"The American Heart Association is concerned that the ban of trans fat in restaurants in its current form may not be the best course of proposed action," the AHA said in written testimony obtained by the New York Post.
Trans fats have been shown in a host of recent studies to raise "bad" LDL cholesterol levels and contribute to heart disease and other health disorders.
A broad range of medical groups -- including the American College of Cardiology, the American Cancer Society, the American Diabetes Association, the American Medical Association, the American Society of Hypertension, the Medical Society of New York and the New York Academy of Medicine -- have come out in support of Mayor Bloomberg's ban, which would require most New York restaurants to eliminate trans fats from their menus by next July.
However, the AHA claims the ban doesn't allow restaurants enough time to seek out healthy alternatives, which could force them to use high-saturated-fat oils such as palm or coconut oil.
"We are concerned that there is the potential for unintended and adverse consequences, such as restaurants returning to the use of oils high in saturated or animal-based far if healthier oils are in short supply," said AHA representative Megan Lozito. "These unhealthy substitutes also pose important health risks."
New York City Health Commissioner Thomas Frieden said plenty of healthier, alternative oils would be available.
Consumer health advocate Mike Adams, author of "Poison In the Food: Hydrogenated Oils," said the AHA is defending a substance that has been proven to harm human health.
"It is almost unimaginable that an organization claiming to support heart health would not be entirely in favor of an outright ban on a substance that has been scientifically established as a danger to human health," Adams said.
"It really makes you wonder whether the AHA has the best interests of the public in mind, or if it is favoring the interests of food corporations that pay the AHA money to license its logo," he said.
The AHA said it favors working with restaurants to gradually eliminate trans fats from foods, as well as allowing them more time to find suitable alternatives, rather than enforcing a quick ban.