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Protecting against cardiovascular disease

Luci Daniels
BSc Nutr RD
Fellow BDA
Practising Dietitian

Cardiovascular disease (CVD), including coronary heart disease (CHD) and stroke, is one of the most common causes of morbidity and mortality in the UK. In 2002 it accounted for just under 238,000 deaths, or 39% of all deaths, with around half of these being attributed to CHD and a quarter to stroke. Premature deaths in those under the age of 75 years are of particular concern.
The comprehensive British Heart Foundation CVD statistics for 2002 list the number of premature deaths from CVD at 67,000 - 35% of the total for men and 27% of the total for women.
Increased spending on the treatment of CVD has caused a year-on-year reduction in the mortality rates, with 3,000 fewer CHD deaths in 2003. There are significant regional variations in the UK, with higher rates in Scotland and the north of England and lower rates in the south.(1)
The National Service Framework for CHD sets out the standards and challenges to the NHS for delivering improved healthcare.(2) Nutrition and diet has an important part to play in both the prevention and treatment of CHD and stroke.
It is now increasingly recognised that dietary modification is an important part of any primary or secondary CVD prevention programme. The 1994 COMA report, Nutritional Aspects of Cardiovascular Disease, makes diet and lifestyle recommendations that form the basis of many of today's CVD prevention advice.(3)

Risk factors for cardiovascular disease
CVD is multifactorial with risk factors traditionally
differentiated into modifiable and nonmodifiable.
Modifiable risk factors include:

  • Smoking.
  • Dyslipidaemia.
  • Hypertension.
  • Obesity.
  • Waist circumference >102cm for men and >88cm for women.
  • Poor diet.
  • Lack of physical activity.
  • Hyperglycaemia and type 2 diabetes.
  • Hyperinsulinaemia.
  • Increased clotting tendency.
  • Raised homocysteine levels.

Apart from smoking, all of these risk factors can be related to diet.
Nonmodifiable risk factors include:

  • Age.
  • Gender.
  • Genetics.
  • Disease states, including type 1 diabetes, stroke and renal disease.

Assessing the risk
The British Hypertension Society and others have updated their risk assessment tables showing the 10-year risk of developing CVD in "healthy individuals", taking into account age, smoking, blood pressure and total cholesterol:HDL-cholesterol ratio.(4) The revised tables advise that people with diabetes should be considered as if they have established CVD.

Target high-risk individuals
Priority for CVD prevention should be given to those at high risk, including:

  • Patients with established CVD and people with diabetes.
  • Healthy individuals identified at high risk using risk assessment tables, usually with main modifiable risk factors of smoking, hypertension and dyslipidaemia.
  • Close relatives of patients with premature CVD and dyslipidaemia.
  • Other individuals thought to be at high risk - especially the overweight/obese and the physically inactive.

Reducing the risk - prevention
The British Heart Foundation lists five steps to heart health:

  1. Healthy eating - follow a healthy, cardioprotective diet.
  2. Be more active - aim to take at least 30 minutes of exercise a day.
  3. Be smoke-free.
  4. Reduce alcohol, follow guidelines and avoid binge drinking.
  5. Trim excess weight through a combination of a healthy diet and increased physical activity.

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Government action - public health initiatives
Choosing a Better Diet: A Food and Health Action Plan highlights the importance of good nutrition to good health and the contribution of a poor diet to premature death from CVD and cancer.(5)
Research has shown that each increase of one portion of fruit and vegetables a day lowers the risk of CHD by 4% and stroke by 6%. It is estimated that by eating five portions of fruit and vegetables daily the risk of death from chronic diseases, including CHD and stroke, can be reduced by up to 20%. Ill-health attributable to poor diet costs the NHS around £4b per year.

The role of overweight and obesity
The increasing incidence of overweight and obesity in all age groups, including children, has put obesity management very near the top of the public health agenda. Any strategy to prevent or treat CVD must address weight management.
Obesity is closely linked with an increased risk of developing hypertension, hyperlipidaemia, type 2 diabetes and CHD. It is estimated to account for 9,000 premature deaths annually - 6% of all premature deaths compared with 10% for smoking.

Dietary guidelines
The diet recommendations for a general healthy diet are now very similar to the dietary guidelines for primary and secondary prevention of CVD. Previously, advice to CVD patients was solely symptom-linked - for example, patients with hyperlipidaemia were advised to follow a cholesterol-lowering diet with a reduced total and saturated fat content. This advice may have helped to reduce total and LDL-cholesterol, but also reduced protective HDL-cholesterol, which is obviously undesirable.
Little, if any, emphasis was placed on increasing the intake of the cardioprotective nutrients now known to be important in heart health. Dietary advice must be more comprehensive - focusing on what to eat, especially the protective nutrients, as well as what foods to avoid. The health benefits of eating a "Mediterranean"-style diet with supporting epidemiological evidence have led many to revise their dietary guidelines. The diet should be based around fruit, vegetables, fish and poultry, cereals (preferably wholegrains) and unsaturated fats, also including low-fat dairy products and modest amounts of lean meat.
Hooper et al have reviewed their evidence-based dietetic guidelines for the secondary prevention of CVD.(6) This review stresses the importance of ensuring that people with CVD are offered high-quality, evidence-based dietary advice to protect against further illness and death. Advice should include:

