Smoking, high blood pressure, high blood cholesterol and a poor diet increase the risk of cardiovascular disease.SmokingCarbon monoxide has a higher affinity for haemoglobin than oxygen and combines irreversibly with haemoglobin. This reduces the oxygen-carrying capacity of the blood and raises the blood pressure.Nicotine stimulates the production of adrenalin which increases the heart rate and raises the blood pressure. Nicotine also makes blood platelets more sticky increasing the risk of thrombosis. This can lead to myocardial infarction or stroke.High Blood PressurePeople may be genetically predisposed to high blood pressure but the risk increases with prolonged stress, poor diet and lack of exercise. The heart has to work harder and therefore is more prone to failure, the artery walls may weaken (aneurysm) and burst causing a haemorrhage or the walls may become thickened and hardened restricting the flow of blood.High CholesterolCholesterol is an essential component of membranes and a precursor for steroid hormones. It is transported from the tissues to the liver for excretion as high density lipoproteins(HDLs) which are protective against heart disease. LDLs transport cholesterol from the liver to tissues. They may infiltrate the artery walls leading to atheroma and heart disease.Poor DietHigh levels of salt raise blood pressure. High levels of saturated fat increase low density lipoproteins.