There are a number of fats in our blood. Doctors measure levels of some fats per unit of blood as part of a heart disease risk assessment. These are known as serum lipids, and the most common ones are discussed below, though there are many more subdivisions beyond the scope of this ebook.
Cholesterol is waxy fat, made naturally in our bodies by the liver, and is an essential part of living tissues. Too much cholesterol builds up on the walls of arteries including those which supply the heart (coronary arteries). If these deposits become too large clots are liable to form, cutting off blood flow through the vessel causing the tissues which are served by the vessels in question to have insufficient blood supply. This is the case in heart disease where the coronary arteries become blocked, or in a stroke where the cerebral arteries block.
A high cholesterol level can be inherited but it can also be significantly affected by lifestyle, especially exercise levels and diet. A raised blood cholesterol level is a primary risk factor for heart disease.
Your total cholesterol level can be divided into subfractions to give a more accurate reading of what is going on in your blood. The two main subfractions are:
• LDLs - Low density lipoproteins are 'bad' cholesterol, and this level should be kept to a minimum. The LDL level signifies fat which is being taken to peripheral tissues for storage, or to be laid down as cholesterol in blood vessel walls.
• HDLs - High density lipoproteins are 'good' cholesterol as it denotes cholesterol which is being returned to the liver for disposal. This level should be high, signifying a reduced risk of heart disease.
There are further subfractions that give an even more detailed reading of what is going on, but since doctors rarely measure them, I will not go into any more detail.
The problem with total cholesterol (TC) level is that it masks the subfractions. You could have a fairly high TC but this may be because HDLs are high, reducing heart disease risk. Nevertheless, if your TC is very high it is very likely that your LDLs are also raised.
Triglycerides are another fat in our blood. Doctors commonly measure this level, as a high figure also increases your risk of heart disease. Triglycerides are not only affected by the amount of fat in your diet, but also by exercise level, dietary sugar intake and alcohol consumption.
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