Eat to Beat High Blood Pressure
Natural Self-help for Hypertension, including 60 recipes

Dr Sarah Brewer and Michelle Berriedale-Johnson

Contents

Cover

Title Page

Introduction

Part One: The Facts about High Blood Pressure

Chapter 1: What is High Blood Pressure?

Chapter 2: Causes, Diagnosis and Treatment of High Blood Pressure

Part Two: High Blood Pressure and Diet

Chapter 3: Atherosclerosis, Cholesterol and Dietary Fats

Chapter 4: High Blood Pressure and Olive Oil

Chapter 5: High Blood Pressure and Oily Fish

Chapter 6: High Blood Pressure, Folic Acid and Homocysteine

Chapter 7: High Blood Pressure and Salt

Chapter 8: High Blood Pressure, Fruit and Vegetables

Chapter 9: High Blood Pressure and Garlic

Chapter 10: High Blood Pressure and Tea

Chapter 11: High Blood Pressure and Red Wine

Part Three: The Recipes

Chapter 12: Introduction

Chapter 13: Soups and Starters

Chapter 14: Fish

Chapter 15: Meat and Poultry

Chapter 16: Vegetables and Vegetarian Dishes

Chapter 17: Desserts

Chapter 18: Baking

Part Four: Taking it Further

Chapter 19: High Blood Pressure and Food Supplements

Chapter 20: High Blood Pressure and Healthy Weight

Chapter 21: High Blood Pressure and Lifestyle

Useful Addresses

Index

Copyright

About the Publisher

Introduction

Whether or not you develop high blood pressure (hypertension) is influenced by several factors. These are your genes, the way you eat, and other aspects of your lifestyle such as the amount of exercise you take, whether or not you smoke, and the amount of alcohol you drink. Eating to beat high blood pressure is not only possible, it is one of the mainstays of effective treatment. This book looks at how various dietary changes can help to reduce a raised blood pressure and lessen your risk of developing associated complications such as coronary heart disease and stroke.

Making simple, healthy changes to your lifestyle can also significantly reduce your chances of contracting coronary heart disease. For instance, if you stop smoking, your risk of getting heart disease drops by 50–70 per cent within five years. If you take up regular exercise, your risk falls by 45 per cent. Keeping your alcohol intake within healthy limits will also have a beneficial effect. Drinking two or three units a day can reduce your chances of heart disease by as much as 25–45 per cent, but excessive intakes increase the risk. Losing excess body weight will bring your chances of heart disease down by 35–55 per cent. For more on lifestyle changes, see Chapters 20 and 21.

Food supplements are also effective in helping to maintain a healthy circulation. For more about these, please see Chapter 19.

The delicious recipes provided by Michelle Berriedale-Johnson will make eating to beat hypertension as pleasant and easy as possible.

PART ONE The Facts about High Blood Pressure

CHAPTER 1 What is High Blood Pressure?

Everyone needs a certain blood pressure (BP) to keep blood moving around their body and maintain their circulation. Blood pressure exists because your heart pumps blood around a closed system, rather like a boiler pumping water through a series of central heating pipes. The pressure in your arteries therefore depends on a number of factors, including the volume of fluid inside your circulation, how hard your heart is pumping at any given time, and the elasticity or ‘resistance’ of the vessels the blood is passing through.

Normal BP varies naturally throughout the day and night, going up and down in response to your emotions and level of activity. If you have high blood pressure, however, your BP will remain consistently high, even when you are asleep.

The heart alternately contracts and relaxes as it pumps to produce the heartbeat. Each contraction produces a surge in pressure. The highest pressure reached in the arteries during this surge is known as the systolic pressure as it is due to contraction (systole) of the heart. As the heart rests between beats, blood pressure falls again and the lowest blood pressure recorded while the heart rests (diastole) is known as the diastolic pressure. In general, as the heart pumps more strongly, systolic pressure rises, while a reduction in elasticity of the peripheral arteries causes diastolic pressure to go up.

How BP is Measured

Blood pressure (BP) is measured using an instrument called a sphygmomanometer. This has an inflatable cuff which goes around your upper arm, a small pump to push air into the cuff and a column of mercury (or a dial) to record the pressure within the cuff.

As the cuff is inflated with air, the person measuring your BP usually feels for a pulse (brachial artery) in the crook of your elbow. While the pressure within your artery stays higher than that in the cuff, blood can be felt pulsing through. Once the pressure in the cuff becomes greater than that in your artery, the vessel is squashed flat and blood stops flowing through it at that point. By inflating the cuff to an initial pressure that is higher than the expected systolic pressure, then listening with a stethoscope over your brachial artery as the pressure is slowly released, the point at which blood manages to squirt through again with each pulse can be heard distinctly as a tapping sound. The pressure registering in the cuff at this point is taken as your systolic BP. The cuff is then slowly deflated further while listening over your artery. The tapping sounds become louder, then change to a dull whooshing noise before disappearing. The point at which blood can no longer be heard whooshing through the vessel is taken as your diastolic BP. The pulsing noise heard in the artery between these two pressures is a result of turbulence as the cuff impinges on the vessel and deforms its walls. We therefore know that the blood pressure in the artery is the same as that in the cuff at the point where the sounds disappear, as turbulence is no longer occurring. BP can also be measured with modern digital cuffs that fit around the wrist.

BP is measured according to the length of a column of mercury it can support. It is therefore expressed in millimetres of mercury (mmHg). BP is written down as the higher pressure (systole) over the lower figure (diastole).

A typical 20-year-old may have a BP of around 120/70 mmHg.

BP naturally tends to rise with age and a fit 50-year-old may have a BP of around 135/85 mmHg.

The pulse pressure – the difference between the systolic and diastolic pressures – is normally around 50 mmHg.

If your BP is consistently higher than 140/90, then you are suffering from high blood pressure, or hypertension.

How Blood Pressure is Controlled

Blood pressure is normally controlled and kept within safe limits by the body in a number of ways, including:

changing the rate at which the heart pumps

widening or constricting small arteries

altering the amount of blood pooled in the veins

varying the amount of salt and fluids filtered from the circulation via the kidneys.

These factors are controlled by nerve signals from the brain, and by several different hormones. As a result, normal BP varies naturally throughout the day, going up and down in response to your emotions and level of activity. It is lowest during sleep (usually at around 3am) and highest in the morning from just before you wake until around 11 am. If you have high blood pressure, however, your BP will remain high all the time, even at rest.

