In a letter to U.S. Health Secretary Kathleen Sebelius, the American Cancer Society's advocacy affiliate on Tuesday called for a comprehensive review along the lines of the U.S. top doctor's landmark report on the dangers of smoking in 1964.

"An unbiased and comprehensive report on the impact of sugar-sweetened beverages could have a major impact on the public's consciousness and perhaps begin to change the direction of public behavior in their choices of food and drinks," American Cancer Society Cancer Action Network wrote.

"There seems to be a consensus about the problem and the cause, but what is lacking is an articulate, science-based and comprehensive national plan of action," it added.

The role of sugar-sweetened drinks such as soft drinks -sometimes called soda - sports drinks, teas and juices in the U.S. diet has drawn fresh attention in the wake of a New York City plan announced in May that would limit the cup sizes for such beverages to 16 ounces (0.47 liter).

Its proposal has reverberated elsewhere across the United States, where two-thirds of people are overweight or obese and health costs are spiraling. Other cities and towns are also looking at ways to curb consumption, citing the need to improve the public health and save money.

The beverage industry, which includes The Coca-Cola Co, PepsiCo Inc and Dr Pepper Snapple Group Inc, has defended its products even as it has moved to sell other options that consumers see as healthier. Some of those drinks, however, also contain as much sugar and calories as soda.

"We already have studies from the federal government and independent third parties that demonstrate soft drinks are not a unique or significant contributor to obesity," Karen Hanretty, a spokeswoman for the American Beverage Association, said in response to the letter.

SYMBOLIC ROLE

The U.S. Surgeon General's office plays a largely symbolic role but is often looked to for direction on significant health issues. Department of Health and Human Services spokeswoman Tara Broido gave no comment except to say that the agency had not yet received the letter.

Health experts and advocates say that while food and lack of exercise contribute to obesity, data show sugary drinks are a large part of the problem. The Institute of Medicine, the health arm of the National Academy of Sciences, in May called for more policies to reduce overconsumption of sugary drinks.

Dick Woodruff, vice President of federal affairs for the cancer society's advocacy arm, said the group was not trying to demonize the beverage industry but rather seek an unbiased review of all available science.

"There is an obesity epidemic ... and one in three cancer deaths are due to nutrition and physical activities, including overweight and obesity," he told Reuters.

Another advocacy group has also cited a more direct link between sodas and cancer.

The Center for Science in the Public Interest (CSPI), a U.S. watchdog group, is seeking a ban on the use of chemically enhanced caramel coloring in soft drinks in favor of pure caramel from sugar. High levels of the chemical, called 4-methylimidazole or 4-MI, have been linked to cancer in animals.

Coca-Cola and PepsiCo have said they would reduce the chemical to avoid cancer warning labels on products sold in California, even though the Food and Drug Administration has said the drinks are safe. Last week, CSPI said Coca-Cola's namesake soft drink still contains a high level of the chemical in several countries.

(Editing by Eric Walsh)

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