A new study published in the Annals of Internal Medicine questions whether the current recommended limits on added sugars—set by many health organizations—are actually valid.

Researchers from University of Minnesota, McMaster University, and The Hospital for Sick Children Research Institute concluded that the current guidelines “do not meet criteria for trustworthy recommendations and are based on low-quality evidence.”

“We are very uncertain about the effects of sugar on long-term health outcomes of importance to the public,” says Bradley Johnston, Ph.D., principal investigator of the study and a professor at McMaster University and the University of Toronto.

The authors reviewed public health guidelines on “added sugars” from nine organizations from around the world—including the U.S. Department of Agriculture and the World Health Organization. Added sugars are those that a food manufacturer adds to a food, for example—not the types of sugars naturally present in fruit, milk, and some vegetables.

Some of the guidelines they looked at— including the WHO’s Guidelines For Sugars Intake in Adults and Children—advise people to keep their added sugar intake below a specific amount, ranging from 5 to 25 percent of daily calories.  

But other researchers argue that this new study's conclusions are flawed. There also is concern that the study may be biased because the authors have ties to the food and beverage industry. 

Examining the Evidence

A growing body of research has linked a diet high in added sugars to obesity, heart disease, type 2 diabetes, and other health problems. Says Maxine Siegel, R.D., a dietitian and head of the Consumer Reports food testing lab: “Sugary drinks, candy, and desserts are huge contributors, but added sugars are also found in less obvious places, such as in frozen meals, cereal, yogurt, sauces, and salad dressings.”

In this new study, the researchers chose to examine whether the current recommended guidelines for sugars intake were valid by looking at the studies and the methodology used to set the guidelines. Their finding: The evidence doesn’t support coming up with hard-and-fast cutoffs, such as getting 10 percent or fewer calories from added sugars every day.

But in an editorial accompanying the study, Dean Schillinger, M.D., chief of the division of general internal medicine at San Francisco General Hospital argues that the assessment tools the study authors applied were not used appropriately. “They were selective methods that virtually guaranteed that they would find the results they did,” he says.  

Ties to Industry

Another concern is that the study authors have ties to the food and beverage industries. Funding for the study came from the International Life Sciences Institute, a nonprofit science organization whose members include companies such as Coca-Cola, General Mills, and Hershey. And one of the study’s authors is on the scientific advisory board of Tate & Lyle, a larger supplier of high fructose corn syrup.

The authors disclosed their funding source and said that their analysis was carried out independently. But “there is a well-documented practice of manipulation when the sugar-sweetened beverage and junk food industry is involved in science,” Schillinger said. “So we were compelled to look at this study very carefully to determine if the conclusions are valid.”


Do You Need to Cut Back—or Not?

Bottom line, though: Even the authors of the new study aren’t saying you can eat as much added sugars as you want.

“Our findings should not be used to justify high or increased consumption of sugary foods and beverages,” says Johnston.

While other experts acknowledge there isn’t a “smoking gun” study yet that demonstrates with complete certainty that eating too much added sugars causes disease in people, they say the research is solid enough to urge restraint in consuming added sugars.