Hypertension

As many as one in five adults have high blood pressure, known medically as hypertension. This means that blood is forced through their system under a constantly high pressure. Hypertension is diagnosed when systolic pressure is consistently greater than 140 mmHg and diastolic pressure consistently greater than 90 mmHg. A systolic blood pressure between 140–160 mmHg and diastolic values between 90–95 mmHg are sometimes referred to as mild hypertension.

In hypertension, the body’s systems for correcting high or low blood pressure don’t seem to work properly so blood pressure is maintained at an elevated level compared to normal. Little is known about how or why this happens, but the condition seems to be readily reversible once diet and lifestyle changes are introduced, together with any necessary anti-hypertensive drug treatment.

SYMPTOMS

Unfortunately, people with high blood pressure usually notice very little in the way of symptoms, although a few may develop a pounding sensation in their ears or a splitting headache. As a result, hypertension is often referred to as the silent killer, as it usually creeps up on you without any obvious warning. Even if your blood pressure is dangerously high, you may feel relatively well. If symptoms do occur, they tend to be non-specific, such as a headache or getting up at night to pass urine more often than normal. Your blood pressure has to be severely raised before you develop dizziness or visual disturbances. It is therefore a good idea for adults to have their blood pressure checked on a regular basis, every year or so – especially if high blood pressure runs in their family. This is because a high blood pressure that remains undiagnosed and untreated can lead to a number of potentially serious complications.

WHY HIGH BLOOD PRESSURE IS HARMFUL

Hypertension is not a disease in itself, but a clinical sign that you are at increased risk of a number of serious health problems. As blood is forced through your system at high pressure, your artery walls receive a pounding. This which can both over-stretch important blood vessels as well as damage their linings. If left untreated, this can trigger premature hardening and furring up of the arteries (atherosclerosis) and increase the risk of a number of health problems. If your blood pressure remains constantly high, this can lead to:

peripheral vascular disease – when arteries supplying blood to the limbs become hardened and furred up so circulation is reduced

impotence – when the blood supply to the penis is affected

failing sight – when blood vessels in the eyes are affected

kidney failure – when blood vessels in your kidneys are damaged

heart failure – when your heart finds it difficult to pump blood against the high pressure in your circulation; this typically causes breathlessness as fluid builds up in your lungs

angina (heart pain) – when the excess workload on the heart increases its oxygen and nutrient needs beyond those provided by its blood supply

a heart attack – when the coronary arteries are damaged enough to trigger a sudden blockage of blood supply to the heart muscle (e.g. due to a blood clot)

a stroke – when blood vessels in the brain are damaged enough to cause a disruption in blood supply to brain cells, – either due to a sudden blood clot, or to a haemorrhage.

Research shows that for a man in his 40s:

each rise in systolic blood pressure of 10mmHg increases his risk of heart disease by 20 per cent

the risk of having a stroke is 30 times higher if he has high blood pressure than for someone with normal BP.

This all sounds rather frightening, but the good news is that early diagnosis and treatment can control your blood pressure and keep you healthy. It is vitally important that your hypertension is well controlled, by taking your tablets exactly as prescribed. A number of relatively simple dietary and lifestyle changes can also help to reduce the risk of high blood pressure, lower a BP that is already raised and reduce the risk of complications such as coronary heart disease. If these changes were to reduce your diastolic BP by as little as 5 mmHg, they would decrease your risk of coronary heart disease by 16 per cent, and if they succeeded in reducing your average blood pressure by 10 mmHg, this would reduce your risk of premature death by as much as a third. You really can eat to beat the unwanted effects of high blood pressure.

UNDIAGNOSED HYPERTENSION

Ideally, all adults should have their blood pressure measured regularly, at least once every three years, or more often as your doctor recommends. If your blood pressure is found to be high, you will have it measured several times before your doctor decides whether or not to prescribe any anti-hypertensive drugs. This is to make sure your blood pressure remains consistently high and is not just going up as a result of visiting the surgery. Once you start taking blood pressure treatment, you may be on it for life – but you will probably live longer as a result.

Unfortunately, an estimated one in two people with high blood pressure are undiagnosed, and of those that are picked up and treated, at least another half do not have acceptable blood pressure control. This is mostly because the condition rarely makes you feel ill, and having to take one, two or even three tablets per day to treat something that is not an illness, but a risk factor for other diseases, is understandably frustrating. However, early diagnosis and successful treatment of high blood pressure is vital for continued long-term health.

Types of High Blood Pressure

Ninety per cent of people with high blood pressure, have no obvious single cause and are said to have primary, or essential, hypertension. The remaining one in ten people with high blood pressure have an identifiable underlying factor, such as kidney problems, a hormone imbalance or drug side-effects, and are said to have secondary hypertension.

Malignant hypertension refers to the most dangerous type of high blood pressure in which pressures go very high, often very quickly. This can damage internal organs over a short period of time and is sometimes also referred to as accelerated hypertension. It is treated as a medical emergency because if diastolic pressure remains above 120 mmHg for a prolonged period of time, the linings of small blood vessels (arterioles) are damaged and start to leak. When looked at under the microscope, the blood vessel walls have literally started to crumble (fibrinoid necrosis). This lets protein-rich fluid, and sometimes whole blood, seep out of the blood stream to build up in the tissues. As well as interfering with blood supply to that part of the body, the leakages cause damage, inflammation and scarring – commonly to the kidneys, backs of the eyes and in the brain. This is known as target organ damage. Damage to the kidneys also results in the release of hormones that put the blood pressure up even more, so a vicious cycle builds up. Treatment aims to bring BP down slowly over several days so that the body can adjust to lower pressures again.

To differentiate it from malignant hypertension, primary high blood pressure is often referred to as benign essential hypertension.

Refractory hypertension refers to high blood pressure that does not respond to standard first-line anti-hypertensive drug treatments. Although this is uncommon, referral to a specialist is needed so that investigations and treatment with other drugs can be started.

CHAPTER 2 Causes, Diagnosis and Treatment of High Blood Pressure

Blood pressure naturally tends to rise with age, so that high blood pressure is more common in middle life and beyond. Some people, especially males, may develop it in their 20s or even earlier, however. Blood pressure is also known to vary with race – those of African origin tend to have higher blood pressures than Caucasians, for example.

Causes of Essential Hypertension

Several factors are thought to be involved in the development of primary, or benign essential hypertension. These include inherited factors (high blood pressure runs in some families), developmental factors (occurring during embryonic life in the womb) and environmental factors such as diet and lifestyle, which you can address to help lower a high blood pressure.

