If most of your food doesn’t come with microwaveable directions, you may have noticed a trend called the local food movement. Yes, it’s everywhere.

It hasn’t hurt that books like The Omnivore’s Dilemma by Michael Pollan or Barbara Kingsolver’s Animal, Vegetable, Miracle have reached millions of readers as they tout the healthy, albeit difficult, struggle to take time to taste the heirloom, organic, homegrown tomato.

But if you’re anything like me, the hubbub hasn’t simplified the search for a nutritious, delicious meal with a low environmental impact. It only complicated things. I realized this a couple of months ago after standing paralyzed in front of a bin of Honeycrisp apples at the Park Slope farmers market in Brooklyn, New York. The apples had been picked just hours earlier, yet weren’t organic. And so I hesitated filling my bag, wondering if it’s better to buy conventionally grown local apples or organic apples trucked in from thousands of miles away.

In a 2001 study by the Leopold Center for Sustainable Agriculture, researchers found that locally grown produce in Iowa traveled an average of 65 miles before reaching the market, while conventional produce traveled an average of 1,494 miles, nearly 27 times further. If food miles, or the distance a person’s food travels from production to market, signify sustainability, local food would be the hands-down better choice for the planet.

But are they? Not necessarily, says Richard Pirog, associate director at the Leopold Center. “Food miles turn out to be a great indicator of localness, but were never intended to be a proxy for environmental impact,” Pirog says. The reason being it sometimes takes more energy to grow and harvest local food than it does to grow it far away and have it shipped in.

It turns out that more greenhouse gas emissions are released from producing a juicy steak (or any red meat for that matter) than any other form of food. Red meat is responsible for about 150 percent more emissions than chicken or fish. That’s according to research done by Christopher L. Weber and H. Scott Matthews of Carnegie Mellon University, who argued in a 2007 study (Food-Miles and the Climate Impacts of Freight Transportation in American Food Consumption) that if you’re trying to limit your food’s carbon footprint, it is better to eat lower on the food chain than to eat local.

In this vein, the food pyramid becomes more than just a healthy diet guide; it’s a carbon calculator, with foods at the bottom of the pyramid — whole grains, fruits and vegetables — having the lowest carbon footprint, and those at the top — dairy, meat and sweets — the highest.

But has sustainability really been distilled in terms of a product’s carbon footprint? If the recent carbon footprint eco-labels from Tesco, Wal-Mart and Tropicana serve as an indicator, the answer would be yes. Yet people like Jonathan Kaplan, a senior policy specialist at the Natural Resources Defense Council, say not so fast. Sustainability is a broad concept with many complicated facets — carbon footprint being just one of them.

Others aspects include farm management techniques (such as soil tilling, pesticide and fertilizer use, handling of waste products), how the products are shipped and how much water is used. That’s why the Natural Resources Defense Council, along with 230 other scientists, farmers and businesses, are trying to create the “Stewardship Index,” a system for measuring sustainable performance across the supply chain: at farms, processors, distributors, food service providers and retailers.

It would be used by large food processors to find environmental weaknesses in the supply chain. Take Unilever, one of the largest food processors, as an example. The company asked its California tomato farmers to measure the amount of fertilizer they use on their fields. What Unilever discovered is that some farmers were using twice as much fertilizer than other farmers, but growing the same amount of tomatoes.

This information could then be used to improve fertilizer efficiency, which in turn reduces fertilizer runoff in streams and carbon emissions in the atmosphere.

For individuals and families, however, Kaplan suggests four principles to eating sustainably and listed them in order of importance: eating lower on the food chain, reducing food waste, supporting eco labels and other sustainable certifications, and eating locally whenever possible.

After months of feeling guilty about walking away from the conventionally grown apples that day in Brooklyn, I felt at ease. In the end, each person has to decide make his or her own decisions about food. Next time, I think I’ll seek out fruit that’s local and organic, even if it means relinquishing my mouthwatering desire for an apple. Hey, I’m not one to turn down local, organic blueberries.

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