The Crucial Role of Nutrition in the Fight Against Cardiovascular Disease

How prevalent is CVD globally?

Cardiovascular disease (CVD) remains one of the biggest threats to human health and is a significant concern for medical and scientific communities globally. Currently, CVDs such as coronary heart disease (CHD) and stroke represent 31% of all global deaths, with an estimated 17.5 million people dying each year from the disease¹. It is the leading cause of death among both men and women in the US^2, and it is estimated that one in five adults in China has CVD, with the country having one of the highest CVD death rates in the world³. 

What are the main risk factors for developing CVD? 

Risk factors fall into two categories: those that cannot be prevented, such as age, and those that can be prevented. Of the latter, a surprising number can be attributed to lifestyle; these include smoking, high blood pressure, elevated blood lipids, sedentary lifestyles, obesity and, importantly, poor nutrition. Lowering one’s body mass index (BMI) to within the ‘normal’ range of 20 – 25kg/m2 can help to reduce blood pressure, blood lipids and the occurrence of a sedentary lifestyle. This can be achieved by maintaining caloric intake, if BMI already falls within this range, or via a negative balance of calories if BMI is greater than 25kg/m2, complemented by an increase in exercise to burn calories. 

Although many risk factors are related to lifestyle, a change in lifestyle may not always be easy, possible or achieved rapidly. In such cases, drugs, such as statins, are needed to treat elevated blood lipids, and other drugs can be used to treat high blood pressure or even an addiction to smoking.

The composition of one’s diet is also an important factor in the occurrence of CVD. The Western diet, increasingly popular across the globe, is rich in sodium, sugar-sweetened beverages and deficient in marine based omega-3 fatty acids (EPA; DHA), vitamin D, nuts/seeds and wholegrains. As a result, individuals living on this diet are at greater risk of heart attack, stroke, type 2 diabetes and even death⁴, with dietary factors estimated to be associated with a substantial proportion of mortalities⁵. Alternatively, the Mediterranean diet, rich in nuts, oily fish, fruits and vegetables, with limited intake of red meat, sodium and sugar-sweetened beverages, has been found to reduce the occurrence of cardiovascular events⁶. 

There is also a strong correlation between certain biomarkers, such as diabetes, and CVD; in fact, the American Heart Association has reported that adults with diabetes are up to four times more likely to die from heart disease than those without diabetes⁷.

What are the current guidelines for reducing the risk of CVD via contributory lifestyle factors?

Guidelines vary from region to region, but globally it is agreed that patients at elevated risk of CVD should follow a cardio-protective diet featuring fruits, vegetables, wholegrains, lean meats, poultry, fish, nuts, legumes and seeds, with a limited intake of added sugars⁸.  The difficulty lies in the reliance on patients making changes to significantly improve their own lifestyles, as individuals are not necessarily following current advice. This is, in part, due to gaps in patient - and even physician - knowledge as to what constitutes a well-balanced, nutritious diet, and how to achieve it. Recently, biomarkers have been used to measure an individual’s supply of important ingredients. The most advanced biomarkers are for vitamin D and omega-3 fatty acids (EPA; DHA), and a large proportion of the populations tested have been found to be deficient in these two components^9,10. Guidelines continue to evolve as more evidence comes to light¹¹.

What role can nutrition play in supporting cardiovascular health?  

Just as poor nutrition can play a key role in increasing the risk of CVD, a well-balanced, nutrient-rich diet can help to prevent or dramatically reduce the risk of developing CVD. The World Health Organization (WHO) states that adequate changes in lifestyle can prevent three quarters of all CVD mortality, and there is growing evidence for the influences of different foods and nutrients, and their role in the prevention of CVD ^12-15. There is also extensive research indicating that key nutrients, including omega-3 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), as well as vitamin D, can support heart health¹⁶.

What is the evidence linking omega-3 EPA and DHA to a reduction in risk factors associated with developing CVD? 

