Probing Question: Are local foods really best?

Melissa Beattie-Moss
June 27, 2012

A visit to the supermarket used to seem pretty straightforward. Need some fish or chicken? Buy some. Out of bananas? Toss a bunch in the cart. Running low on coffee? Grab a canister.

girl with watering can watering garden
Melissa Beattie-Moss

Tending garden

Sounds simple? Not so these days. Today’s health-conscious and eco-friendly shoppers are often armed with information (and a smartphone app or two) to decipher the complex politics of the plate. Beyond the choice to be an omnivore or vegetarian, many people are questioning whether the food they’re reaching for is cage-free or free range, wild-caught or farm-raised, organic, enriched, non-GMO, sustainable or Fair Trade.

Add one more question to the list: Is what you’re eating locally grown or raised?

The local food movement and the “locavores” who support it claim that eating food grown locally in season has many benefits, some that seem like common sense (fresher food tastes better) and some that are more debatable (eating local reduces GHGs, or greenhouse gas emissions.)

But how do you define “local” itself? It’s tough to find consensus, says Dorothy Blair, assistant professor of nutritional sciences at Penn State. “The U.S. Department of Agriculture points out that there really isn't an agreed-upon definition of local food,” she notes. “Locavores in Vermont defined it as a 100-mile radius from which they would access their food. But 100 miles is rather arbitrary, and actually this didn't work. They didn't even have the local oats needed to make granola.”

Explains Blair, the definition used to be based on a common watershed, and later on regions and supply chains. “I think the public tends to define ‘local’ as the farmer's markets and Community Supported Agriculture cooperatives (CSAs) in their county, but a county line is actually an arbitrary notion of local,” she adds. “A regional definition makes more sense, as it provides a longer harvesting season for crops such as broccoli, corn and strawberries.”

smiling woman

Dorothy Blair, assistant professor of nutritional sciences

There are some very good reasons to eat local when you can, notes Blair, including “enlarging the civic space and improving the economy, as dollars circulate locally rather than moving away.” But reducing “food miles”—the term used to describe how far food has traveled before you buy it—may be one of the movement’s weaker arguments.

“The term ‘food miles’ is somewhat misleading,” says Blair. “Unless you can walk or bike to your local food source, get it from your garden, or carpool, the extra mileage you put on your car to access local food negates the advantage.” Recent research indicates that, despite the fact that food typically travels 1,500 miles from farm to consumer in the U.S., fossil-fuel transportation is far from the greatest offender when it comes to the environmental price of our food system.

Studies show that agricultural production contributes 83 percent of the food system’s greenhouse gas emissions, before the food even leaves the farm, and suggests that “shifting less than one day per week’s worth of calories from red meat and dairy products to chicken, fish, eggs, or a vegetable-based diet achieves more GHG reduction than buying all locally sourced food.”
(Along these lines, the international campaign called Meatless Monday, launched by the Johns Hopkins’ Bloomberg School of Public Health, encourages people to not eat meat on Mondays to improve their health and the health of the planet.)

grocer at food stand holding sign that says Organic

Blair says organic farmers build their soil. Local farmers can also be organic, though many are not.

“Another big issue is the impact of chemicals used in conventional production,” says Blair. “I personally see organic food as a more important choice than local, because of the energy embedded in pesticides, nitrogen fertilizers, mined phosphorus (an endangered nutrient), and potassium. Organic techniques sequester carbon in soil. They don’t allow run-off of chemicals or loss of topsoil. Look what is happening in dead zones around New Orleans or to the Chesapeake Bay.”

Blair says organic farmers build their soil. Local farmers can also be organic, though many are not, she clarifies. “Also, many farmers do not declare themselves organic due to the costs of certification but are using these techniques. At least as a local buyer, one can ask. The buyer should be knowledgeable about what techniques make food environmentally sound and animal-friendly, and then talk to the farmer.”

Although it’s not the solution in and of itself, says Blair, “people who want to eat local
become politicized by the process of seeking alternatives to supermarket food,” and are taking steps “toward thinking more broadly about the effect of their consumption habits on the earth.”

The smartest way to eat local? “If you can, walking to your backyard garden to pick fresh vegetables is the best low energy food decision,” says Blair, “and good for your waistline as well!”

Dorothy A. Blair, Ph.D. is assistant professor of nutritional sciences and can be reached at

Last Updated June 27, 2012