Added Sugars and Cardiovascular Disease – Is There a New Cause for Concern?
A recent newsletter post
from McGill University reviewed a U.K. study (1) that concluded that consuming higher amounts of added sugars increased cardiovascular disease (CVD) risk. The World Health Organization (WHO) defines free sugars as monosaccharides and disaccharides that are added to foods and drinks (by manufacturers, cooks or consumers) and includes sugars that are naturally found in honey, syrups, fruit juices and fruit juice concentrates (2).
This is an important topic with CVDs (including coronary heart disease (CHD), cerebrovascular disease and peripheral vascular disease) being the leading cause of death globally (in 2019 this represented 32% of all global deaths) (3). The PEN Team decided to explore if a change in practice guidance is needed based on this study.
Study analysis - strengths and weaknesses
The prospective cohort U.K. “Biobank Study” recruited 110,000 people, aged 37 to 73 years, who self-completed two to five 24-hour dietary questionnaires between 2006 and 2010 (1). Information on lifestyle and sociodemographic factors was collected at baseline along with physical measurements and biological samples.
All subjects were free of CVD and diabetes at the beginning of the study (1). The types of carbohydrates analyzed were total sugars (free sugars, non-free sugars (total sugars minus free sugars) and fibre (non-starch polysaccharides)) and sources of carbohydrates (refined grain starch and whole grain starch). At the start of the study, lifestyle and sociodemographic factors were collected via participant questionnaire and interview, and physical measurements and biological samples were collected using standardized procedures.
There were 8500 participants who developed CVD by the end of the study period (1). The authors found that every 5% of energy from free sugars was associated with increased risk of total CVD (HR 95%CI 1.07, 1.03 to 1.10), CHD (1.06, 1.02 to 1.10) and stroke (1.10, 1.04 to 1.17). In contrast, every 5 g/day of dietary fibre was associated with decreased risk of total CVD (HR 95%CI 0.96, 0.93 to 0.99), and substituting 5% of energy from refined grain starch with whole grain starch reduced the risk of CVD and CHD. In addition, a higher intake of free sugars was found to be linked with higher concentrations of triglycerides.
Study strengths include:
- long term (10 years)
- large sample size
- prospective study design
- detailed dietary data on different carbohydrate types and sources; however, major sources of free sugars were not able to be identified.
Study weaknesses include:
- single study
- lack of generalizability beyond participants who were predominantly white European descent and well educated
- self-reported 24-hour recalls
- unable to account for changes in dietary intakes during the study follow-up period
- lack of control for confounders that may be associated with CVD risk (e.g. family history of CVD, diabetes, smoking, physical activity)
- causality cannot be inferred in this observational study.
This study helps to further support the idea that quality rather than quantity of carbohydrates promotes CVD health.
- Based on a PEN 2018 practice question, Are diets lower in free sugars (including sugar-sweetened beverages) recommended for the primary prevention of cardiovascular disease (CVD) or secondary prevention of CVD (i.e. individuals with a history of CVD or with multiple CVD risk factors, e.g. metabolic syndrome)?, the PEN Team continues to suggest limiting the intake of free sugars (including sugar-sweetened beverages) for primary and secondary CVD prevention. This is a conditional recommendation as it is based on low quality evidence.
- Based on another PEN practice question, Are diets higher in total dietary fibre (including whole grains, cereals, vegetables, fruit and legume/pulse fibre) recommended for primary or secondary cardiovascular disease (CVD) prevention?, the PEN Team suggests high intakes of total dietary fibre (at least 25-29 g/day) (conditional recommendation, moderate quality evidence) and replacing refined grains with whole grains (conditional recommendation, low quality evidence) for primary and secondary CVD prevention.
Country-specific guidelines include:
The WHO recommends no more than 10% of total energy intake per day from added sugars (ideally, less than 5%) (2). This is about 50 grams (or 12 teaspoons) per day.
The Australian and New Zealand Dietary Guidelines follow the WHO guidelines and recommend limiting the intake of foods and drinks containing added sugars such as confectionery, sugar-sweetened soft drinks and cordials, fruit drinks, vitamin waters, energy and sports drinks (4).
The Heart and Stroke Foundation of Canada recommends no more than 10% of total energy intake per day from added sugars (ideally, less than 5%) (5). This is about 48 grams (or 12 teaspoons) per day.
The Scientific Advisory Committee on Nutrition (SACN) recommends that free sugars account for no more than 5% of total daily energy (calories) intake (6). This is about 19 g (or 5 sugar cubes) for children aged four to six, 24 g (6 sugar cubes) for children aged seven to ten, and 30 g (7 sugar cubes) for 11 years and over.
The PEN Team will continue to review the literature. Content will be updated when new high quality studies are available that assess the effects of low intake of free sugars on CVD outcomes in both healthy adults and in those at high CVD risk or with preexisting CVD.
- Kelly RK, Tong TYN, Watling CZ, Reynolds A, Piernas C, Schmidt JA, et al. Associations between types and sources of dietary carbohydrates and cardiovascular disease risk: a prospective cohort study of UK Biobank participants. BMC Med. 2023 Feb 14;21(1):34. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/36782209/
- World Health Organization. Guideline: sugars intake for adults and children. 2015. Available from: http://www.who.int/nutrition/publications/guidelines/sugars_intake/en/
- World Health Organization. Cardiovascular diseases (CVDs). 2021 Jun. Available from: https://www.who.int/news-room/fact-sheets/detail/cardiovascular-diseases-(cvds)
- Food Standards Australia and New Zealand. Sugar. 2019 Aug. Available from: https://www.foodstandards.gov.au/consumer/nutrition/Pages/Sugar.aspx#:~:text=For%20an%20adult%20of%20a,Bureau%20of%20Satistics%20website%E2%80%8B
- Health and Stroke Foundation of Canada. Reduce sugar. 2022 Jun. Available from: https://www.canada.ca/en/health-canada/services/nutrients/sugars.html
- Government UK. SACN carbohydrates and health report. 2015 Jul. Available from: https://www.gov.uk/government/publications/sacn-carbohydrates-and-health-report