We have all heard of Cholesterol. We are bombarded with advertising warning us of the dangers associated with an elevated blood Cholesterol and the importance of lowering our Cholesterol. Many foods have labels advertising Low or No cholesterol content.The terms Light or Extra light are used on packaging to persuade us to buy a particular brand when often they have nothing to do with cholesterol levels. No doubt your Doctor has advised you to have your cholesterol checked. But what exactly is it ?
What is Cholesterol ?
Cholesterol is a white fatty substance found in our blood. It is a naturally occuring fat in humans and other animals. The liver produces about 1 gram of cholesterol per day, which is all the body requires. The body needs cholesterol to make certain hormones , vitamin D , bile acids, cell membranes and nerve sheaths. Bile acids are essential for digestion and absorption of fats from our intestines.
Question:- Well then, if Cholesterol is necessary for many normal bodily functions, why is it a problem?
Answer:- The answer lies in both the type and quantity of cholesterol in the blood.
Researchers at Framingham near Boston in the USA were among the first to show the relationship between elevated levels of cholesterol and heart disease. Other researchers in California in the USA found that there were different types of cholesterol which had different functions
How does Cholesterol function in our body?
Cholesterol in the body rarely exists as pure cholesterol, because it is not soluble in water -and therefore blood. Instead cholesterol molecules attach themselves to certain types of tiny transport proteins called Lipoproteins.
Two main types of lipoproteins are the carriers of cholesterol and will be the ones we discuss:-
(1) Low Density lipoproteins ( LDL ) carry about two thirds , while most of the remainder is attached to
(2) High Density Lipoprotein ( HDL )
1. Low Density Lipoproteins ( LDL ):- LDL transports cholesterol to the tissues. The problem arises when there is damage to the inner layer of the wall of an artery particularly in the heart or brain. The earliest sign of damage to an artery is the appearance of “fatty streaks”. These are yellow patches on the inner wall of the artery which are stuffed with cholesterol. These plaques can increase in size and gradually lead to blockage of arteries, a condition called atherosclerosis. If this occurs in the heart blood vessels, a heart attack ( coronary occlusion) occurs or if in the brain , a stroke. LDL is often referred to as ” BAD cholesterol”
The discovery of the relationship between LDL cholesterol and heart disease was made byDr Joseph Goldstein and his colleague Dr Michael Brown at the Texas Health Science Centre in Dallas USA in the 1970′s. They discovered that human cells have LDL receptors which remove cholesterol from the blood stream. The lack of these receptors is the cause of familial hypercholesterolaemia, a severe form of high cholesterol which leads to the development of heart disease at any early age. Their finding led to the development of the Statin Drugs which are commonly used today in the management of high cholesterol.
They received The Nobel Prize in 1985 for their work.
2. High Density Lipoprotein (HDL):- HDL on the other hand is referred to as GOOD cholesterol. It helps to clear the arteries by removing cholesterol from the artery wall and other tissues and carrying it to the liver to be converted to other substances or removed from the body through the bile.
Investigations have shown that this reverse transport mechanism has a protective effect and therefore reduces the risk of heart disease.
Recent studies have also shown that HDL has other important functions. It has Anti-oxidant and anti-inflammatory properties which help protect the lining of the blood vessels.
If the lining of the blood vessels are damaged, the cells produce a sticky substance .Certain cells from the blood can adhere to the damaged cell wall, so leading to the development of plaque and consequently atherosclerosis. It appears that HDL can inhibit the secretion of the “sticky” substance and so reduce inflammation.
Factors causing an increase in LDL:-
1. Genetic Factors such as Familial Hyperlipidaemia
2. Diet: Ingestion of foods high in Cholesterol, increased intake of foods containing saturated ( animal ) fats and foods containg Trans Fats
3. Alcohol excess, may increase the production of another low density lipoprotein called VLDL. This leads to a high cholesterol level and the collection of another type of fat called Triglyceride.
4. Impaired Liver function as a result of alcohol excess , or Illicit drug use leading to hepatits B and C
7. Hormone imbalance, such as an under-functioning Thyroid (Hypothyroidism)
8. Pregnancy and Breast Feeding: Hormone changes which occur during pregnancy and breast feeding may lead to abnormally high cholesterol and Triclyceride levels. Therefore the lady’s diet needs to be monitored carefully by her doctor, while bearing in mind the need for adequate supplies of nutrients and energy.
9. Post menopausal women are at higher risk of developing high cholesterol levels and therefore heart disease. This is a result of the falling oestrogen levels due to gradually declining function of the ovaries. Oestrogen has some protective effect on the wall of arteries.
10. Chronic kidney disease
11. Certain Medications, such as , the Contraceptive Pill, and thiazide diuretics, those used to treat fluid retention and high blood pressure
Factors contributing to a fall in HDL:-
1. Genetic Factors - certain rare diseases
2. Cigarette smoking.
3. Lack of Physical exercise
5. Male Hormones - Testosterone excess in women with a condition called Polycystic Ovary Disease
Conclusion: So we have discussed ” What is Cholesterol ” , we have found that there are different types of Cholesterol and learned a little of the way they function.
We now know that HDL cholesterol is Good and has a protective effect in our body and the level needs to be high.
We see that the villain is LDL cholesterol and a low HDL. We have discussed the many reasons why the level of LDL may be high.
I would recommend that you investigate the producy ” Cholesterol Support ” by clicking on the Dr Sears banner below.
In Part 2, I will discuss that other Fat, Triglyceride and what we can do to solve the problems of the condition called Hyperlipidaemia.