What are lipids?
Lipid is medical terminology for fat. The most commonly occurring lipids (fats) in the circulating blood are fatty acids, cholesterol, triglycerides and phospholipids. Fats are an essential component of the body, used in the development of hormones and production of bile. They are a core component of the cells that make up different tissues in the body and act as an important energy store.
Fats including cholesterol and triglycerides are absorbed in the diet, but may also be produced by the body, in the liver and other tissues. Despite being very important, too much fat is associated with the development of cardiovascular disease and so the bodies mechanisms work hard to regulate levels. In certain people this process is less controlled than others, resulting in dyslipidaemia (abnormal fat levels), which may be worsened by increased amounts of fat absorbed through the diet. Unfortunately some people are predisposed to high levels of fats in the blood despite a very good diet and require medication to lower their risk of heart disease and strokes.
What are lipoproteins?
Fats do not dissolve in water and are bound to proteins to be transported around the body. Many of these fat protein combinations are known as lipoproteins. Lipoproteins are distinguished on the basis of their density, with some weighing more than others. Chylomicrons are the smallest, followed by very low density (VLDL), intermediate density (IDL), low density (LDL) and high density lipoproteins (HDL). Each of these lipoproteins (fatty proteins) are composed of different fats including cholesterol, triglycerides and fatty acids along with different types of protein. Low density lipoproteins (LDL) carry most of the cholesterol, which means they are responsible for depositing larger amounts of cholesterol in the walls of blood vessels. High density lipoproteins (HDL), bind cholesterol from cells and then exchange it for triglycerides, releasing cholesterol particles that can be taken up in the liver and excreted in bile. High density lipoproteins thus play a role in lowering total body cholesterol.
Is there good and bad cholesterol?
Over recent years much evidence has accumulated, particularly linking elevated levels of total cholesterol (TC) and low density lipoprotein cholesterol (LDL Cholesterol) with increased cardiovascular risk. High density lipoprotein cholesterol (HDL Cholesterol) however has a protective effect, so you do not want high levels of LDL and total cholesterol, but do want reasonable levels of HDL cholesterol.
What symptoms or signs would I have with high cholesterol?
One of the problems with dyslipidaemia, is that it is usually asymptomatic and so often only diagnosed through screening or if individuals present with an associated medical problem. Sometimes patients can develop clinical signs of dyslipidaemia, including xanthelasma (white / yellowish fatty deposits around the eyes) or xanthoma (fatty deposits often found on the elbows or tendons). The absence of these signs however does not indicate a normal cholesterol.
What options are available to me if my cholesterol if high?
A range of management options for dyslipidaemia exist, including lifestyle modifications, such as reduction in intake of dietary saturated fats, increase in dietary fibre, weight loss and exercise. Where cholesterol levels are higher and lifestyle modifications are unsuccessful, then a variety of different medication types are available. These work to reduce the bodies production of fats and increase excretion of fats from the body.
Should elevated cholesterol always be treated?
In short the answer is not always. Dyslipidaemia is not normally considered in isolation, but as one factor increasing overall risk. Where additional risk factors are present, then the doctor may pursue very tight control of fat levels in the blood. Those patients who have suffered a prior heart attack, or are known to have coronary artery disease, peripheral vascular disease, strokes, patients with diabetes or chronic kidney disease are automatically considered high risk and treated very actively. Other people may have a markedly elevated single risk factor such as very high blood pressure.
Some patients have extremely high cholesterol, that has a genetic basis running in families. In these situations the elevated cholesterol levels are treated actively irrespective of whether other risk factors are present. Where very high cholesterol is identified, there is often an indication to offer screening to immediate family members, to ensure that they do not require treatment.
Useful educational links
European Society of Cardiology and European Atherosclerosis Society: 2016 Guidelines for the management of dyslipdaemias
National Institute for Health and Care Excellence (NICE): 2014 Lipid modification – cardiovascular risk assessment and the modification of blood lipids for the primary and secondary prevention of cardiovascular disease
American College of Cardiology and American Heart Association: 2013 Guideline on the treatment of blood cholesterol to reduce atherosclerotic cardiovascular risk in adults.
British Heart Foundation: High Cholesterol