Of course, we all know we should limit sugar. It's a treat to be enjoyed sometimes, not in excess. The question is, how much is too much and how much is just right to protect our health?
These questions are not so easily answered. Advice about how much sugar to include in your diet is offered by many public health organizations, but a new report, just published in the Annals of Internal Medicine, finds that the guidelines on sugar limits vary greatly and that many are not based on rock-solid evidence.1
What else you might need to know before your next treat:
Researchers reviewed nine guidelines from prestigious organizations and sources, including the World Health Organization and the U.S. Dietary Guidelines for Americans. Some say to limit sugar intake to less than five percent of your total calories, others suggest less than 25 percent is OK.
If it's difficult to visualize how much sugar either of those recommendations might allow, figure that if you eat, say, 10% of total calories from sugar and have a typical 2,000 calorie a day diet, you should cap it at 50 grams or 12 teaspoons. Sobering perspective: a single chocolate candy bar can have 8 teaspoons or more.2
Why the disagreement and variation? Researchers who conducted the study say that the creators of the different guidelines looked at different evidence and they had different ways of evaluating how much sugar should be limited.
"You can ask the questions in different ways," says Joanne Slavin, PhD, RD, a study coauthor and professor of food science and nutrition at the University of Minnesota, St. Paul. One research team may look at how much sugar is linked to a specific health outcome, such as heart problems or diabetes or dental decay. Another may look at sugar habits and see what happened to people in terms of other outcomes, such as longevity.
Researchers evaluated the evidence in the different studies using different methods, as well.
When the study was published, some experts took strong exception, noting that the conclusions were biased due to industry sponsorship. The study was funded by the International Life Sciences Institute (ILSI), an industry non-profit member group. Its members include scientists as well as food companies, pharmaceutical firms, biotech companies and agricultural companies.
The study authors noted that the protocol was written by them and that the study was conducted independently from ILSI.
Despite that reassurance, an editorial that accompanied the study was harshly critical. "When it comes to added sugars, there are clear conflicts between public health interests and the interests of the food and beverage (F&B) industry," wrote the two editorialists, both from the University of California San Francisco. "Studies are more likely to conclude there is no relationship between sugar consumption and health outcomes when investigators receive financial support from F&B companies."3
Neither the study authors nor the critics are saying not to worry about sugar intake. The study authors are calling for standardization of basic terms and for setting guidelines. Even the definition of carbohydrates is up for grabs, says Dr. Slavin. "In Europe they talk about free sugars, and that would include the sugars in fruit juice," she says. However, in the U.S., fruit juice sugars are not considered added sugar. Settling on a common definition would help researchers, she says.
While researchers aim to standardize both research and guidelines, experts do agree that excess sugar is linked with a host of ailments, from cardiovascular problems to obesity risk, poor blood sugar control and dental cavities.
The crucial message is to know that added sugars are low in nutritional value and that they have a limited place in your diet. "They provide flavor and calories," says Connie Diekman, RD, MEd, director university nutrition at Washington University in St. Louis. She commented on the new study. She never tells people to eliminate sugar—but to fit it into a healthful eating plan.
So yes, you can enjoy a cookie or a candy bar or a piece of cake sometimes, she says. She says blaming a single food for weight woes is not going to help anyone. Having a sugary treat now and then is OK, she says. However, she also advises that people trying to reduce their sugar intake not replace the sugar with worse options. A prime example, she says, is cutting out dessert but adding salty snacks.