The biggest overhaul of US food labels in more than two decades is likely to help improve the diets of the most health-conscious but others may need more convincing.
Public health advocates have welcomed the new rules but say some of those most at risk for obesity and diet-related illness may not change habits without other measures to discourage sugar consumption, such as taxes on sugar and food advertising warning labels.
The US Food and Drug Administration on Friday (Saturday AEST) announced new Nutrition Facts packaged food label rules that include disclosure of how much sugar is added to thousands of processed foods ranging from soda to spaghetti sauce.
Curbing excess sugar consumption is key to whittling waist lines in the United States, where more than one-third of adults are obese, and to reducing the prevalence of heart disease, stroke, type 2 diabetes and certain types of cancer.
Roughly two thirds of adults already are trying to cut back on their sugar intake, said Darren Seifer, a food and beverage industry analyst for The NPD Group, a New York-based market research company.
"This might actually have an effect. Sugar is the focal point for consumers right now," Seifer said.
Food industry groups, many of which had fought the new rules, said they would comply with the changes. That included the Grocery Manufacturers Association, an industry group whose members include food and beverage companies, which said that consumers could be confused by the changes and would need education.
A review of research from several countries, published in the journal Public Health Nutrition in 2011, found a consistent link between the use of nutrition labels and healthier diets, but wide differentiation in how groups responded to labels.
"It's a useful tool for those who are really educated and concerned, and has zero effect on the population most at need," said Barry Popkin, a professor of nutrition at the University of North Carolina at Chapel Hill.
Popkin and Kelly Brownell, dean of the Sanford School of Public Policy at Duke University, said labels would be more effective when combined with other measures.
Chile has banned the use of toys to market food to children, for instance, and Mexico, the UK and some US jurisdictions tax soda. A new San Francisco law requires health warning labels on public advertisements for sugary beverages.
"I don't think anyone expects that the labels themselves will be sufficient. Lots of other interventions will be necessary," Brownell said.
Experts noted that big behavioural changes could come if the new rules prompted food makers to rework their recipes. After the FDA began requiring trans fat information on nutrition labels in 2006, many food makers responded by cutting artificial trans fats.