INHERITED FACTORS

Essential hypertension is thought to result from inherited genes that may trigger high blood pressure as a result of one or more abnormalities involving:

sensitivity of the blood pressure monitors (baroreceptors) throughout the circulation

altered secretion of, or sensitivity to, hormones (e.g. anti-diuretic hormone, renin, aldosterone) or other chemicals that help to regulate normal blood pressure

dilation or constriction of blood vessels in response to pressure changes

nerve control of BP or abnormal signals from the brain

control of the amount of fluid and salt in the circulation

control of the strength and rate of the heartbeat.

Researchers have already identified a gene that may be able to predict your future risk of hypertension. People who have inherited the angiotensinogen gene (T235) from both parents have double the risk of developing high blood pressure and coronary heart disease compared to those who do not have the gene variant, or who inherit it only from one parent.

DEVELOPMENTAL FACTORS

Fascinating research has suggests the way you develop during the first few weeks of life as an embryo may affect your future risk of high blood pressure and other cardiovascular diseases in adult life. This is probably linked with lack of micronutrients (vitamin and minerals) in the mother’s diet, which affects the way your arteries are laid down. Researchers have found, for example, that:

Low birth-weight babies maybe more likely to develop high blood pressure as adults. Average adult systolic BP increases by 11 mmHg as birth weight goes down from 7.5lb to 5.5lb.

The size of the placenta may be important – average systolic blood pressure rises by 15 mmHg as placental weight increases from 1lb to 1.5lb.

The highest blood pressures occur in men and women who were born as small babies with large placentas.

Risk of high blood pressure in later life also increases:

– as a baby’s birth length decreases

– as the ratio of a baby’s head circumference to the length of the baby increases from less than 0.65 to 0.7 or more.

– if the mother’s blood haemoglobin level was low during pregnancy

– if maternal nutrition was known to be poor.

Lack of important nutrients – including vitamins, minerals and essential fatty acids – during the first few weeks of embryonic life is thought to trigger the development of abnormal arterial and blood circulatory patterns. These probably result from an imbalance between the placenta and baby. This is supported by research linking fingerprint patterns with the risk of developing high blood pressure in later life. Fingerprints are laid down in the womb in the first few weeks following conception. Their patterns are linked to the degree of bumpiness and swelling of the developing fingertips, which is related in turn to irregular blood circulation.

Fingerprint patterns take the form of arches, loops or whorls, and the more whorls you have, the more likely you are to become hypertensive in later life. People with at least one whorl may have a blood pressure that is 6 per cent higher (8mmHg) than people with no whorls. BP then generally increases as the number of whorls increases, up to the maximum number possible, which is ten (two per digit). The average number tends to be two or three. Long, narrow hands are also associated with higher blood pressure, and both effects are more marked on the right hand.

Inherited and developmental factors are not the sole causes of high blood pressure, however. Something else has to happen in any individual before blood pressure goes up, and this is where environmental factors come in. These interact with inherited factors in individuals whose genes predispose them to hypertension to produce high blood pressure in later life. If several environmental factors linked with high blood pressure interact together, your risk of high blood pressure will be even greater.

ATHEROSCLEROSIS

One of the main causes of high blood pressure – especially a raised systolic BP – is hardening, furring up and narrowing of the arteries (atherosclerosis – see Chapter 3). This occurs naturally with increasing age and comes on more quickly if you smoke, eat an excessively fatty diet or are overweight. High blood pressure in turn puts excessive strain on the arterial wall lining and triggers damage that hastens atherosclerosis. Because atherosclerosis in turn causes hardening of arterial walls, a vicious cycle is set up in which blood vessels become even less elastic and less able to distend to even out pressure surges, so BP rises further. High blood pressure is therefore both a cause, and a consequence, of atherosclerosis, with each factor making the other worse.

DIABETES

Diabetes mellitus is a condition in which blood sugar (glucose) levels are raised due to insufficient production of insulin hormone by the pancreas. Some people also have an impaired tolerance to glucose tolerance due to an inability of their cells to respond properly to relatively normal levels of insulin (insulin resistance). Having poorly controlled diabetes significantly increases the risk of developing atherosclerosis, high blood pressure, coronary heart disease (CHD) and stroke – especially in women. The reason is not fully understood, but high blood sugar levels may trigger abnormal blood clotting, damage blood vessel linings to trigger hardening and furring up, affect nerves controlling heart and blood vessel function or weaken muscles in the heart or artery walls.

The risk of severe CHD is two to three times higher in men with diabetes and three to seven times higher in women with diabetes. Therefore, if you have both high blood pressure and are also diabetic, it is vitally important that you keep your blood sugar levels under tight control.

SMOKING

Smoking cigarettes greatly increases the risks associated with hypertension – people with high blood pressure, who also smoke, are two or three times more likely to develop coronary heart disease than hypertensive non-smokers, and life-insurance companies load their premiums accordingly.

Smoking cigarettes triggers hardening and furring up of the arteries (atherosclerosis), which is one of the most important causes of high blood pressure, coronary heart disease and stroke. It is also linked with at least 90 per cent of all cancers. The reason that cigarette smoke is so toxic is that it contains chemicals that:

damage the lining of arterial walls, triggering the build-up of clots and plaques

increase the stickiness of blood, making serious blood clots (thrombosis) more likely

displace oxygen from red blood cells in exchange for poisonous carbon monoxide – so that less oxygen is available for use by cells, including those in the heart muscle and artery walls

trigger spasm of arteries all over the body, which increases blood pressure and decreases blood flow to vital areas such as the brain and heart

produce harmful by-products of metabolism known as free radicals which damage tissues, increasing the risk of atherosclerosis and also of cancer.

For more information, see Chapter 21.

OBESITY

People who are overweight or obese are more likely to have high blood pressure than thin people, as there is a larger body tissue mass through which the heart has to pump blood. Overweight people are also more likely to eat an unhealthy diet with a high intake of saturated fat. This raises blood fat levels, which in turn hastens the onset of atherosclerosis. Another factor is that overweight people tend to be inactive.

Although not everyone who is overweight has high blood pressure, however, there seems to be an interaction between obesity and some underlying, predisposing mechanism that is inherited by some people. This may be linked to where excess fat is stored. Overweight people who carry excess weight around their middle (apple-shaped) rather than around their hips (pear-shaped) seem to be at greater risk of a number of health conditions, including high blood pressure, atherosclerosis, raised cholesterol levels, diabetes, CHD and stroke. The reasons are not fully understood but may be linked to the way the body metabolizes dietary fats.

For more information, see Chapter 21.

ALCOHOL

A high alcohol intake is also linked with an increased risk of hypertension. People who regularly consume excessive amounts (more than 3 units of alcohol per day, or 21 units per week) tend to have higher blood pressures. However, many people drink more than this and have a normal blood pressure – it depends on whether you have inherited predisposing factors that make you sensitive to these effects of alcohol.

