David Barbano, director of the Northeast Dairy Foods Research Center, operated by Cornell and the University of Vermont and supported by the dairy industry, grew up drinking raw milk on a family farm. He does not remember ever getting sick, but says science has never found any evidence that it was more beneficial than pasteurized milk. In fact, he said, raw milk has very little vitamin D, which is added to most pasteurized milk.

“There is always going to be a percentage of raw milk that carries disease-causing bacteria,” said Dr. Barbano, who is a professor of food science at Cornell. “As long as I have pasteurized milk available for me, and I guess more importantly for my daughter, the risk is not worth any benefit anyone has been able to prove.”

Sally Fallon, president of the Westin A. Price Foundation, another nutrition advocacy group, argues that the risk to raw milk drinkers is insignificant, and the demand for product is growing steadily. In 1998, when the Washington-based foundation created the Web site realmilk.com, it barely had half a page of sources where raw milk could be purchased legally. Now, the list has grown to more than two dozen pages, and Ms. Fallon puts the number of raw milk drinkers at half a million.

“We are trying to be pragmatic and create demand,” said Ms. Fallon of the 10,000-member, 400-chapter foundation, which has mounted legal challenges to raw milk regulations in several states. “Even though it is illegal in some places, it is very available through cow sharing or cow herding programs.”

In Virginia, for example, Chip and Susan Planck — Nina’s parents — pay $40 a year plus $25 monthly to own a share in one cow, the only legal way to get raw milk in that state. In return, they get a gallon of raw milk a week. It is technically not a sale but compensation for the cow’s room and board.

Last year the Hawthorne Valley Farm in Ghent, N.Y., offered a buyers’ club program to its raw milk customers in the hopes of giving a bigger boost to a steadily growing market. It was designed to encourage those customers in New York and beyond to order in bulk but send only one representative a week to pick up the order.

When the New York State Department Public Interestand Markets caught wind of it, however, it asked Hawthorne to end the program and the farm complied. Still, Abe Madey, the farm’s dairy manager and cheesemaker, says business is steady. About 100 regular customers, many of whom drive two hours from New York City, purchase up to 7,500 gallons annually of raw milk worth about $45,000 to the farm, he said.