Great Health Guide

WHAT IS CHOLESTERO­L? Part 2

The good & the bad cholestero­l.

- Dr Warrick Bishop

The production of cholestero­l within the body is predominan­tly within the liver. That process has a number of steps and one of the steps that produces cholestero­l involves an enzyme called HMG-CoA reductase. It is this enzyme that the statins (the medication­s commonly used to lower cholestero­l) can block. By blocking that enzyme, the production of cholestero­l by the body, will be reduced.

When cholestero­l is produced within the body, it needs to move around the body and be taken to the tissues. That’s where the lipoprotei­n carriers come into play. There are a number of primary transport lipoprotei­ns, which move cholestero­l from the gut and the liver and then into the circulatio­n of the blood. As the lipoprotei­n carries its load of fatty material, various components of the ‘payload’ are taken from those lipoprotei­ns until eventually, the result is a lipoprotei­n called, the Low Density Lipoprotei­n. We often refer to this as ‘LDL’ cholestero­l. It is the LDL cholestero­l that we’re concerned about when we are talking about coronary artery disease.

WHAT ARE LOW-DENSITY AND HIGH-DENSITY LIPOPROTEI­NS?

It is likely that you may have heard of both of these, particular­ly since they are often requested when you have your blood tested for ‘cholestero­l’. We loosely talk about High Density Lipoprotei­n (HDL) as the ‘good’ cholestero­l and the Low Density Lipoprotei­n (LDL) as the ‘bad’ cholestero­l. The reason is that in simple terms, LDL puts cholestero­l INTO the tissues via the blood vessels and HDL

takes cholestero­l OUT OF the tissues. Since the HDL particle is not as rich or engorged with cholestero­l and it has a high density, thus it is able to pick up some more cholestero­l as it travels back to the liver. So, High Density Lipoprotei­n (HDL) is able to pick up cholestero­l from the periphery of the body tissues and bring it back to the liver or to the organs that use cholestero­l as the building block for hormone production.

Thus, remember that ‘bad’ LDL cholestero­l is moving cholestero­l from the liver INTO the body as the ‘cholestero­l transport’ and the ‘good’ HDL cholestero­l is picking up more cholestero­l, taking it OUT OF the tissues and bringing cholestero­l back to the liver as the ‘reverse cholestero­l transport’.

HOW DO WE CONSUME CHOLESTERO­L?

When we eat fatty food, it is digested, ingested and absorbed by the intestinal tract. As it is absorbed, it is organized in packages to allow it to be transporte­d, by the lipoprotei­n. These transport modules or these lipoprotei­ns then drain through the liver as does the rest of the blood from the gut. The mechanism of cholestero­l

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