For more information, see Chapters 11 and 21.

LACK OF EXERCISE

Lack of exercise is an important cause of high blood pressure. Inactivity means the heart is unfit, despite having to work extra hard to pump blood around the increased bulk of the body. People who exercise for at least 20–30 minutes, three times per week, have a lower risk of high blood pressure, stroke, obesity and coronary heart disease than those who are physically inactive.

To be beneficial, exercise needs to be brisk enough to raise your pulse rate, produce a light sweat and to make you slightly breathless. Unfortunately, the average level of physical activity in the UK is low. Only 30 per cent of men and 20 per cent of women are active enough to gain some protection against high blood pressure. One survey among adult males found that one in five had taken no exercise at all during the preceding month. Although exercise increases the amount of blood pumped through the heart by up to 700 per cent, and puts BP up during the period of exercise itself, this is a healthy, temporary response.

Taking regular exercise helps to prevent high blood pressure by:

burning off stress hormones that trigger arterial spasm in small blood vessels

dilating peripheral veins

increasing the efficiency of your cardiovascular system so your pulse rate falls

boosting the muscle pump action of your skeletal muscles

lowering blood fat levels

reducing the risk of atherosclerosis.

For more information, see Chapter 21.

STRESS

High blood pressure is thought to be linked with excessive levels of stress in some people. Susceptible individuals have an overactive part of the nervous system (sympathetic nervous system) which is unusually responsive to stressful stimuli that would normally be associated with only a mild, temporary rise in blood pressure. This overactivity of sympathetic nerves probably runs in families, with stress acting as the environmental factor that triggers off the process.

In people sensitive to stress, a condition known as Gaisbock’s syndrome can occur. This is a form of labile hypertension in which blood pressure levels can vary considerably. Sometimes they are high; sometimes they are low or normal. This can lead to more permanent hypertension if their lifestyle doesn’t slow down. One of the most common signs of this is so-called White Coat Hypertension – blood pressure that shoots up on being measured in the surgery or hospital (usually by someone wearing a white coat or uniform). This can increase systolic BP by as much as 100 mmHg, although this is extreme. More commonly, white coat hypertension increases systolic BP by 20–30 mmHg. This form of hypertension is confirmed by attaching the sufferer to a 24-hour BP monitoring tape and showing that BP rises in stressful conditions, including having BP measured by a doctor, then falls again in between.

Until recently, white coat hypertension was thought to be relatively harmless. However, latest research suggests that people with this condition have just as many abnormalities of the heart and blood vessels (e.g. poor left ventricular function, decreased elasticity and increased stiffness of artery walls) as those with persistently high blood pressure. They are also likely to develop hypertension in the future.

In most people, however, stress only causes only a transient rise in BP as a result of the hormone adrenaline (epinephrine). This triggers the constriction of arteries and veins which temporarily puts blood pressure up. This is an adaptive response to help you fight or flee in dangerous situations. Blood pressure can still fall when you are at rest or asleep, however, and relaxation training is usually helpful in offsetting the effects of excessive stress.

For more information, see Chapter 21.

KELOIDS

Interestingly, people who develop an excessive scar tissue reaction to a skin wound and produce a large, lumpy, keloid scar seem to be twice as likely to develop high blood pressure as people who produce normal amounts of scar tissue. This is thought to be due to a blood protein, angiotensin II, which helps to regulate blood pressure. It is now also known to stimulate production of collagen – a fibrous protein found in scar tissue. A group of drugs that block angiotensin (angiotensin converting enzyme – or ACE-inhibitors) are commonly used to treat high blood pressure. The link is the result of much research in an attempt to unravel some of the mysteries of essential hypertension.

For more information on dietary factors affecting essential hypertension, such as increased salt intake, and low intakes of calcium, magnesium, folic acid and antioxidants, see Chapters 6, 7, and 12.

Causes of Secondary Hypertension

One in ten people with hypertension have a recognizsed, underlying cause and are said to have secondary hypertension. Secondary hypertension should always be ruled out in any hypertensive person, but it is especially important to exclude other conditions in people developing high blood pressure before the age of 35.

KIDNEY DISEASE

The commonest cause of secondary hypertension is kidney disease, which accounts for 8 out of 10 cases. High blood pressure can also be the cause of kidney disease, however, and it can be difficult for doctors to tell which condition developed first. When high blood pressure is the cause of kidney disease, this occurs because essential hypertension leads to hardening and furring up of the large renal arteries and also damages small blood vessels in the kidney. As a result, blood supply to the kidneys is reduced and they may start to shrink. At the same time, poor blood supply to the kidney filtering units (nephrons) means less urine is produced. Kidney function progressively deteriorates and fluid builds up in the circulation, contributing to hypertension. Poor blood supply to the kidneys also stimulates the special pressure receptors (baroreceptors) in the kidneys that are responsible for monitoring blood pressure. If they detect blood pressure has fallen within the kidneys, they trigger increased production of renin hormone, which raises blood pressure in an attempt to increase blood supply to the kidneys. This puts BP up even more, so another vicious cycle develops.

Where kidney disease comes first, and high blood pressure develops as a consequence, the usual kidney diseases involved are:

chronic glomerulonephritis (inflammation of the kidney filtration units)

chronic atrophic pyelonephritis (shrinking of kidney tissue due to chronic infection or inflammation)

congenital polycystic kidneys (abnormal kidney structure due to the formation of multiple cysts during embryonic development).

Kidney problems are thought to cause high blood pressure by reducing filtration of excess fluid and salts from the body, which build up in the circulation to raise blood pressure. Increased secretion of renin hormone is also involved.

OTHER CAUSES

Other relatively common causes of secondary hypertension include:

pre-eclampsia during the last three months of pregnancy (which affects around one in ten pregnant women)

the side-effects of some drugs.

Rarer causes of secondary hypertension include:

anatomical abnormalities of the circulatory system such as narrowing of the aorta or renal artery

polycythaemia, in which blood stickiness is significantly increased due to over-production of red blood cells

Conn’s syndrome, in which there are high levels of aldosterone hormone

phaeochromocytoma, due to a tumour that secretes excessive amounts of adrenaline hormone and noradrenaline

Cushing’s syndrome, due to excessive exposure to corticosteroids – either from overactive adrenal glands or from steroid drug treatment

acromegaly, due to excessive production of growth hormone by the pituitary gland

hyperparathyroidism, due to overactivity of the four parathyroid glands in the neck which, if not treated, raises blood calcium levels and can damage the kidneys.

