expert opinion

Micronutrients and cardiovascular disease prevention in Europe

February 1, 2012

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The European Heart Network (EHN), based in Brussels, is an alliance of heart foundations and non-governmental organizations from all over Europe.

“Dietary and lifestyle changes can help prevent cardiovascular disease (primary prevention), but they can also help prevent the progression of the disease in people who already have symptoms or have been identified as being at high risk (secondary prevention). Given the complex, multi-factorial nature of cardiovascular disease (CVD), it is not possible to identify all those at risk, nor are the risks confined to people in high-risk groups. In fact, the total burden of cardiovascular disease from those with a moderate level of risk factors is greater than the total burden from those at higher risk (1). The potential to save lives and prevent ill-health is much greater if prevention efforts are directed at the wider population rather than only at those who show clinical signs of illness or risk factors. While dietary and lifestyle changes are tremendously important for individuals with cardiovascular conditions or those who have been identified as being at high risk, it is vital that prevention efforts also focus on the general population without any CVD symptoms.

Saturated fatty acids (SAFA) increase plasma total- and LDL - cholesterol, both of which are strongly related to the risk of coronary heart disease (2). Replacing saturated fat by polyunsaturated fatty acids (PUFA) is the simplest way of reducing serum cholesterol on a population scale in Western societies (3, 4). Prospective studies also show that replacing saturated fat by PUFA lowers the risk of coronary heart disease (CHD)-related mortality (5). Intake of very long-chain omega-3 fatty acids (VLCn-3 PUFA) was associated with a decreased risk of CHD mortality and events. A review discussed somewhat contradictory study results: an increase in the risk of CHD death was seen at the highest category of dietary PUFA, while a 5% increase in PUFA intake was associated with a significant reduction in CHD events (6). The authors discuss the short-comings of this kind of study, such as measurement errors, regression dilution bias, confounding, etc. Based upon the findings of several recent reviews, there is convincing evidence that VLCn-3 PUFA intake – in the form of fish or eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplements – reduces the risk of CHD death and sudden cardiac death and possibly CHD events in patients with heart disease (6-10). A pooled analysis of both prospective cohort studies and randomized clinical studies for individuals with pre-existing CHD demonstrated that an intake of 250 mg/d achieved a reduction of CHD death that peaked at 36% (9). In terms of fish consumption, one to two servings of (oily) fish per week, i.e., approximately 250 to 500 mg/d, was associated with nearly the maximum risk reduction possible (11). In conclusion, there is convincing evidence that VLCn-3 PUFA intake reduces the risk of CHD. The current state of knowledge supports the recommended minimum VLCn-3 PUFA intake of 250 mg/d as a population goal for the prevention of CHD. This is equivalent to two portions of fish per week.

Evidence from systematic reviews and meta-analyses show that eating more fruit and vegetables will decrease the risk of cardiovascular disease, especially in regard to coronary heart disease and stroke. The benefit of fruit and vegetable consumption has been found to be linear (the more consumed, the greater the risk reduction), with no determined upper limit as yet. The exact risk reduction varies between papers; the way it is presented also varies. However, there seems to be a 17-21% reduction of CHD risk if an individual eats five portions of fruits or vegetables per day (12, 13). Similarly this quantity of fruits and vegetables is also reflected in a 25-26% reduction in the risk of stroke (14). At present, it is not clear what the underlying mechanisms behind these findings are; whether it is the antioxidant properties (e.g., vitamin C decreasing LDL oxidation and atherosclerosis risk), the high potassium content (which decreases blood pressure), or folate (which decreases plasma homocysteine concentrations). Nor is it clear whether all fruits or vegetables or only specific sorts confer such benefits. More information needs to be gathered on the mechanisms of action and perhaps also on the benefits of individual fruits or vegetables. However, it is not necessary to wait to discover the underlying mechanism before recommending a diet rich in fruits and vegetables to help reduce the burden of cardiovascular disease.

There have been some significant changes in the nutritional quality of the diets, mainly in Southern Europe. Two aspects are of concern: First, the possible changes in the quality of high-value foods, such as fruits, vegetables, lean meats, and fish, i.e., changes in the types of fruits and vegetables and the nutrient profiles of meat or fish. Second, the larger changes in the patterns of food eaten, namely, the loss of the traditional Mediterranean diet. Its relatively high levels of fruit, vegetables, olive oil, and fish are being replaced with soft drinks, candy, snack foods, and fast food meals. One analysis of the fruits and vegetables purchased in Spanish households over the course of recent decades showed that changing patterns – such as a decline in green leafy vegetables and green beans – might alter the nutritional qualities of the total diet (15). The analysis indicates a significant decline in the average daily intake of carotenoids, such as beta-carotene, lycopene, lutein and zeaxanthin, between 1990 and 2004. It was assumed that carotenoid levels in each type of fruit and vegetable remained steady, although there is some evidence that modern growing and processing methods (e.g., growing under glass, ripening after harvesting) may reduce these micronutrient levels compared to more traditional methods.”

Based on: European Heart Network. Diet, physical activity and cardiovascular disease prevention in Europe. November 2011.

References

  1. World Health Organization. 2008-2013 Action Plan for the Global Strategy for the Prevention and Control of Noncommunicable Diseases. Geneva: WHO, 2009.
  2. Graham I. et al. European guidelines on cardiovascular disease prevention in clinical practice: executive summary. Eur Heart J. 2007; 28:2375–2414.
  3. Clarke R. et al. Dietary lipids and blood cholesterol: quantitative meta-analysis of metabolic ward studies. BMJ. 1997; 314:112–117.
  4. Mensink R. P. et al. Effects of dietary fatty acids and carbohydrates on the ratio of serum total to HDL cholesterol and on serum lipids and apolipoproteins: a metaanalysis of 60 controlled trials. Am J Clin Nutr. 2003; 77:1146–1155.
  5. Jacobsen M. U. et al. Major types of dietary fat and risk of coronary heart disease: a pooled analysis of 11 cohort studies. Am J Clin Nutr. 2009; 89:1425–1432.
  6. Skeaff C. M. and Miller J. Dietary fat and coronary heart disease: Summary of evidence from prospective cohort and randomised controlled trials. Ann Nutr Metab. 2009; 55:173–201.
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  8. Harris W. S. et al. Tissue n-3 and n-6 fatty acids and risk for coronary heart disease events. Atherosclerosis. 2007; 193:1–10.
  9. Mozaffarian D. Fish and n-3 fatty acids for prevention of fatal coronary heart disease and sudden cardiac death. Am J Clin Nutr. 2008; 87:1991S–19916S.
  10. Pedersen J. I. et al. Adipose tissue fatty acids and risk of myocardial infarction - a case-control study. Eur J Clin Nutr. 2000; 54:618–625.
  11. Mozaffarian D. and Rimm E. B. Fish intake, contaminants, and human health: evaluating the risks and benefits. JAMA. 2006; 296:1885–1899.
  12. Mente A. et al. A systematic review of the evidence supporting a causal link between dietary factors and coronary heart disease. Arch Intern Med. 2009; 3:659–669.
  13. He F. J. et al. Increased consumption of fruit and vegetables is related to a reduced risk of coronary heart disease: meta-analysis of cohort studies. J Hum Hypertens. 2007; 21(9):717–728.
  14. He F. J. et al. Fruit and vegetable consumption and stroke: meta-analysis of cohort studies. Lancet. 2006; 367(9507):320–326.
  15. Granado F. et al. Changes in carotenoid intake from fruit and vegetables in the Spanish population over the period 1964-2004. Public Health Nutrition. 2007; 10(10):1018–1023.