  • Increased omega-3 fat intake from dietary or supplemental fish oils.
  • Reduction in saturated fats and total or partial replacement by unsaturated fats such as rapeseed or olive oil.
  • Mediterranean dietary advice, which includes an increase in omega-3 fats (fish and vegetable sources), fruit and vegetables and fresh foods, and reduction in saturated fats and processed foods.

There is little or no evidence to suggest benefit from supplementation with antioxidant vitamins or garlic. Health professionals should focus dietary advice on food rather than dietary supplementation, with the exception of fish oils if fish is rarely or never consumed.

Dietary advice
Dietary advice should focus on risk factor reduction and needs to be appropriate and realistic, taking individual lifestyles into consideration. It is preferable to discuss diet with other lifestyle advice, especially increased physical activity, in the same consultation.
It is worth considering public attitudes to food and diet. A recent Institute of Grocery Distribution survey found that 61% of respondents already thought their diet was "healthy", and only 11% thought their diet was  "unhealthy".(7)
Around 50% recognised that eating five portions of fruit and vegetables daily was a major part of a healthy diet. Only 11% recognised the importance of balance. In 34% the desire to lose weight or prevent weight gain was the main catalyst to eating a healthy diet. Depressingly, only 9% said they would eat a healthy diet to prevent the onset of health problems.
This points out the important role for health professionals in offering clear and relevant advice highlighting how dietary change can improve disease risk and disease progression.

Reducing cholesterol
This comprises healthy heart advice with some emphasis on limiting total and saturated fat intake, and replacement with the healthier unsaturated fats - especially olive oil and rapeseed oil.
Cholesterol-rich foods such as eggs, offal and fish roes should be limited, but this advice needs to be put into the context of the whole diet, as significant effects of dietary cholesterol are only seen at high intakes. Soluble fibre-rich foods such as oats and pulses (beans and lentils) as well as cholesterol-lowering foods containing plant sterols or stanols have been shown to be especially effective at cholesterol reduction.

Fish and fish oils
Studies have shown the benefit of fish and fish oils in terms of secondary prevention. The cardioprotective diet contains three portions of fish per week, including one to two servings of an oil-rich fish such as salmon, sardines, mackerel and herrings.

Fruit and vegetables
Advice is to eat at least five assorted portions of fruit and vegetables daily.

Weight management
Realistic weight management targets need to be set. A modest weight loss of 10kg has significant health benefits, and this should be the first goal for the obese/overweight.
Dietary advice should be comprehensive and focused on what to eat as well as what food types to avoid and should be linked to advice to increase physical activity. The use of "faddy" and "quick-fix" diets should be discouraged. Slow and sustainable weight loss on a diet plan that includes foods from all the main food groups and promotes satiety is to be advocated.

Salt reduction
Current advice is to reduce daily salt intake to 6g - currently the average daily intake is around 9.5g. Almost 75% of our dietary salt comes from salty processed foods, with very little usually contributed by salt added in cooking or at the table. Salt reduction should help reduce population blood pressure levels and the incidence of stroke.

Alcohol
Drinking should be within current guidelines.

Understanding food labels
This can allow us to make informed choices about what foods to purchase. Guideline daily amounts (GDAs) are useful (see Table 1). As a rule, the main meal of the day should contain around 25% of the GDAs, and snacks should make up less than 10% of the GDAs. Useful advice is to choose meals with less than 15g total fat and 500mg sodium and snacks with less than 5g total fat and 300mg sodium.

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Conclusion
Foods can either promote or prevent CVD. There is now sufficient evidence as to the benefits of following a cardioprotective, "healthy heart" diet, and such advice should be readily available to all patients. Achieving dietary change will help improve the health of the nation.

References

  1. British Heart Foundation. Statistics. Available from URL: http://www.heartstats.org
  2. DH. National Service Framework for coronary heart disease. London: TSO; 2000.
  3. DH. Nutritional aspects of cardiovascular disease. Report on Health and Social Subjects No. 46. London: TSO; 1994.
  4. British Cardiac Society, British Hyperlipidaemia Association, British Hypertension Society. Heart 1998;80(S2):S1-29.
  5. DH. Choosing a better diet: a food and health action plan. London: TSO; 2005.
  6. Hooper L, et al.  J Hum Nutr Diet 2004;17:337-49.
  7. Institute of Grocery Distribution. Available at URL: http://www.igd.com/ CIR.asp?menuid= 38&cirid=1181

Resource
British Dietetic Association
W:www.bda.uk.com/Downloads/Julyfoodfacts.pdf