SECONDARY HYPERTENSION DUE TO DRUGS

Several drugs – both those available on prescription and those bought over the counter – can put your blood pressure up while they are being taken. These include:

nasal decongestants (e.g. ephedrine), taken to relieve a blocked nose

non-steroidal anti-inflammatory drugs (e.g. ibuprofen), taken to relieve aches and pains in the muscles and joints which – can raise BP by 5–10 mm Hg

oral corticosteroids, taken for severe inflammatory conditions such as asthma or rheumatoid arthritis

the combined oral contraceptive pill (containing both oestrogen and progestogen hormones), which can raise BP after several years’ use – recent research suggests that the average increase in BP is around 2.8/1.9 mmHg. In some women, however, rapid and more severe rises in BP can occur

monoamine-oxidase inhibitors – drugs sometimes used to treat severe depression – can cause sudden rises in BP if you eat cheese or other foods containing tyramine while on medication

carbenoxolone – a synthetic version of liquorice, sometimes used to treat stomach ulcers – can put BP up as it can trigger retention of sodium and water; a similar effect can also occur if you eat too much liquorice which has not been deglycerrizhinated.

Diagnosing High Blood Pressure
ROUTINE EXAMINATIONS

If your doctor finds your blood pressure is raised, you will probably have the following examinations:

checking your blood pressure at least twice during the first visit

feeling your pulse to see how regular and strong it is

checking pulses in your groin, feet and ankles to make sure your peripheral circulation is intact – pressing on the skin of your lower legs and then letting go will show how quickly blood flows back into the blanched area

feeling your chest to see where the tip of your beating heart is detectable – this gives a good indication of whether or not your heart is enlarged

listening to your heart with a stethoscope to check for heart murmurs and to listen to your heart beat rhythm

listening to your lungs to check for signs of fluid build-up on the chest

listening to your neck and abdomen with a stethoscope to detect any noises due to turbulent blood flow through damaged carotid or renal arteries

examining the backs of your eyes to look for any signs of arterial damage (see below).

If your blood pressure remains consistently raised, you may have the following routine investigations:

chest x-ray – to check the size and shape of the heart and to look for evidence of congestive heart failure with fluid build-up on the lungs

ECG – heart tracing to look for signs of left-ventricular thickening, irregular heartbeat or evidence that the heart muscle is struggling

analysis of a urine sample – to look for protein and sugar, which would suggest blood vessels in the kidney are damaged

blood test for urea and electrolytes – to check kidney function and your salt balance

blood test for fasting blood lipids – to see if your blood cholesterol or other fat levels are raised.

If your doctor suspects your blood pressure is due to an underlying cause, you may have one or more of the following tests carried out:

If your potassium level is low, and you are not on diuretic treatment, you may have a hormone problem leading to high blood pressure. You will therefore have blood tests taken to check levels of other hormones such as aldosterone, cortisol and renin.

Blood tests to assess kidney function (creatinine clearance rate).

An intravenous urogram – a substance that shows up on x-ray is injected into your blood stream and a series of x-rays taken. This shows any narrowing of your renal arteries, how well your kidneys concentrate the dye in the urine, and outlines your urinary system to show up anatomical abnormalities or shrinkage of the kidneys.

Ultrasound of your kidneys.

Blood tests to measure catecholamine levels or measurement of urinary vanillylmandelic acid if phaeochromocytoma (tumour of the adrenal gland) is suspected.

If acromegaly is suspected from changes to your facial features and the fact that your tongue, jaw, hands and feet are getting bigger, you will have your blood levels of growth hormone measured.

EYE EXAMINATIONS

High blood pressure damages small arteries throughout your body. Those in the back of the eye have the advantage of being visible using an ophthalmoscope and they show the state of arterioles throughout your system, including your brain. Early changes due to hypertension include thickening of retinal blood vessel walls. If hypertension becomes long-standing or severe, the blood vessels leak and little haemorrhages form. Other changes are probably due to obstruction of vessels and reduced blood circulation.

Your doctor will regularly check the back of your eyes for signs of damage if your blood pressure has been high. This is performed in a darkened room using an ophthalmoscope, which contains a number of lenses and a light source. Sometimes you may have one eye dilated first with drops to make the task easier. The doctor is looking for various abnormalities known as Keith-Wagener retinal changes. These are divided into four stages of severity:

Grade 1 – retinal arteries are more tortuous i.e. less straight. Because they are thickened and bulging under pressure, they also reflect light from the ophthalmoscope more than usual. This gives them an appearance known as silver wiring.

Grade 2 – as in grade 1, plus evidence that the thickened, bulging arteries are compressing the veins where they cross over them (arterio-venous nipping).

Grade 3 – as in grade 2, plus signs that the arteries have started leaking. Leakage of protein-rich fluid produces white, soft, ‘cotton wool’ – like blobs while leakage of blood produces flame-shaped haemorrhages.

Grade 4 – as in grade 3, plus swelling, bulging and blurring of the head of the optic nerve (papilloedema).

If haemorrhages, exudates or papilloedema are visible in the back of the eye, it shows that malignant hypertension (see page 5) has developed. These are the same sort of processes that are occurring in the brain and which are thought to lead to a stroke. It is very important that your hypertension is brought under control quickly and safely. You may be admitted to hospital for complete bed rest while your drug treatment is adjusted.

Peripheral Vascular Disease

Hardening and furring up of the arteries throughout the body can lead to peripheral vascular disease in which blood supply to your legs is severely limited. Even a mild increase in exercise means that your muscles need extra blood and oxygen – if these cannot be supplied, your leg muscles will start to cramp. This causes a severe pain in the calf muscles which comes on during exercise and stops when you rest – a condition called intermittent claudication. If your blood supply is severely affected, even walking 100 metres or less on the flat can bring symptoms on. If blood supply is very poor, ischaemic pain may occur at rest, tissues may break down to form a leg ulcer and eventually gangrene may set in. Severe peripheral vascular disease is most likely in someone with hypertension who also smokes, or who also suffers from diabetes.

Aspirin will help to thin the blood and improve blood supply. Some tablets also work by increasing the flexibility of red blood cells so they can squeeze through small blood vessels more easily. Interestingly, research shows that taking garlic powder tablets, ginkgo biloba or a mix of Tibetan herbs known as Padma 28 can improve peripheral circulation enough to increase the distance you can walk before calf pain starts by up to 30 per cent in three months (see Chapter 19).

