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KAI RYSSDAL: There was news this morning Burger King's making some menu changes. The burger chain said it's going to start getting its eggs from free-range hens. And pork from free-range pigs. Trouble is, there isn't really enough free-range stuff to go 'round. Burger King says it'll start small and ramp up. So we asked Marketplace's Alisa Roth to look into whether it can really make a difference.

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ALISA ROTH: Every year, the Burger King stores in North America go through around 35 million pounds of pork. And more than 40 million pounds of eggs. The company says it's going to try to get those eggs from free-range chickens. And pork from pigs that aren't kept in cages.

Marcia Mogelonsky is an analyst at research firm Mintel International. She says the company's responding to popular requests.

MARCIA MOGELONSKY: There is a growing sensibility among the general population that we should be trying to eat in a more ethical fashion.

Like other fast food restaurants, Burger King has also been hammered by animal rights activists for ignoring animal welfare. But Mogelonsky warns the definition of free-range is still pretty loose, so it's hard to know exactly what Burger King's planning to do.

In any case, the company says it can't get nearly enough free-range products to meet its needs. So for now, only about 2 percent of the eggs and 10 percent of the pork products will be free-range. The hamburger chain says it'll use more as the stuff becomes available.

Sherry Day Scott edits QSR magazine, a trade publication for the food industry. She says demand from the fast-food business could change that.

SHERRY DAY SCOTT: If McDonald's and Burger King tomorrow said in 10 years we're only going to be serving organic beef, you would see not only just the small mom and pops, but the Tysons, everyone, change over to that.

Still, she says, most Americans don't care where their chicken comes from. They just want to know they won't get salmonella or worse from that $1.50 burger special.

In New York, I'm Alisa Roth for Marketplace.