Cardiovascular Disease

*This content has been reviewed by Dr. Donna Vine (Agriculture, Food and Nutritional Sciences, University of Alberta)

Cardiovascular disease (CVD) is an overarching term for a number of diseases affecting the circulatory system, including the heart, and the blood vessels in the lungs, brain, kidneys, or other parts of the body. These diseases include peripheral vascular disease, coronary heart disease, atherosclerotic CVD, and ischemic vascular disease. Ischemic cardiovascular disease is when a blood vessel becomes blocked and blood flow is compromised, resulting in an infarction, such as a myocardiocal infarction or heart attack, and a brain infarction or stroke. CVD and ischemic vascular events are a leading cause of morbidity and mortality death globally and in Canada (1, 2).

• Development of Cardiovascular Disease. The development of CVD depends on many risk factors, including those that are unmodifiable and those that are modifiable.
• Dietary and Lifestyle Recommendations. Consuming excess Calories from carbohydrates, fat, or other macronutrients, or consuming too much sodium may influence CVD risk factors.
• Sugars and Cardiovascular Disease. Current reviews of the evidence suggest it is the consumption of excess Calories, rather than sugar per se that influences CVD risk factors.
• Fructose and Cardiovascular Disease. Scientific studies that remove fructose from the diet, and replace fructose with other carbohydrates, find that there is no effect on CVD risk factors.

The Development of CVD Depends on Many Risk Factors

The development of CVD depends on some risk factors which cannot be controlled, while others may be modified to delay or prevent CVD development (see table below).

Maintaining a healthy body weight is encouraged as an important step in promoting cardiovascular health, as many factors leading to weight gain such as lack of exercise and an unhealthy dietary pattern can also contribute to CVD development.

Dietary and Lifestyle Recommendations to Maintain Cardiovascular Health

To maintain cardiovascular health, the Heart and Stroke Foundation (HSF) of Canada encourages Canadians to eat a healthy and balanced diet, control salt intake and be physically active (5). According to HSF, a healthy and balanced diet includes:

• Eating lots of vegetables and fruit
• Choosing whole grain foods more often
• Eating a variety of foods that provide protein
• Eating fewer highly processed foods that are high in added sugars, salt, and fats
• Reducing intake of sugars-sweetened beverages

The 2016 Canadian Cardiovascular Society Guidelines for the Management of Dyslipidemia for the Prevention of Cardiovascular Disease in the Adult suggest that combining multiple low-risk health behaviours is associated with benefit for the prevention of CVD (6). These include:

• Achieving and maintaining a healthy body weight,
• Healthy diet,
• Regular physical activity,
• Smoking cessation,
• Moderate alcohol consumption, and
• Sufficient sleep duration.

Sugars and Cardiovascular Disease

High quality evidence from randomized and non-randomized controlled trials offer the best available data to assess the relationship between dietary sugars intake and development of CVD. However, there are no clinical trials available that have assessed sugars intake with clinical outcomes of CVD, as these require long-term follow-up over many years and most nutrition trials last only a few weeks. Stand-in outcomes and CVD risk factors are therefore used to assess the association.

• Systematic review and meta-analysis found that for each additional serving per day of fruit and vegetables combined, there was a 4% reduction in CVD mortality (threshold at 5 servings a day) (7).
• Another systematic review and meta-analysis found that higher compared with lower intake of sugars was associated with modestly higher blood lipids (triglycerides, total cholesterol, LDL cholesterol, HDL cholesterol) (8). The increased or decreased body weight of participants in these studies is a factor, although the results are not consistent. Higher intake compared with lower intake of sugars was not associated with systolic blood pressure, but was associated with modestly higher diastolic blood pressure (8).
  • A limitation to some of these studies (as mentioned above) is that most are less than 8 weeks in duration, so longer term outcomes can’t be assessed.

Fructose and Cardiovascular Disease

Systematic reviews and meta-analyses of randomized controlled trials (9) examined all available literature, and concluded that:

• When fructose is substituted for other sources of carbohydrates, providing the same amount of total calories in the diet, there are no effect observed in any markers of CVD risk, specifically, there are not any significant changes to blood lipids (LDL-cholesterol, apolipoprotein B, non-HDL-cholesterol, HDL-cholesterol, and fasting or postprandial triglyceride levels).
• When fructose is added on top of a regular diet providing additional calories in the diet, there is an increase in some aspects of CVD risk, specifically, there are changes to blood lipids (apolipoprotein B, fasting and postprandial triglyceride levels). There were not any significant changes to other markers, including other blood lipids (fasting LDL-cholesterol, HDL-cholesterol, and non-HDL-cholesterol) or blood pressure (mean arterial pressure).

These results suggest that it is the consumption of excess Calories, not fructose specifically, that influences CVD risk factors (9).

A number of international health agencies have reviewed the scientific literature on sugars and CVD. For example, the Scientific Advisory Committee on Nutrition (SACN) in the United Kingdom states in their Carbohydrates and Health Report that there is no association between sugars and coronary events, systolic and diastolic blood pressure, fasting blood total cholesterol, LDL-cholesterol, HDL-cholesterol or triglyceride (10). However, the intake of sugars is positively associated with energy intake, which reflects sugars role in contributing to total dietary energy. As a result, sugars are not independently associated with cardiovascular events or risk factors beyond its caloric contribution.

References

1. The World Health Organization. 2017.  The top 10 causes of death.
2. Statistics Canada. 2015.  The 10 leading causes of death. 
3. Heart and Stroke. 2018.  Heart and Stroke Risk and Prevention. 
4. Government of Canada. 2009.  Minimizing the risks of Cardiovascular Disease. 
5. Heart and Stroke. 2018.  Healthy Eating.
6. Anderson TJ et al.  2016 Canadian Cardiovascular Society Guidelines for the Management of Dyslipidemia for the Prevention of Cardiovascular Disease in the Adult. Canadian Journal of Cardiology. 2016;32:1263-1282.
7. Wang X et al.  Fruit and vegetable consumption and mortality from all causes, cardiovascular disease, and cancer: systematic review and dose-response meta-analysis of prospective cohort studies. BMJ. 2014;349:g4490.
8. Te Morenga LA et al.  Dietary sugars and cardiometabolic risk: systematic review and meta-analyses of randomized controlled trials of the effects on blood pressure and lipids–. AJCN. 2014;100(1):65-79.
9. Khan TA and Sievenpiper JL.  Controversies about sugars: results from systematic reviews and meta-analyses on obesity, cardiometabolic disease and diabetes. Eur J Nutr. 2016;55:25-43. 
10. Public Health England Scientific Advisory Committee on Nutrition. 2015.  SACN Carbohydrates and Health Report.