A severely narrowed artery in the leg can be overcome with a bypass graft to open up an alternative circulatory route. If there are only one or two main sites of blockage, these can sometimes be overcome by passing a balloon catheter into the artery and expanding it at the site of blockage to locally dilate the vessel in that area.

Treatment of High Blood Pressure

Early diagnosis and treatment can control your blood pressure before it harms your health. You will have your blood pressure measured several times before your doctor will decide to prescribe any anti-hypertensive drugs. This is to make sure your blood pressure remains consistently high and is not just going up as a result of visiting the surgery. The aim of blood-pressure treatment is to reduce diastolic BP to below 85 mmHg and/or systolic BP to below 140 mmHg (thresholds may be different in some groups of people such as the very elderly). Sometimes two or even three different types of drug are needed to achieve this goal.

The aim of treatment is to lower your blood pressure gradually. Your doctor will start you off on a low dose of tablets to see how your blood pressure responds. If this is not enough, your dose may be increased, other drugs may be added in, or your medication may be completely changed. In some cases, more than one drug may be needed to achieve an acceptable BP. It may seem annoying to have to take one, two or even three different kinds of drugs when you feel perfectly well. But by prescribing treatment to keep your blood pressure within normal limits, your doctor is helping you to avoid the complications of uncontrolled hypertension – heart attack, stroke, peripheral vascular disease, kidney failure and even blindness.

It is important to take your blood pressure tablets regularly as prescribed. Some tablets only need only to be taken once a day, but others may need to be taken two or more times daily. This depends on how long each dose of medicine works in your body, and on how bad your blood pressure is.

When most forms of anti-hypertensive treatment are stopped, blood pressure only climbs up only slowly over several days or even weeks. With some forms of treatment, however, a rebound effect can occur so your blood pressure shoots back up.

Don’t stop taking your blood pressure treatment without first consulting your doctor. If you notice something that may be a side-effect, such as a rash, dizziness or sexual problems, always tell your doctor immediately so your dose can be altered or your treatment changed to one that suits you better.

Research shows that controlling hypertension can:

lower the risk of stroke by 35 per cent

reduce the risk of heart complications by 20 per cent

reduce overall risk of death at any age by 15 per cent.

GUIDELINES FOR DOCTORS

Doctors have been given guidelines to help them decide which patients with high blood pressure need treatment and which don’t. Basically, if your BP is consistently found to be above a certain level, it is important to bring it down to normal to reduce your risk of future complications such as coronary heart disease, kidney failure, eye problems (hypertensive retinopathy) or stroke. If complications (target organ damage) are already in evidence, the management of your condition will be stepped up.

These guidelines are based on extensive studies and trials that confirm the health benefits of treatment. In some cases, where blood pressure is borderline, and research does not show clear benefits of treatment, your doctor will monitor you regularly to make sure your BP does not go up. In these cases, diet and lifestyle changes are often enough to control your BP so you don’t need to take drug treatment at all.

You might find it interesting to read the guidelines given to doctors. These are as follows:

Measurement

Baseline BP is established by taking two to three BP readings per visit (while the patient is sitting) on up to four occasions.

Aims of Treatment

To reduce diastolic BP to less than 85 mmHg and to reduce systolic BP to less than 140 mmHg, but the optimal target in people with diabetes or kidney disease is lower. In the elderly, the threshold for treatment is usually higher, as research only shows consistent benefits in treating a BP that is persistently raised to 160/90 or greater.

Target Organ Damage

This is defined as left ventricle of heart enlarged; angina; transient ischaemia attacks (TIAs); stroke; peripheral vascular disease; heart attack; kidney function impaired.

Where the initial blood pressure is systolic ≥ 220mmHg OR diastolic ≥ 120mmHg, treat immediately.

Where the initial blood pressure is systolic 200–219 mmHg OR diastolic 110–119 mmHg, confirm over one to two weeks then treat if these values are sustained.

Where the initial blood pressure is systolic 160–199 mmHg OR diastolic 100–109 mmHg, AND the patient has cardiovascular complications, end organ damage or diabetes (type I or II), confirm over three to four weeks then treat if these values are sustained.

Where the initial blood pressure is systolic 160–199 mmHg OR diastolic 100–109 mmHg, but the patient has NO cardiovascular complications, end organ damage or diabetes, advise lifestyle changes, reassess weekly initially and treat if these values are sustained on repeat measurements over four to twelve weeks.

Where the initial blood pressure is systolic 140–159 mmHg OR diastolic 90–99 mmHg, AND the patient has cardiovascular complications, end organ damage or diabetes, confirm within four to twelve weeks and treat if these values are sustained.

Where the initial blood pressure is systolic 140–159 mmHg OR diastolic 90–99 mmHg, but the patient has NO cardiovascular complications, end organ damage or diabetes, advise lifestyle changes, reassess monthly; if mild hypertension persists, treat if the risk of coronary heart disease is greater than or equal to 15 per cent over the next 10 years using the Joint British Societies Coronary Risk Prediction Charts (which give a predicted future CHD risk depending on age, gender, smoking status, systolic blood pressure, cholesterol levels and diabetic status).

DRUGS USED TO TREAT HYPERTENSION

At present, six classes of drug are available to lower high blood pressure:

thiazide diuretics

beta-blockers

alpha-blockers

calcium channel blockers

ACE inhibitors

angiotensin-II receptor antagonists.

If a single drug is not effective, other anti-hypertensive drugs may be added, usually at intervals of at least four weeks, until good control of BP is achieved. Where hypertension is relatively mild (systolic BP less than 160mmHg, and diastolic less than 100mmHg), drugs may be substituted rather than used together.

Thiazide Diuretics

Thiazide diuretics (e.g. bendrofluazide, hydrochlorothiazide) are generally used as a first-line treatment in the elderly, or are combined with other anti-hypertensive drugs (e.g. a beta-blocker or ACE inhibitor) to boost their action in younger patients.

They lower blood pressure by increasing loss of salts through the kidneys into the urine. This tends to draw fluid out of the circulation, causes mild dilation of small arteries and lowers arteriolar resistance. The diuretics act within an hour or two of being given and are usually taken in the morning so you do not have to get up at night to pass water. When you first start taking the tablets, you may notice that you have to pass water more frequently than usual for the first few days;, then this effect tends to disappear as dilation of the arterioles occurs. Only low doses of hiazide diuretic are needed to bring your diastolic BP down by around 5 mmHg – higher doses have no further effect on BP and are more likely to cause side effects such as salt imbalances.

They should not be used by people with diabetes or with sodium, potassium or calcium imbalances, severe kidney or liver problems, active gout or Addison’s disease.

