The letter to Philippe Dauman, president of Viacom Inc., and Cyma Zarghami, president of Nickelodeon, was coordinated by the coalition Food Marketing Workgroup, led by the non-profit Center for Science in the Public Interest in Washington and Berkeley Media Studies Group.
The coalition included the American Cancer Society, American Heart Association, Jamie Oliver Food Foundation, Environmental Working Group and others.
"We appreciate Nickelodeon's efforts to promote healthy lifestyles to children," the letter said.
"However, such efforts are insufficient given the magnitude of the problem. Your public service announcements, philanthropic activities and partnerships with children's groups do not counterbalance the effect of Nickelodeon's core business and children's exposure to food marketing. The mix of Nickelodeon's marketing remains out of balance, doing more to promote unhealthy than healthy eating."
The coalition said Nickelodeon took some small steps, including a policy to limit the licensing of Nick characters to healthier food products. However, SpongeBob SquarePants and Dora the Explorer are still being used to promote unhealthy foods such as imitation fruit snacks, Popsicles, PEZ candy, Cheese Nips crackers and Kraft Macaroni & Cheese, the Food Marketing Workgroup said.