic, and he’ll almost certainly conflate the two issues. We’re all one, after all. Gaia or whatever.
Unfortunately, there’s no natural law saying that planet health and human health are unitary. Consider the potato. According to a 20-year study involving more than 120,000 people, potatoes correlate more closely with obesity than any other food (including soda). And yet, potatoes aren’t exactly giving Mother Earth diabetes, so to speak.
It takes 466 kilocalories of energy to produce a pound of potatoes, according to research by David Pimentel of Cornell University. That’s an unremarkable cost for produce. Spinach—a certified superfood packed with phytochemicals—requires 1,139 kilocalories per pound. Other health foods like Brussels sprouts and snap beans also take significantly more fossil fuel energy to produce than the maligned potato. A heaping bowl of steamed greens might be good for you, but the planet would prefer that you ate a plateful of microwaved potatoes.
The situation becomes even more complicated when you think about fresh, frozen, and canned foods. Michelle Obama has made fresh food a centerpiece of her campaign for health (even though not everyone agrees that fresher is healthier). And yet, there are many circumstances in which limp, salty, canned food is better for the environment.
Environmental research firm Scientific Certification Systems compared the embedded energy in fresh, frozen, and canned foods in a 2005 study. They found that it takes 1,136 kilocalories of energy to produce 1 pound of canned, prepared foods like soups and stews. Fresh foods came in at 1,151 kilocalories of energy per pound, a statistical dead heat with the canned meals. Canned, unprepared foods, like green beans and corn, were scored at 1,606 kilocalories per pound, and frozen foods rated between 2,250 and 2,405 kilocalories, depending on packaging.
Before you committed environmentalists go on a potato-and-soup diet, a few caveats are in order. First, although the study was conducted by a respected company and subjected to peer review, it was funded by the canning industry. Second, the research is based on a specific set of assumptions that might not apply to you.
Start with transportation. Canned foods are energy-intensive on the front end—between 40 and 50 percent of their embedded energy comes from heating the ingredients and sticking them into a can. Because canned food is cooked down and efficiently packed, however, you can fit more of it on a truck. Only 7 percent of the embedded energy in canned food goes toward transport, according to the study, compared with between 21 and 27 percent for fresh foods.
The SCS analysts assumed that all foods traveled about 1,500 miles by truck from farm to table. That’s reasonable, because a lot of food goes from California to the East Coast. But if you cut back on food miles by buying local, then canned foods wouldn't look quite so good. If you assumed a 300-mile trip instead of a 1,500-mile one, fresh food would be significantly more efficient than canned prepared meals overall, rather than slightly less so. (Frozen food would still be way behind. Frozen food is bad for the environment. Sorry, Green Giant.)
Same goes for storage. Keeping fresh green beans refrigerated at the store and in your home accounts for 18 percent of their embedded energy, compared with zero storage kilocalories for their shelf-stable canned counterparts. Go to the farmers’ market for your green beans—excuse me, haricots vert—and eat them the same day, and that difference disappears.
This discussion wouldn’t be complete without a mention of farming methods. Organic farming generates a lot of intense debate. Despite a few studies suggesting that conventional agriculture might be more energy efficient for certain foods, the Lantern believes that organic really is better for the environment. In a decades-long study of staple crops grown on adjacent fields by the Rodale Institute, organic methods required 30 percent less energy to produce corn and drew about even on soybeans. By the end of the experiment, the nutrients in the organic soil had substantially increased, while the conventional fields had stayed the same or had been depleted. Conventional fields also lack organic matter to prevent water from running off. That means leaching of pesticides into groundwater, as well as soil erosion. You should take soil erosion seriously. The stuff in which we grow our food is disappearing between 10 and 40 times faster than it’s being renewed, and we’re losing 37,000 square miles of crop land every year to the problem.
Of course, the jury is still out on whether organic food is any healthier than conventionally grown products. That’s just one more place where planet health and human health might not match up.