Beta-blockers

The way beta-blockers lower blood pressure is not fully understood but is thought to result from a combination of actions in which they:

alter the way nerve signals cause some blood vessels to dilate or constrict

slow the heart rate to around 60 beats per minute

reduce the force of contraction of the heart

decrease the workload of the heart and cardiac output

lower secretion of a kidney hormone, renin

reduce sensitivity of blood pressure sensors (baroreceptors)

block stress hormone (adrenaline) receptors

have some effects on the brain.

In general, beta-blockers are used as a first-line treatment in young people with hypertension and in people who have coronary heart disease. Because they also affect receptors in the lungs, they should not be used in people with asthma as they may trigger an asthma attack. Beta-blockers have been shown to significantly reduce the risk of having a second heart attack and may prolong life in high-risk individuals.

Beta-blockers should not be withdrawn suddenly, but must be tailed off slowly so that rebound high blood pressure (or angina) does not occur.

Alpha-blockers

Alpha-blockers (e.g. doxazosin, indoramin, prazosin, terazosin) lower blood pressure by dilating both arteries and veins. They are particularly helpful for older males who have both high blood pressure and problems associated with benign enlargement of the prostate gland. They sometimes cause a rapid fall in blood pressure after the first dose so treatment should be started with caution – usually at night so that if low blood pressure does occur, this is after you have retired to bed.

If taking Indoramin, you should avoid alcohol as it boosts alcohol absorption.

Calcium Channel Blockers

Calcium channel blockers (e.g. diltiazem, felodipine, isradipine, lacidipine, nicardipine, nifedipine) work by:

blocking the transport of calcium ions through cell membranes

relaxing muscles in arterial walls and reducing arterial spasm

dilating peripheral veins to encourage pooling of blood

dilating peripheral veins to encourage pooling of blood

reducing the force of contraction of the heart.

Treatment must not be stopped suddenly, but should be tailed off slowly to prevent rebound angina. Verapamil is slightly different from the others in the way it works, and should not be used together with a beta-blocker.

ACE Inhibitors

ACE inhibitor drugs are so-named because they block formation of Angiotensin Converting Enzyme (ACE). This in turn prevents formation of a substance called angiotensin II – a powerful constrictor of blood vessels – leading to dilation of both small arteries and veins. This reduces total peripheral resistance and arterial blood pressure. ACE inhibitors also increase blood flow to the kidneys, so more fluid and sodium is lost as urine. They are usually considered for treating hypertension when thiazides diuretics or beta-blockers are contraindicated, not tolerated, or fail to control high blood pressure.

They can cause a sudden fall in BP on giving the first dose, especially in people who are taking diuretics or who are dehydrated. Where possible, diuretic treatment is therefore usually stopped a few days before ACE inhibitor treatment is started. For some, the first dose is best taken at night on retiring to bed. Kidney function and salt balance should be checked before treatment is started. ACE inhibitors may be less effective in people of Afro-Caribbean descent unless combined with a thiazide diuretic.

Angiotensin-II Receptor Antagonists

These drugs (e.g. losartan, valsartan, candesartan) are similar to the ACE inhibitors except that instead of inhibiting angiotensin-converting enzyme, they block angiotensin-II to produce similar effects. This dilates blood vessels, stimulates kidney function and may also have a direct action on the brain to reduce drinking and increase urine output. At present, they are mainly used in people who develop a persistent dry cough as a troublesome side-effect of the ACE inhibitors as these particular drugs do not produce this problem.

Other Drugs

Occasionally, drugs from the above groups may not be sufficient or suitable for treating an individual case of high blood pressure. Two other drugs are sometimes used: hydralazine or methyldopa.

Hydralazine is a vasodilator that lowers blood pressure by relaxing arteries and increasing their diameter. When used to treat hypertension, it is usually combined with a beta-blocker and thiazide diuretic to stop the heart rate and cardiac output from increasing and to avoid fluid retention. It may cause a very rapid drop in blood pressure.

Methyldopa used to be the most popular drug for treating high blood pressure, and may still be taken by elderly patients who started on it many years ago. It lowers blood pressure by acting on the brain to trigger nerve actions that reduce heart output, urine production and arteriolar constriction. Methyldopa is often used together with a diuretic. It may cause a rapid fall in blood pressure, especially in the elderly.

Your doctor may also suggest taking low-dose aspirin or taking drugs to lower blood cholesterol levels if necessary.

IS ANTI-HYPERTENSIVE TREATMENT FOR LIFE?

Once drug treatment is started for high blood pressure, it is often for life. However, if you don’t have any complications from your high blood pressure and you have managed to make diet and lifestyle changes that naturally bring your blood pressure down, it may be possible to reduce your tablet dose or to withdraw it altogether. However, you should never alter your medication or stop it suddenly yourself. If your doctor decides to withdraw your treatment, this is usually done slowly in a step-wise fashion to prevent a sudden rebound hypertension. You will be followed up closely over a long period of time, as, in some cases, BP starts to creep back up again after six months, a year or more.

IF YOU SHOULD FORGET TO TAKE YOUR MEDICATION

If you do forget to take your treatment occasionally, it is unlikely that you will come to any harm. If you forget your tablets on a regular basis, however, you may run into problems.

If your treatment is only a few hours late, take it as soon as you remember.

If you have missed one dose and your next one is already due, just take one dose – DON’T take an extra dose next time. Be especially careful not to miss any further doses.

If you forget to take your blood blood-pressure treatment for more than one or two days, contact your doctor for further advice.

Tips to Help You Remember to Take Your Medication

Try to take your blood-pressure treatment regularly, at the same time every day, so you get into a routine.

Write a note for yourself and stick it where you will easily see it.

Keep your tablets/capsules where you can remember them easily, such as with your toothpaste (but make sure they are out of the reach of children).

Keep your tablets in a special dispenser box marked with separate containers for different times of the day.

If you have a programmable alarm watch, set it for when your medicine is due.

If you live with someone else, ask them to help you remember.

Make sure you get your next prescription in plenty of time so you don’t run out.

If you are going away, take enough tablets with you to last the whole time.

DRUGS TO LOWER HIGH BLOOD CHOLESTEROL

The best way to reduce high cholesterol is through making dietary changes and increasing the amount of exercise you take. Doctors usually recommend a low- fat diet, using olive or rapeseed oil for cooking, eating oily fish, taking fish oil supplements and garlic powder tablets.

If dietary changes have failed, your doctor may prescribe a lipid-lowering drug. This would be in instances where total blood cholesterol is above 7.8 mmol/l and is mainly in the form of harmful LDL-cholesterol.

