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Transcript
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]