Sugar warning: Scientists warn that even slight increases present cardiovascular disease risks

15 Feb 2023 --- Increasing daily consumption of free sugars by 5% of energy intake was found to increase the risk of total cardiovascular disease by 7%, the risk of ischemic heart disease (IHD) by 6% and the risk of strokes by 10%, according to a study published in BMC Medicine. Free sugars are sugars added to foods and drinks that naturally occur in honey, syrups and unsweetened fruit juice. 

“We hope that our findings will strengthen [global guidelines for free sugar intake] by providing evidence that this recommendation may also lower a person’s risk of developing cardiovascular disease,” Dr. Rebecca Kelly, lead author on the study, from the University of Oxford, tells NutritionInsight. 

Global guidelines recommend limiting free sugar to less than 5% of their daily energy intake. Still, Kelly says this is “largely based on limited evidence that this reduces the risk of tooth decay.” 

Zoe Davies, a nutritionist at Action on Sugar and Action on Salt, tells NutritionInsight that “this study is another piece of evidence that sugar reduction efforts must continue in the UK, and further reinforces the need for a focus on increasing population fiber intakes.” 

“We hope this study, alongside other research in this field, adds pressure on the government to implement policies to improve diets and prevent diseases such as cardiovascular disease.”

Limiting free sugar intake 
The researchers found that replacing refined grain starch and free sugars with whole grain starch and non-free sugars may help to protect against cardiovascular disease. 

“Consumers can reduce their intake of free sugars by consuming fewer desserts, sweets, sugary drinks and other foods with added sugars,” says Kelly. “Those with a sweet tooth can get non-free sugar from fruit, which is much healthier.” The study found that increased free sugar intake was associated with a higher risk of cardiovascular diseases. 

She adds that the primary dietary sources of free sugars observed were preserves, sweets, desserts, cakes and pastries. Fruit juice and sugar-sweetened beverages were also important sources of free sugars, accounting for 15.9% and 11.4% of free sugar intake, respectively. 

Food environment 
According to Davies, “Poor diets are a leading risk factor for many diseases, including cardiovascular disease, but many deaths can be prevented by improving what we eat.” 

She urges a change in the food environment, such as “addressing the nutrition content of food and drinks on supermarket shelves and ensuring the food industry reduces levels of free sugars, saturated fats, calories and salt.” Davies also calls for less marketing and advertising of unhealthy foods. 

The free sugar content of food and beverages is not always clear from packaging information. 

“Some food products suggest ‘no added sugar’ on the packaging but contain high levels of naturally occurring free sugar from fruit concentrates in their recipes,” Lisa Heggie, University College London, previously told NutritionInsight.

Further research 
Kelly explains, “an important next step is to explore the mechanism for the higher cardiovascular disease risks observed for high intakes of free sugars.” 

“It would be useful to examine the relationship of free sugars with other cardiovascular risk factors in detail, such as diabetes and overweight and obesity.”

Additional research could also overcome limitations in the current study, as the authors note that self-reported dietary assessment techniques are prone to error. The present study also could not account for dietary intake changes during the follow-up period.  

Studies with “more detailed dietary assessments may be able to examine the cardiovascular risks associated with different free sugar sources in detail,” according to Kelly. “For instance, free sugars from sugary drinks versus fruit juice.” 

The role of fibers 
According to the researchers, increasing fiber intake by 5 g a day was associated with a 4% lower risk of total cardiovascular disease. Common sources of free sugars include fruit juice, sugar-sweetened beverages, preserves, sweets, desserts, cakes and pastries.

However, this outcome was insignificant after adjusting for body mass index (BMI) and low-density lipoprotein (LDL) cholesterol. The researchers explain that participants with the highest fiber intake also had a lower average BMI and LDL cholesterol levels. 

Davies adds that consumers need to eat more fiber. “There are many beneficial effects associated with fiber and the government recommends that we eat 30 g a day. This would lower the risk of heart disease, stroke, Type 2 diabetes and bowel cancer.” 

NutritionInsight reported earlier on a study by Tate & Lyle that adding fiber to everyday foods could lower the risk of heart disease for 72% of the UK population. 

Setup of the study  
The researchers analyzed data from 110,497 individuals from the UK Biobank who were free from cardiovascular disease and diabetes at the start of the research period. The study tracked participants for 9.4 years. 

Participants of the study completed at least two 24-hour dietary assessments through an online questionnaire at the start of the study period. 

The researchers calculated carbohydrate intakes by multiplying the carbohydrate content of food and beverages with the frequency of consumption, using food composition tables from the UK Nutrient Databank. Next, they separated carbohydrates into free and non-free sugars. 

The study measured cases of cardiovascular diseases with hospital admissions. Out of the 110,497 participants, the researchers recorded 4,188 incidents of total cardiovascular diseases, 3,138 incidents of IHD and 1,124 strokes. 

By Jolanda van Hal 

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