Walking away from the grocery store cashier, many of us often feel a little stunned by what we just spent. How do really poor people handle the cost? Since eating is our most essential human need — as revolutions begin and end with empty bellies — the price of food is a pressing political, not to mention humane, issue.

Locavorism is a food philosophy that encourages people to eat only or mostly locally produced food. Advocates tend to argue that it is a more nutritious way to eat, primarily because most small, local farmers raise their foods organically. Local food, then, is less likely to be contaminated by pesticides and chemicals. Additionally, local food can ripen "on the vine" before being picked, so more nutrients and enzymes have developed within the food; produce loses not only freshness but also nutritional value the sooner it is picked and the more it sits. On the meat side of things, the more humanely and naturally livestock is raised, the greater the chance its flesh will be healthy for consumers.

Local Money

Another tack taken by local food proponents is that it is important to help the local economy by spending within your own community. Not only will you be financially supporting your neighbors, but you will also be saving money as farmer's markets are often less expensive than grocery stores. Local food uses less fuel to get from the farm to your refrigerator, cutting down on pollution. If these arguments don't grab you, advocates of the local food movement often end with a simple taste claim: the flavor of ripe, local food is generally superior to food products that have been packaged and then shipped a great distance.

Among the local food movement's many advocates is author and professor Michael Pollan, who wrote in an open letter to President Obama published in The New York Times, "the food and agriculture policies you've inherited - designed to maximize production at all costs and relying on cheap energy to do so - are in shambles, and the need to address the problems they have caused is acute." He amplifies the normally acoustic locavore arguments. "After cars, the food system uses more fossil fuel than any other sector of the economy - 19 percent," Pollan wrote. He also argues that our food practices contribute more greenhouse gases to the atmosphere "than anything else we do." He speaks, too, of chronic diseases being linked to diet, in particular, heart disease, stroke, type 2 diabetes, and cancer, and suggests that local food is healthier for you. He even raises the specter of national security: "...we have little control over the safety of imported foods. The deliberate contamination of our food presents another national-security threat."

Who can argue with that?

Global Food

Well, Pierre Desrochers, an associate professor of geography at the University of Toronto, and Hiroko Shimizu, who holds a master's of international public policy from Osaka University, can. Both have been research fellows of the Property and Environment Research Center in Bozeman, Mont., and the Institute for Policy Studies at Johns Hopkins University. Instead of relying on fear-based reasoning, as Pollan does, they argue history. "What enthusiastic locavores fail to understand is that their "innovative" ideas are up against regional advantages for certain types of food production, economies of scale of various kinds in all lines of work, and the absolute necessity of large urban agglomerations reliant on long distance trade for economic development," they wrote in an article published in The American. "These basic realities defeated very sophisticated local food production systems in the past."

In support of going beyond one's own 'foodshed,' they discuss, like Pollan, both the economy and energy. "Cost-efficient long-distance transportation made it possible to channel the surplus of regions that had experienced good harvests to those that had not, in the process ending famine in developed economies," Desrochers and Shimizu wrote. They believe producing food requires more energy than transporting it, so the most environmentally-friendly food policy exists when agriculture consumes the least amount of land globally. Only agri-business can deliver this efficiency, they believe, adding that locavores fail to take into account the mode of transit by which food and specifically produce often travel.

Desrochers and Shimizu also argue that producing and shipping from regions best suited to certain crops consume less energy than producing those crops elsewhere. "The locavores' vision fails to acknowledge that the good old days were more akin to trying times and that long distance trade in all kinds of goods and services remains essential for human progress," the authors concluded. "The sooner they redirect their efforts toward real agricultural problems---from costly production subsidies to international trade barriers---the better humanity and the planet will be."

As much as agricultural policy may dismay (or interest) you, feeding your family in as healthy a manner as possible weighs more heavily on you. Yet recent research only complicates this question even more.

Down to You

A recent study conducted by researchers at UC Davis compared frozen, canned, and fresh food. The study finds that frozen and canned food may offer equal nutritional value when compared with produce that has been sitting for days in a grocery aisle. "Losses of nutrients during fresh storage may be more substantial than consumers realize," wrote the authors. "Depending on the commodity, freezing and canning processes may preserve nutrient value. While the initial thermal treatment of canned products can result in loss, nutrients are relatively stable during subsequent storage owing to the lack of oxygen. Frozen products lose fewer nutrients initially because of the short heating time in blanching, but they lose more nutrients during storage owing to oxidation. In addition to quality degradation, fresh fruits and vegetables usually lose nutrients more rapidly than canned or frozen products. Other variables such as storage and cooking conditions will also influence the final nutrient content of a food."

In other words, it's complicated. Inevitably, though, this debate about local food comes down to you and if you want to stay healthy and desire the cleanest, most nutritious food you can afford. Maybe it's time to turn down the mental noise and let your senses choose for you. Seeing, smelling, and tasting fresh food is enough to convince most of us.

Source: Rickman JC, Barrett DM, Bruhn CM. Review Nutritional comparison of fresh, frozen and canned fruits and vegetables. Part 1. Vitamins C and B and phenolic compounds. Journal of the Science of Food and Agriculture. 2007.