There is growing evidence to suggest that omega-3 EPA and DHA can help to reduce the risk of developing CVD. In fact, in 2012, the European Commission authorized an Article 13.1 health claim that 250mg per day of EPA and DHA contributes to normal heart function¹⁷. In 2013, additional Article 13.1 claims were authorised for “DHA and EPA contribute to the maintenance of normal blood pressure” (for a daily intake of 3g of EPA and DHA) and “DHA and EPA contribute to the maintenance of normal blood triglyceride levels” (for a daily intake of 2 g of EPA and DHA.¹⁸

In addition to this, a new meta-analysis of studies assessing the relationship of EPA and DHA on CHD found that the risk of CHD in individuals with elevated triglycerides or LDL cholesterol was significantly reduced with EPA and DHA supplementation¹⁹. However, a substantial number of large intervention trials with supplements of EPA and DHA in cardiovascular disease did not have positive results, or reported neutral results. Therefore, the European Society of Cardiology (ESC) does currently not endorse the use of EPA and DHA supplements in the guidelines for Cardiovascular Prevention.²⁰ It is not likely that ineffectiveness of EPA and DHA can be linked to the restricted positive or neutral outcome of these trials. It is rather a question of bioavailability of EPA and DHA and issues related to the trial methodology, which were recently revealed by measuring levels of EPA and DHA using the standardized HS-Omega-3 Index®. ²¹. Currently, many say that a new generation of level-based large intervention trials are needed to gain a more accurate representation and understanding of the impact of EPA and DHA on cardiovascular health.

Nevertheless, based on positive results obtained from a number of trials and the totality of the evidence, the American Heart Association (AHA) recently issued a statement strongly supporting the use of EPA and DHA supplements in congestive heart failure and, less strongly, in patients who have had a recent heart attack.²².

What is the evidence linking vitamin D to a reduction in mortality due to CVD?

Traditionally recognized for its importance in maintaining bone health, higher levels of vitamin D have also been found to be associated with longevity and a reduction in the occurrence of cardiovascular events.

Vitamin D levels are measured as 25(OH) vitamin D in serum, and risk for both mortality and cardiovascular events increases at levels lower than 30 ng/ml, equivalent to 75 nmol/l²³. Vitamin D also plays a beneficial role in the regulation of high blood pressure²⁴ and a reduction in the risk of hypertension and CHD²⁵. Although a meta-analysis of intervention trials has found that increasing intake of vitamin D reduces total mortality, cardiac societies currently do not support the use of vitamin D as a supplement, although intake of up to 100µg per day is considered safe by EFSA²⁶. Optimal levels of vitamin D can be achieved safely in adults by the daily intake of vitamin D3 of up to 100 mg or 4000 I.E. per day²⁷.

What about other key nutrients?

Key nutrients, including vitamins C and E, and soluble fibers such as oat beta-glucan, have been also found to play a role in supporting heart health. 

Vitamin E has been linked to a lowered risk of developing a cardiovascular condition due to oxidative stress and inflammation, as well as helping to protect cells from damage and maintaining arterial health^28,29,30. Meanwhile, vitamin C can support heart health – higher levels of the vitamin have been linked to lower blood pressure³¹, as well as improved vasodilation in individuals with CHD ³².

Research on soluble fibers has also highlighted the cholesterol lowering potential of oat beta-glucan and a subsequent reduction in the risk of developing heart disease³³. A claim on reduction of a disease risk factor has been authorised in the EU in 2011 for oat beta-glucan for a daily intake of 3 g: “Oat beta-glucan has been shown to lower/reduce blood cholesterol. High cholesterol is a risk factor in the development of coronary heart disease”³⁴

How could the overall approach to supporting cardiovascular health be improved?

The global shift to an increased consumption of nutrient-poor foods is likely an important factor behind the rising levels of CVD worldwide, but support from governments, regulatory bodies and healthcare practitioners can help the food industry to reverse this trend and ensure that a nutritious, well-balanced diet is accessible and affordable to all. 

It is also crucial that efforts are made across the globe to increase public awareness and understanding of the importance of good nutrition to encourage the adoption of lifestyle and dietary habits that will support cardiovascular health. Reviewing current guidelines could help to achieve this, and providing a consistent approach in the recommendation of cardiovascular health strategies could lead to an increase in the intake of essential micronutrients to help improve cardiovascular health worldwide.