In some cases, raised cholesterol levels are due to hereditary difficulties with fat metabolism. In these instances, one or more drugs often have to be prescribed.

Resins

Resins (e.g. cholestyramine, colestipol) work by binding to bile acids and preventing their reabsorption in the gut. This interferes with regulatory messages feeding back to the liver, so that more cholesterol is broken down into bile acids and excreted from the body. These drugs can lower LDL-cholesterol levels by up to 25 per cent on top of that achieved through dietary changes. Unfortunately, they cause triglycerides – another type of dietary fat linked to heart disease – to rise by up to 5 per cent. They are mainly used when a statin cannot be taken (see below). Side-effects include constipation and, in long-term treatment, a lack of fat-soluble vitamins A, D, E and K.

Fibrates

Fibrates (e.g. bezafibrate, ciprofibrate, clofibrate, fenofibrate, gemfibrozil) work by lowering liver synthesis of cholesterol. They reduce total cholesterol by up to 25 per cent and triglycerides by up to 50 per cent. They also have a beneficial effect on types of cholesterol in the blood, raising HDL and lowering LDL cholesterol. Unfortunately, they can trigger muscle pain (myositis), especially in patients with kidney disease. Some encourage gallstones and inflammation of the gall bladder by increasing excretion of cholesterol into the bile. Other possible side-effects include fatigue, muscle cramps, dizziness, painful extremities, hair loss, blurred vision, impotence and, rarely, inability to feel sexual pleasure.

Statins

Statins (e.g. fluvastatin, pravastatin, simvastatin) work by inhibiting a liver enzyme and lowering cholesterol production in the liver. LDL-cholesterol can be reduced by up to 40 per cent, with a beneficial rise in HDL-cholesterol and a moderate reduction in triglycerides. Statins are very popular drugs as they significantly reduce the risk of heart disease and stroke. Side-effects include reversible muscle problems, non-cardiac chest pain, diarrhoea, constipation, sinusitis, insomnia, flatulence and fatigue. Side-effects may be reduced by taking co-enzyme Q10 supplements.

Nicotinic Acid Derivatives

These drugs (e.g. acipimox, nicofuranose, nicotinic acid) lower both triglycerides and cholesterol levels by inhibiting the breakdown of body fat stores and the inhibiting production of fats in the liver. LDL-cholesterol can be lowered by up to 20 per cent and HDL-cholesterol is increased. They are limited by their side-effects of dilating the blood vessels dilation, causing dizziness, headaches and flushing.

Marine Fish Oils

Marine omega-3-triglycerides are a natural product that reduces blood levels of cholesterol and harmful triglycerides by inhibiting their production in the liver. They make the blood less sticky and reduce the risk of arterial thrombosis. They have few side-effects apart from possible nausea (if too much is taken) and belching. If diabetic, monitor blood gluscose levels carefully when starting to take them.

Probucal

This drug is in a class of its own, and its precise mode of action is unknown. It seems to increase excretion of bile acids in the faeces, so that more cholesterol is broken down in the liver to replenish them. It can lower LDL-cholesterol by up to 10 per cent, but HDL-cholesterol is reduced as well. Triglycerides remain unchanged. Probucal also acts as an antioxidant. Possible side-effects include flatulence, diarrhoea, mild abdominal pain and, very rarely, abnormal heart rhythm.

Aspirin

Aspirin is a commonly used pain killer and anti-inflammatory drug that also has a powerful blood-thinning effect. It lowers the stickiness of platelet particles in the blood so that they are less likely to clump together and form unwanted clots. This effect occurs at only a quarter of the dose needed to relieve pain. Although there is not yet felt to be enough evidence to recommend that everyone takes preventive aspirin, people who may be advised to take a regular mini-dose of aspirin every day include those who have:

angina

had a heart attack

had a coronary artery by-pass graft or dilation (angioplasty)

had surgery for poor circulation in the limbs

diabetes

several major risk factors for CHD.

Studies show that taking low-dose aspirin (75mg–150 mg) per day can reduce the risk of a heart attack or stroke by 30 per cent, and the risk of dying from them by 15 per cent (see Chapter 3).

If you fall into any of the above groups and are not taking a junior aspirin per day, check with your doctor that it will suit you and fit in with any other medication that you are taking.

PART TWO High Blood Pressure and Diet

CHAPTER 3 Atherosclerosis, Cholesterol and Dietary Fats

People with hypertension need to pay particular attention to the fats in their diet. By eating more of certain beneficial fats and less of potentially harmful ones, you can reduce your risk of future complications such as atherosclerosis.

Atherosclerosis

Atherosclerosis is the medical term for hardening, furring up and narrowing of the arteries. This process starts early in life, usually in the teens, and is triggered by normal wear-and-tear damage to your artery walls. Once the damage occurs, small cell fragments in the bloodstream – known as platelets – stick to the damaged area and form a tiny clot. These platelets release chemical signals to stimulate healing of the damaged area. Under normal circumstances, this would lead to healing, but if excessive damage continues – as a result of high blood pressure, raised cholesterol levels, poorly controlled diabetes or lack of antioxidants in the diet – the damaged area becomes infiltrated with a porridge-like substance that builds up to form a fatty plaque known as atheroma.

At the same time as the fatty plaques are developing, the underlying middle layer of the artery wall is affected and starts to degenerate, become fibrous and less compliant. Whereas the walls of healthy arteries are elastic and help to even out the surges of blood pressure produced every time the heart beats, the walls of arteries that have started to harden become more rigid. As a result, blood-pressure surges caused by the heartbeat are not evened out, and systolic blood pressure shoots up higher when the heart contracts. A vicious cycle then sets up, for just as atherosclerosis leads to high blood pressure, untreated hypertension can also lead to atherosclerosis by damaging artery linings and hastening the hardening and furring-up process.

If atherosclerosis is widespread throughout the body, it narrows the circulation so the diastolic BP – the pressure in the system when the heart is resting between beats – also becomes raised. Atherosclerosis can therefore raise both diastolic and systolic blood pressure. If left untreated, the raised BP in turn causes damage to the arterial system, hastening the development of atherosclerotic plaques and causing blood pressure to 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.

Конец ознакомительного фрагмента.

Текст предоставлен ООО «ЛитРес».

Прочитайте эту книгу целиком, купив полную легальную версию на ЛитРес.

Безопасно оплатить книгу можно банковской картой Visa, MasterCard, Maestro, со счета мобильного телефона, с платежного терминала, в салоне МТС или Связной, через PayPal, WebMoney, Яндекс.Деньги, QIWI Кошелек, бонусными картами или другим удобным Вам способом.