The New theories 05-04-2006 1. Oxidation of LDL Toxic metals such as aluminium and lead, as well as iron and copper, when in excess, initiate free-radical production. These free-radicals oxidise low density lipoproteins (LDL), which are ingested by cells of your immune system called macrophages. These macrophages soon become stuffed with oxidised LDL and form new cells called foam cells. These foam cells then clump together leading to fatty deposits on the arterial walls which is the beginning of atherosclerosis. 2. Inflammation When your immune system is activated, inflammation takes place. This means that your body is heating up to defend itself against some impending threat which might be a parasite or bacteria, an environmental toxin, food allergy or any other source of danger. Sometimes the immune system gets confused and attacks your own body, for example in rheumatoid arthritis and other auto-immune diseases. in the case of ischaemic heart disease inflammatory cells of the immune system give off smaller cells called 'ICAMS' which are intracellular adhesion molecules. These infiltrate the arterial wall where they are gobbled tip by foam cells which in turn release oxidants which convert LDL to oxidised LDL. Oxidised LDL accumulates leading to the development of atherosclerosis. A blood test measuring c-reactive protein will some indication whether an inflammatory process is taking place in your body. 3. Insulin Until recently insulin was thought to be solely responsible for glucose and fat metabolism. What we know now is that raised insulin levels have a number of adverse metabolic and physiological consequences including elevated cholesterol and LDL levels, increased oxidative stress, decreased HDL and high blood pressure. If you are overweight, feel tired after a carbohydrate meal such as pasta or rice and have difficulty saying no to a packet of biscuits once you have commenced the first biscuit, chances are you have high insulin levels. A simple blood test measuring glucose and insulin before and after a carbohydrate challenge will inform you of the presence of this problem. 4. Lipoprotein (a) Linus Pauling has put forward the theory that more lipoprotein (a) is made when vitamin C is deficient which then travels to arterial walls depositing itself there. These lipoprotein (a) molecules thicken arterial walls, thereby resulting in cardiovascular disease. For survival of the species, it makes more sense to die from a heart attack after reproduction, than to die from scurvy before reproduction. 5. Homocysteine This protein has achieved major prominence as one of the primary new players in the cause of heart disease. There is now evidence that raised homocysteine levels are associated with ischaemic heart disease in 10-20 per cent of cases. In fact some studies have indicated that the risk of coronary artery disease increased by 70 per cent for each 5uml increase in homocysteine. Homocysteine is an amino acid and it is produced as the body processes proteins. Normally homocysteine is metabolised to a harmless by-product. In order to do this, certain vitamins are necessary and these are vitamins B6, B1, and folic acid. These vitamins are derived from leafy green vegetables and fruit and it comes as no surprise that up to 40 per cent of the population may be deficient in these, leading to raised homocysteine levels. Homocysteine is a potent inducer of atherosclerosis and causes visible damage to blood vessels at a very early stage. Certain individuals also have a genetic propensity to elevated homocysteine. 6. Vitamin E Low rates of ischaemic heart disease are associated with high dietary vitamin E levels. Vitamin E is thought to play a role through inhibition of oxidation of LDL. In a large experiment performed in the United Kingdom supplements of vitamin E, given in levels exceeding those that may be obtained from dietary sources alone, significantly reduced the incidence of ischaemic heart disease and heart attacks. This was achieved in some patients who had advanced atherosclerotic lesions indicating that if indeed oxidation of LDL is the culprit this can be reversed by high dose antioxidants. 7. Low magnesium Magnesium deficiency is associated with all the manifestations of heart disease including irregular heart beat, increasing atherosclerosis, spasm of the arteries, raised blood pressure and heart attack. Magnesium insufficiency is not something that is generally thought of as important or even likely. However the foods that are highest in magnesium - vegetables (especially legumes and dark green vegetables), whole grains and nuts are not major constituents of the Australian diet. Nutrients that are high in the diet including saturated fat, sugar, salt and alcohol, all increase the dietary need for magnesium. Aging and stress also augment magnesium requirements. Magnesium supplementation has been shown to lower blood pressure and prevent the development of atherosclerosis by reducing total cholesterol and raising HDL. In brief, oxidised LDL, inflammation, raised insulin levels, elevated lipoprotein (a), excess homocysteine and reduced magnesium levels are all risk factors for the development of heart disease. This explains why some individuals with normal cholesterol are in danger of having a heart attack and that other factors need to be considered when you have your cardiovascular status evaluated. 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