Sugary drinks raise cardiovascular disease risk, but occasional sweets don't

In the lead-up to the festive season, and all the parties and gatherings that come with it, we’re likely to be indulging in more sugary desserts and sweetened drinks that we know aren’t all that good for us. But although most public health bodies recommend limiting sugar consumption to protect your teeth and improve your diet, there has previously been limited evidence regarding the impact of sugar intake on cardiovascular diseases.

To understand how sugar consumption affects cardiovascular disease risk, and whether consuming different kinds of sugar changes those risks, scientists from Lund University and the University of Copenhagen collected data from two major cohort studies: the Swedish Mammography Cohort and the Cohort of Swedish Men. These studies had diet questionnaires administered in 1997 and 2009, allowing the scientists to monitor participants’ diets over time.

Once exclusions had been made to ensure the two cohorts shared the same inclusion criteria and to remove independent risk factors for cardiovascular diseases, the scientists were left with a sample of 69,705 participants. They looked at three classes of sugar consumption — toppings like honey, treats like a pastry, or sweetened beverages like fizzy drinks — and seven cardiovascular diseases.

The participants were monitored until they died, were diagnosed with one of the cardiovascular diseases, or reached the end of the follow-up period in 2019. During this period, 25,739 participants were diagnosed with a cardiovascular disease. The scientists then used this data to break down how the different types of sugar intake affect the risk of different cardiovascular diseases.

The researchers found that although higher sugar intake raises your risk of certain cardiovascular diseases, consuming sweet drinks is worse for your health than any other form of sugar, increasing the risk of ischemic stroke, heart failure, atrial fibrillation and abdominal aortic aneurysm. Their results have been published in Frontiers in Public Health.

“Liquid sugars, found in sweetened beverages, typically provide less satiety than solid forms — they make you feel less full — potentially leading to overconsumption,” said Suzanne Janzi, PhD candidate at Lund University and corresponding author of the study. “Context also matters — treats are often enjoyed in social settings or special occasions, while sweetened beverages might be consumed more regularly.”

Different cardiovascular diseases were affected differently by increased sugar intake, possibly because consuming additional sugar affected participants’ individual risk profile differently. Increased sugar in general raised the risk of ischemic stroke and abdominal aortic aneurysm, as well as increasing the risk of heart failure in participants with a normal BMI. Extremely low sugar consumption was also associated with poorer cardiovascular health, with the lowest risks of cardiovascular diseases found among people who ate occasional treats.

“This might reflect underlying dietary behaviours — individuals consuming very little sugar might have very restrictive diets or might be limiting sugar due to pre-existing health conditions,” Janzi suggested. “While our observational study cannot establish causation, these findings suggest that extremely low sugar intake may not be necessary or beneficial for cardiovascular health.”

The scientists noted that more work will be needed to understand the mechanisms involved in the differential effects of different types of sugar consumption. They also pointed out that diet is highly demographically and culturally specific, with the dietary habits of the Swedish population potentially differing from those in other populations.

“Particularly relevant in this context is the social custom of ‘fika’ — regular coffee and pastry breaks that are deeply embedded in Swedish culture,” Janzi said. These results may not directly translate to other populations with different dietary cultures.”

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