High Blood Pressure: Natural Self-help for Hypertension, including 60 recipes. Michelle Berriedale-Johnson

rise even further.

      As a result, the heart has to pump blood out into a circulation whose vessels are narrowed and have lost their elasticity. This increases the workload of the heart – which has to pump blood out into the high-pressure system – and its need for oxygen increases at a time when its blood supply is often already compromised due to atherosclerosis of the coronary arteries. As the heart muscle beats over 100,000 times per day, lack of oxygen rapidly leads to muscle cramping, making angina and a heart attack more likely. In some people, two-thirds or more of a coronary artery may be furred up and blocked without causing symptoms. In others, angina may be triggered even though only a small plaque is present and the coronary artery is narrowed only slightly. It all depends on:

       the exact site where the atheroma and narrowing have developed – the most common is within 3cm of where a coronary artery originates from the aorta, so the effects of ischaemia (lack of blood supply) are likely to be more widespread and serious

       how well the two main coronary arteries join up to share the load of supplying blood

       how good the blood supply from the other coronary artery is

       the type of coronary arteries you have inherited – whether they are the vascular equivalent of motorways or winding country lanes.

      Cholesterol Levels

      Fats from your food are processed in the small intestines to form fatty globules (chylomicrons) bound to carrier proteins, which together form substances known as lipoproteins. After a fatty meal, there may be so many of these fatty particles in the circulation that blood takes on a milky-white appearance. These fatty globules are cleared from your bloodstream by the action of an enzyme (lipoprotein lipase) found in the walls of blood capillaries. Some of the fat released in this way is taken up into cells, while some remains in the circulation and is transported to the liver. In the liver, the fats are processed, packaged to different types of carrier proteins and passed out into the circulation again for further distribution around your body.

      There are two main types of circulating cholesterol:

       low-density lipoprotein (LDL) cholesterol, which is linked with hardening and furring up of artery walls, high blood pressure and coronary heart disease

       high-density lipoprotein (HDL) cholesterol, which protects against atherosclerosis and CHD by transporting LDL-cholesterol away from the arteries for metabolism.

      Research shows that for every 1 per cent rise in beneficial HDL cholesterol, there is a corresponding fall in the risk of CHD of as much as 2 per cent. This seems to be due to reversed cholesterol transport in which HDL moves LDL cholesterol away from the tissues and back towards the liver.

      It is, therefore, not so much your total blood cholesterol level that is important when it comes to atherosclerosis but the ratio between beneficial HDL cholesterol and harmful LDL cholesterol. If you are told you have a raised blood cholesterol level, it is important to know whether your LDL or HDL cholesterol is high:

       if your blood fats consist mainly of HDL-cholesterol, your risk of CHD is significantly reduced

       if most of the lipids are in the form of LDL-cholesterol, with low HDL levels, your risk of CHD is significantly increased. Ideally, total cholesterol level should be less than 5mmol/l, with LDL cholesterol less than 3mmol/l.

      Where LDL cholesterol levels are raised, it is estimated that reducing the average total blood cholesterol level by 10 per cent could prevent over a quarter of all deaths due to coronary heart disease. Unfortunately, attempts to reduce dietary cholesterol for improved cardiovascular health often have the opposite effect. Rather than just lowering the potentially harmful LDL form of cholesterol, dietary interventions often reduce levels of beneficial HDL-cholesterol as well. This is because the types of fat in your diet are also important, and people often cut out the good fats as well as the less desirable ones. If you ate all your fat in the form of essential fatty acids, monounsaturated fats (e.g. olive oil) and fish oils, for example, your risk of CHD would be low as most circulating fats would be in the form of beneficial HDL-cholesterol.