A study released Monday offers even more evidence of the harmful health effects of sugar.
The research, published in the journal BMC Medicine, found that diets higher in free sugars — a category that includes sugar added to processed foods and sodas, as well as that found in fruit juice and syrups — raise one's risk of heart disease and stroke.
The study relied on data about the eating habits of more than 110,000 people ages 37 to 73 in the United Kingdom, whose health outcomes were then tracked over about nine years.
The results suggested that each 5% increase in the share of a person's total energy intake that comes from free sugars was associated with a 6% higher risk of heart disease and a 10% higher risk of stroke.
An author of the study, Cody Watling, a doctoral student at the University of Oxford, said the most common forms of sugar the study participants ate were "preserves and confectionary," with the latter category including cookies, sugary pastries and scones. Fruit juice, sugar-sweetened beverages and desserts were also common, he added.
Sugars that occur naturally in whole fruits and vegetables are not considered "free sugars" and were excluded from the analysis.
Watling and his team relied on data from the UK Biobank, a large-scale database of health records, which included multiple assessments of participants' diets. The researchers analyzed the assessments to estimate participants' carbohydrate intakes, then further broke that down by type of carbohydrate to focus on free sugars.
Then the authors compared that to the participants' incidence of cardiovascular disease.
The people found to have the highest risk of heart disease or stroke consumed about 95 grams of free sugar per day, or 18% of their daily energy intake, Watling said.
By comparison, U.S. guidelines suggest that added sugars should make up no more than 10% of one's daily calories.
"Avoiding sugar-sweetened beverages is probably the single most important thing we can be doing," said Walter Willett, a professor of epidemiology and nutrition at Harvard University who was not involved in the study.
Willett added that although there are some health benefits to drinking a small glass of orange juice occasionally, its sugar content means "a glass of fruit juice is the same thing as Coke."
Watling said guidelines about sugar intake rely on percentages of total energy because setting a limit in grams does not consider the variations in people’s dietary needs.
"Say, for example, you take someone who identifies as female and they’re small — their energy requirements for their body are a lot less than someone that’s 6 [foot] 7, a man that’s very tall. They’re going to have to consume more food," Watling said.
The Oxford researchers found a positive relationship when it comes to fiber, unlike sugar intake: Consuming 5 grams of fiber a day was associated with a 4% lower risk of heart disease, the study suggested, although that did not hold true when researchers controlled for participants' body-mass indexes.
A large body of previous research has also found health benefits associated with fiber consumption, as well as risks linked to diets high in sugar. The authors of the new study said their research builds on the existing evidence by including sugars in honey, syrups and fruit juice in the analysis, rather than looking solely at added sugars.
They noted, however, that the association they found between free sugars and stroke risk warrants further research.
Still, Watling said, the study demonstrates that the types of carbs people choose to eat may matter more than the total amount.
"What's really important for overall general health and well-being is that we're consuming carbohydrates that are rich in whole grains," he said, while "minimizing the consumption of sugar-sweetened beverages, as well any kind of confectionary products that have added sugars."