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News….. Cardiovascular Disease: Diet, Nutrition and Emerging Risk Factors 10 Key Facts 1. Cardiovascular disease (CVD), including heart disease and stroke, is the leading cause of death in the UK. The well recognised risk factors (smoking, raised blood cholesterol levels, elevated blood pressure, physical inactivity, obesity and type 2 diabetes) cannot explain all cases of heart disease. Recent research has identified a number of novel risk factors that may help to identify those at risk and additional approaches to tackle the condition. 2. Insulin resistance occurs when the cells in the body respond sluggishly to the action of insulin and can result in the development of type 2 diabetes. The insulin resistance syndrome (also known as syndrome X or the metabolic syndrome) refers to a combination of health problems including insulin resistance, abnormal levels of blood fats, obesity and high blood pressure. People with this syndrome are around 3 times more likely to die from CVD even after controlling for other risk factors. Eating a healthy diet, being physically active, not smoking, and drinking alcohol in moderation, can help to avoid all features of the syndrome. 3. Conventional lipid-related CVD risk factors include high blood levels of total and low-density lipoprotein (LDL) cholesterol, low levels of highdensity lipoprotein (HDL) cholesterol and elevated triglycerides. Although the total amount of fat consumed is important, accumulating evidence places greater emphasis on the importance of the types of fatty acids in the diet and the partial replacement of saturates with unsaturated fatty acids. High levels of lipoprotein (a) and remnant lipoproteins also appear to increase CVD risk. 4. The endothelium (the layer of cells lining the blood vessels) regulates the normal functioning of blood vessels and plays an integral role in the prevention of CVD. Abnormalities in its function can increase risk of heart disease. Dietary factors such as long chain n-3 fatty acids (EPA and DHA) (found predominantly in oily fish), Mediterranean style-diets and some vitamins appear to have beneficial effects on the endothelium. 5. Free radical damage has been implicated in the development of CVD and a number of antioxidant nutrients are important in the body’s defence systems. Diets rich in fruit and vegetables, which contain antioxidants such as vitamin C and beta-carotene, are associated with reduced CVD risk. However, human intervention trials using supplements of these nutrients have not generally shown any benefit. This might be because fruit and vegetables contain other compounds that are not present in supplements (e.g. flavonoids and sulphurcontaining compounds). In trials of high risk subjects, supplementation may have occurred too late in the development of the disease to reverse existing damage. 6. Raised concentrations of some of the substances involved in blood clotting (coagulation) (e.g. fibrinogen) or the breakdown of blood clots (fibrinolysis) seem to predict CVD risk. Being overweight, inactive, smoking and consuming a diet that is high in fat (particularly saturates) increases the risk of a blood clot forming. In contrast, moderate amounts of alcohol and high intakes of long chain n-3 fatty acids appear to reduce the tendency of blood cells to stick together to form a clot. 7. Prolonged inflammation within the walls of the arteries may contribute to atherosclerosis (narrowing and hardening of the arteries), which can elevate blood pressure and increase the risk of a heart attack or stroke. Levels of some markers of inflammation (e.g. C-reactive protein, fibrinogen) have been linked with CVD risk but whether these add anything of value over conventional markers of heart disease remains to be established. Currently there is insufficient evidence describing the effects of diet on these markers but the long chain n-3 fatty acids and some antioxidant nutrients seem to have anti-inflammatory effects. 8. High blood levels of homocysteine, an amino acid produced by the body, increase the risk of CVD. Several B vitamins are involved in homocysteine metabolism and supplementation with these vitamins (particularly folic acid and vitamins B6 and B12) lower homocysteine levels. Large clinical trials are underway to test whether lowering homocysteine levels through supplementation with these vitamins is effective in CVD prevention. 9. Adipose tissue (body fat) secretes substances (known as adipokines) that have been linked with a number of processes that contribute to the development of CVD, including hypertension, inflammation and insulin resistance. One of the most well known adipokines is leptin which is believed to play a role in appetite control.Weight gain and excess energy intake is associated with a rise in many adipokines, while weight loss and exercise is generally associated with a fall in blood levels of these substances. 10. Low birthweight and low weight gain during infancy are associated with an increased risk of adult CVD, hypertension, type 2 diabetes and insulin resistance syndrome. The ‘fetal origins of adult disease’ hypothesis proposes that these associations reflect permanent metabolic and structural changes resulting from undernutrition during critical periods of early development. An alternative explanation is that both reduced fetal growth and CVD risk factors have common genetic origins. Mothers should be encouraged to attain a healthy weight and to adopt a varied and balanced diet before and during pregnancy. However, further research is needed to identify exactly what aspects of a mother’s diet can influence the birthweight and subsequent disease risk of her offspring. The Task Force Report, Cardiovascular Disease: Diet, Nutrition and Emerging Risk Factors, is now available from the BNF priced at £47.50. Details of a special discounted price can be found on our website www.nutrition.org.uk Rebecca Foster, Nutrition Scientist and Sara Stanner, Senior Nutrition Scientist Notes: This is a summary of the findings from a British Nutrition Foundation conference held on the 12th April 2005 to launch the report of the Cardiovascular Disease: Diet, Nutrition and Emerging Risk Factors Task Force. Speakers were Prof. Keith Frayn (University of Oxford), Dr Simon Coppack (St Bartholomew’s and the London Royal Society of Medicine), Prof. Gordon Ferns (University of Surrey), Prof. Naveed Sattar (University of Glasgow), Dr Richard Bruckdorfer ((University College London), Dr Caroline Fall (University of Southampton) and Dr Judy Buttriss (British Nutrition Foundation). Prof. Robert Pickard (Director-General at the BNF) chaired the conference. The British Nutrition Foundation provides independent and authoritative scientific information on the relationship between food, nutrition and health. For more information visit our website www.nutrition.org.uk or contact us at High Holborn House, 52-54 High Holborn, London WC1V 6RQ.Tel: 020 7404 6504, Fax: 020 7404 6747, E-mail: [email protected]