Book menuCHOLESTEROL - Full extract 

Over the years the subject of cholesterol has prompted a great deal of discussion. There now no doubt at all that a high blood cholesterol level is a significant risk factor for coronary artery disease. However, the blood cholesterol level should be considered along with the other coronary risk factors, like smoking, high blood pressure, obesity and a family history of coronary artery disease. 

Cholesterol is a white, waxy substance that is produced by animals and is present in foods like brains, egg yolks and meats like kidney and pate. Most people take in about 1 gram of cholesterol every day. The body also makes its own cholesterol; it forms an important part of cell structure and is necessary for the production of various hormones. 

Triglyceride is the other main type of fat. It is found in both animal and plant foods, and we take in about 100 grams each day. The bulk of the animal fat in our diet is in the form of triglycerides. Despite this, people still talk about the amount of cholesterol in our diet as if it is a big issue. Our main concern is the total intake of animal fat. 

The fat in our diet is an entirely different matter to the level of the fats in the blood. The blood cholesterol level is more important than the triglyceride level when it comes to the risk of coronary artery disease. However, after many years of looking like an innocent bystander, an elevated triglyceride level is now considered to be an additional risk factor. 

As well as the levels of total cholesterol and triglycerides in our blood, we can also measure the levels of individual lipoproteins, the substances that bind and transport the fats. The main types are LDL (low density lipoprotein), HDL (high density liporotein) and VLDL (very low density lipoprotein).

  • LDL carries most of the cholesterol in the bloodstream. If the level gets too high, the cholesterol gets deposited in the walls of arteries and causes them to become narrowed. It is better if the LDL cholesterol level is low. 
  • HDL is actually a cholesterol mopping-up lipoprotein. The  cholesterol bound to HDL does not get deposited in the arteries. A high level of HDL cholesterol is considered to be protective. 
  • VLDL transports mainly the triglycerides in the blood. High levels of VLDL may increase the risk of heart disease in some people. 

The ratios of total cholesterol to HDL, and LDL cholesterol to HDL may also be used as a guide to the risk of coronary artery disease. 

In patients who have an elevated total cholesterol level, it is somewhat reassuring if the HDL cholesterol is elevated. On the other hand, high total cholesterol and LDL cholesterol levels are associated with a higher incidence of coronary artery disease and heart attacks. A total blood cholesterol level less than 5.5 mmol/litre is regarded as normal. Lower levels are even better; the risk of coronary artery disease is possibly reduced even further. 

People with moderately elevated levels such as 7 mmol/litre require dietary advice to get the level down. This may take several months to achieve. If the blood cholesterol level remains high, it may be necessary to consider medication. The presence of other risk factors such as high blood pressure, vascular disease, diabetes or a family history of coronary artery disease all influence the decision on how actively the cholesterol level should be treated. More significantly, if the person has a past history of coronary artery disease and already had a procedure like coronary bypass surgery, lowering the blood cholesterol level becomes an even higher priority and medication should be started earlier. More recent research has shown that lowering the blood cholesterol level in these patients markedly improves their life expectancy. 

Several medications are available to help reduce a high cholesterol level. They are usually very well tolerated and very effective. Occasional blood tests are usually advised ... to check the cholesterol level and see that the medication is not causing any unwanted side-effects.

Losing excess weight and making dietary changes are the initial ways to reduce the blood cholesterol level. Many people can achieve a satisfactory reduction with dietary changes alone. The best approach is to lower the total fat intake, in particular the amount of saturated animal fats, by steering clear of fatty meats and full cream dairy products and keeping takeaway foods and desserts to a minimum. It helps to avoid foods such as butter, and to try monounsaturated olive oil for cooking. Interestingly, the latest margarine products containing vegetable sterols have been shown to bring about a modest reduction in blood cholesterol levels in their own right.

And life doesn't have to be boring. Increase the variety of foods in the diet and put more emphasis on fruit, vegetables and grain foods. Having more dietary fibre can also help, especially with foods such as oatbran. It is a good idea to replace meat with fish once or twice a week. As well as being low in overall fat content, some fish contain omega 3 fatty acids which lower triglyceride levels, and reduce the risk of coronary artery disease by other means as well. 

Occasionally, blood tests show that an underlying illness such as diabetes or an underactive thyroid gland is contributing to the elevation of the cholesterol level. And sometimes there is an inherited cholesterol or triglyceride problem that runs in a family. A very high cholesterol or triglyceride level and a strong family history of early heart disease is a good prompt to get other family members to have their cholesterol levels checked. 

We need to keep the blood cholesterol level in the context of other risk factors for coronary artery disease, such as smoking, high blood pressure, being overweight and lack of exercise. It makes sense to keep our blood cholesterol level in the normal range. But every effort has to be made to reduce the other risk factors as well. 

Health Tips:
* Excellent booklets on low-fat diets and cholesterol can be obtained from the National Heart Foundation¹.

* If your blood cholesterol level is elevated, ask your doctor for advise about how it can be reduced.

Web links:
 ¹ www.heartfoundation.com.au


 Dr. Andrew Pattison: Common Consultations
North East Valley Division General Practice, Melbourne, Australia.   Disclaimer
  - Last modified: August 18, 2001