Eating too much ‘free sugar’ has 45 negative health effects, study finds

(CNN) — There are at least 45 good reasons to cut back on added sugar, according to a new study.

Copious research has shown the negative effects of excessive sugar intake on health, which has informed recommendations to limit consumption of "free" or added sugar to less than 10% of a person’s daily caloric intake.

Still, researchers in China and the United States felt that before developing detailed policies for sugar restriction, the "quality of existing evidence needs to be comprehensively evaluated," according to the study published Wednesday in the journal The BMJ.

In a large review of 73 meta-analyses — which included 8,601 studies — high consumption of added sugar was associated with significantly higher risks of 45 negative health outcomes, including diabetes, gout, obesity, high blood pressure, heart attack, stroke, cancer, asthma, tooth decay, depression and early death.

Free sugars — the type of sugar the authors focused on — are those added during the processing of foods; packaged as table sugar and other sweeteners; and naturally occurring in syrups, honey, fruit juice, vegetable juice, purees, pastes and similar products in which the cellular structure of the food has been broken down, according to the US Food and Drug Administration. This category does not include sugars naturally occurring in dairy or structurally whole fruits and vegetables.

The study "provides a useful overview of the current state of the science on sugar consumption and our health … and confirms that eating too much sugar is likely to cause problems," said Dr. Maya Adam, director of Health Media Innovation and clinical assistant professor of pediatrics at Stanford University School of Medicine. Adam wasn’t involved in the study.

"Studies like this are helpful in advising patients that seemingly small changes, such as cutting out excess sugar like sugar-sweetened beverages, can have a marked and positive improvement to health," said CNN Medical Analyst Dr. Leana Wen, an emergency physician and public health professor at George Washington University, who wasn’t involved in the study.

Moderate-quality evidence suggested that participants with the highest consumption of sugar-sweetened beverages had higher body weight than those with the lowest intake.

"As a nutrition researcher who served on both the 2010 and 2020 US Dietary Guidelines Advisory Committees, I can confirm that intake of dietary sugar in the US is more than twice the recommended amount (less than 10% of total daily caloric intake) and while the direct impact of sugar itself offers minimal, if any, nutritional benefits, it further replaces foods that do," said Linda Van Horn, professor emeritus of preventive medicine at Northwestern University’s Feinberg School of Medicine, via email. Van Horn wasn’t involved in the study.

The connection between sugar and disease

Evidence of a link between free sugar and cancer has been limited and controversial, and needs more research, the study’s authors said. But the finding, according to the study, could be explained by the known effects of sugar on weight: High sugar consumption has been associated with obesity, which is a strong risk factor for various cancers. The same goes for cardiovascular disease.

"Added sugar intake can promote inflammation in the body, and this can cause stress on the heart and blood vessels, which can lead to increased blood pressure," behavioral scientist Brooke Aggarwal told CNN in February. Aggarwal, an assistant professor of medical sciences in the cardiology division at Columbia University Irving Medical Center, wasn’t involved in the study.

Highly processed foods, which can have lots of free sugar, have been found to increase inflammation, a risk factor for depression.

"Whole food carbohydrates take longer to break down into simple sugars, and a part of them — the fiber — can’t be broken down at all," Adam told CNN in February. "This means that whole, intact grains don’t cause the same spikes in blood sugar that we experience when we eat simple sugars. Blood sugar spikes trigger insulin spikes, which can destabilize our blood glucose and … be the underlying cause of health problems in the long run."

Reducing your intake

The findings — in combination with existing guidance from the World Health Organization, World Cancer Research Fund and American Institute for Cancer Research — suggest people should limit free sugar intake to less than 25 grams, or about 6 teaspoons, per day. There’s that much sugar in 2 ½ chocolate chip cookies, 16 ounces of fruit punch and about 1 ½ tablespoons of honey. A doughnut has around 15 to 30 grams of sugar, according to the Cleveland Clinic.

The authors also recommend reducing consumption of sugar-sweetened beverages to less than one serving (about 200 to 355 milliliters) per week. That’s the equivalent of an up to 12-ounce soda, Aggarwal said via email.

To change sugar consumption patterns, the authors think "a combination of widespread public health education and policies worldwide is urgently needed."

But there are some changes you can begin making on your own.

Be aware of what you’re putting in your body by reading nutrition labels when shopping — even the ones on foods you might not think of as sweet, such as bread, breakfast cereals, yogurts or condiments. These foods usually have lots of added sugar, and it adds up, Adam said.

Opt for water sweetened with fruit slices instead of sugary drinks and have fresh or frozen fruit for dessert instead of cakes, cookies or ice cream. Cooking and baking at home more often is one of the best ways to reduce sugar intake, Aggarwal said.

Getting enough good-quality sleep on a regular basis would also help "as we tend to choose foods higher in sugar when we’re tired," Aggarwal said. Cutting back gradually can help you train your taste buds to crave less sugar.

"Our lives will probably end up being sweeter with less sugar in our diets," Adam said.

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