Citing "confidentiality" issues, CPS did not allow the Tribune to visit lunchrooms to interview students about what they drink at lunch. But Jessica Hawkins, a senior who like Beckwith contributes to The Mash, a Chicago Tribune Media Group publication for high schoolers, said she and her friends often feel pressured to take milk with their meals.
Lunch workers say, "You need a milk with that," Hawkins said.
Mikhaela Padilla, a Whitney Young High School junior, said: Students "take it because they feel bad and that's what they've been taught to do."
What happens then? A waste audit conducted at one Chicago elementary school concluded that the equivalent of about 200 cartons of milk (many of them unopened) were thrown away at lunch during a single typical day.
Earlier this year, CPS supplied the Tribune with a waste audit from five schools participating in the district's "breakfast in the classroom" program. The results suggest that up to half of the milk given out was thrown in the garbage.
The CPS milk contract with C&M JV1 Co., boosted by last year's launch of the mandatory breakfast program, now exceeds $20 million a year. Some of that is covered by the federal government, but district officials said they couldn't be specific because the costs are factored into the full meal reimbursement.
The district pays the company an average of 23 cents per carton, or about $92,000 a day for 400,000 half-pints, much of it funded by taxpayers whose money goes down the drain with any discarded milk.
It's unclear what role lactose intolerance plays when students choose not to drink milk with lunch. Milk consumption by American children and adolescents has dropped sharply, according to an analysis by the Dairy Research Institute of data from the Centers for Disease Control and Prevention.
The most recent figures, from 2007-10, indicate that only about 57 percent of U.S. teenagers drink milk, down from 75 percent three decades ago. For children 6 to 12 years old, the percentage fell to 73 percent from 90 percent.
Erin Quann, director of regulatory affairs for the National Dairy Council, said there could be many reasons kids throw away their school milk.
"Is it served cold? Do they have enough time? And do they have access to other fluids within the school day that they see as an alternative?" she said.
The dairy council is hoping to reverse the decline in milk consumption. "Kids need more milk, not less," Quann said. "They are already not getting the calcium they need to avoid compromising bone health in the future."
Other nutritionists say the benefits of milk to children are being overstated.
In 2005, the journal Pediatrics published an analysis by Lanou, of UNC-Asheville, finding that "scant evidence supports ... increasing milk intake ... for child and adolescent bone" health. Lanou notes that national bone health has not deteriorated measurably despite decreases in milk consumption.
This year, researchers at Boston Children's Hospital reported in the Archives of Pediatric and Adolescent Medicine that they had found no relationship between dairy or calcium consumption and the incidence of stress fractures among 6,712 preadolescent and adolescent girls.
The study did, however, find a benefit from vitamin D consumption. Linda Van Horn, who served on the federal Dietary Guidelines Advisory Committee, said that link is one of the reasons the panel recommended three daily servings of dairy.
"Milk fortification with vitamin D represents the single greatest source of dietary vitamin D that exists in our food supply," said Van Horn, a professor of medicine at Northwestern University. The Dairy Council also notes that milk provides magnesium, potassium and protein.
The Physicians Committee for Responsible Medicine, a group that promotes a plant-based diet, cited the Boston study in filing a petition in July asking that the USDA eliminate dairy requirements from the school lunch program. The group has also asked CPS and other districts to make milk substitutes available to all students.
Susan Levin, the group's nutrition director, said she questions the USDA's ability to dispense impartial nutrition advice when it also has a mission to market American agricultural goods, including milk.
"It would be wonderful if the USDA made all the regulations in the National School Lunch Program line up with science," Levin said. "But unfortunately they have another mandate to support agricultural sales, and those two things don't always lead to the healthiest possible lunches."
The USDA declined to comment but said the petition was under review.
Dr. Frank Greer, a physician and former nutrition chairman for the American Academy of Pediatrics, notes that African-Americans "show the biggest, strongest bones of all groups" despite their low rate of milk consumption. Conversely, Caucasians have some of the highest dairy calcium consumption and poorest bone health.
While diet plays a role, "the most important determinant of bone health is genetics," said Greer, a University of Wisconsin at Madison medical professor.
Greer and Van Horn agree that although milk offers a nutrient package that is hard to replace with other foods, alternatives should be offered to lactose-intolerant students. Greg Miller, executive vice president of research and regulatory and scientific affairs for the National Dairy Council, concurs.
"For lactose maldigesters, there are alternatives like lactose-free milk and yogurt, which is also very well tolerated," said Miller, adding that some can tolerate small amounts of milk with food. "There are many, many options."
All acknowledge that alternatives would cost more than regular milk. But, said Levin, "this is an investment in kids' health at school, and you have to be patient and understand that it will pay off in ways that are not just financial."