Green carts are taking hold in New York City's food deserts, according to a new study by Columbia University's School of International and Public Affairs. The study, released Wednesday, said the city's 6-year-old program to bring fresh produce to low-income neighborhoods is working well for the most part.

The study said the city's 166 green carts are located in neighborhoods with few places to buy quality fruits and vegetables, and where people have high rates of diet-related diseases. More than half of their customers are regulars who report eating more produce since shopping at the carts.

"It really is penetrating this population," said Ester Fuchs, a professor of international and public affairs and political science at Columbia SIPA who led the green cart study. "People are using it who have high needs and they are purchasing fresh fruits and vegetables from these vendors."

The study also said vendors are benefiting from the green cart program through decent profits. And, three-quarters of the city's green cart vendors reported they believe the job will help them eventually open a larger business.

But it could be better: the study found that the city needs a better tracking system for green carts to prevent vendors from clustering in some areas, leaving others without a piece of fruit in sight. The study also called for more green carts near public housing.

Surveyors in the study reported that 68 percent of the produce at green carts was good quality. But in a recent report on WNYC, people in the Bronx, where many green carts are located, indicated there's no guarantee that they are eating or cooking that produce after they buy it.

The study was supported by the Laurie M. Tisch Illumination Fund, the same foundation that partnered with the city to create the green carts program.