The aim of treatment is to lower your cholesterol levels and thereby minimise your risk of serious cardiovascular disease (CVD) and organ damage, which could be permanent (think heart attack, stroke or sudden death).
The best reduction of risk is by paying attention to all the risk factors. Cholesterol plays a role across the board but becomes the dominant driving force for vascular disease when the total cholesterol exceeds 7mmol/L or the LDL cholesterol exceeds 5mmol/L.
Very high-risk patients (those with genetic disorders, manifest vascular disease or diabetes) will need treatment with medication regardless of other considerations.
Those who have been identified as high risk by calculating their risk from multiple risk factors also need treatment. In most cases, you will be considered high risk if you have a higher than 20% risk of a heart attack, or a higher than 5% risk of death within 10 years.
1. Non-medical interventions
These include dealing with known risk factors and can consist of:
• Smoking cessation. Smoking is an independent major risk factor for CHD, cerebrovascular disease and atherosclerotic cardiovascular disease.
• Exercising more. This favourably influences the TC, raises HDL, lowers triglycerides and possibly lowers LDL; improves body mass and lessens the risk of diabetes.
• Losing weight. Obesity is associated with a number of risk factors for atherosclerosis, cardiovascular disease and cardiovascular mortality. These include hypertension, insulin resistance and glucose intolerance, hypertriglyceridaemia and reduced HDL-cholesterol. Typically LDL particles are remodelled to small particles as well.
• Eating correctly (quantity and quality). Except for the inherited genetic forms of hypercholesterolaemia, cholesterol production is closely linked to fat intake and metabolism. Just by controlling food intake, especially of fat, your total cholesterol can be lowered by 10-20%. The prudent diet advised here includes:
1. Eating enough kilojoules to reach and maintain your correct body weight, which is a BMI of 20-25 kg/m2.
2. Eating 55% or more of your total kilojoules (kJ) as complex carbohydrates.
3. Eating 12-15% of your total kilojoules as protein.
4. Eating generous amounts of fresh fruits, vegetables, grains, cereals, poultry, fish, lean meats and low-fat dairy products.
5. Limiting your total daily fat consumption to 30% or less of your total kilojoule intake.
6. Consuming less than 200mg cholesterol daily. Note that cholesterol is not an essential dietary component but accompanies animal products which provide protein, iron and vitamin B12.
7. Taking supplements. While a healthy lifestyle with a balanced diet can supply all the nutritional needs, some supplements have been shown to be of benefit. These include omega-3 oils, soy, sterol-enriched margarines, some forms of fibre, garlic, nuts, and antioxidants such as in green tea.
2. Medical interventions
• Identifying and treating known contributory conditions, such as diabetes, hypertension, thyroid disorders, kidney disease and several others.
• Medical treatment to lower your total cholesterol by targeting the particle that carries the bulk of the cholesterol.
As cholesterol is derived from two sources, there are two basic approaches to lowering total cholesterol: limiting the amount the body manufactures, and interrupting the recycling of used cholesterol. The best results are obtained when these two approaches are combined.
Drugs that limit the production of cholesterol
The statins are a group of drugs which interfere with the production of cholesterol in the liver. This results in the liver importing more from the blood and in the process lowering the level of cholesterol in your blood.
Statins are the most commonly used and most potent anti-cholesterol drugs, and can reduce your total cholesterol by 20 to 60%. They work by inhibiting one of the critical enzymes needed to produce cholesterol.
The effects of statins add to those of a controlled diet. Adverse reactions, such as muscle pain, occur in a minority of patients. Benefit has been shown in numerous studies.
For patients with severe hypercholesterolaemia, statins alone may not be enough – even at high doses. The lowest dose that achieves “target” levels and avoids side effects should be chosen.
Interestingly, most of the response to a statin is seen at the lower dose and thereafter every doubling of the dose of statin, results in only a further 6% reduction in cholesterol. In such cases, the addition of a different type of medication is advised.
Examples of statins include pravastatin, lovastatin, simvastatin, atorvastatin and rosuvastatin.
This group of drugs acts mainly to lower triglycerides and may help to raise HDL. They act on several genes to alter the metabolism of lipids in many tissues. This includes lowering the export of triglyceride from the liver, burning more of the fatty acids in the liver and raising the production of HDL.
Examples of fibrates are bezafibrate, gemfibrozil and fenofibrate.
This is one of the B group of vitamins. It can help normalise cholesterol levels when given in very large doses. Its use, however, is often limited by its unpleasant side effects, such as severe flushing and skin rashes; it can also bring on gout. Some more recent products claim to be flush-free but may not lower cholesterol effectively.
Nicotinamide is a different chemical form of nicotinic acid but is ineffective.
Drugs that interrupt the recycling of cholesterol
Bile acid sequestrants
The best known of these is cholestyramine but it is no longer available in South Africa. It binds to bile acids in the gut and so prevents reabsorption. As a result, the liver is stimulated into producing new bile. Because cholesterol is used in the production of bile, the total amount of cholesterol in the circulation is gradually reduced.
Side effects are common and include abdominal discomfort, constipation and possible vitamin deficiencies.
This drug prevents the absorption of cholesterol by the small intestine and so the cholesterol recycling process is disrupted. As a result there’s an increased clearance of cholesterol from the blood into the liver and a decrease in total cholesterol, LDL-cholesterol.
Side effects are uncommon and most patients tolerate the drug well.
At present, ezetimibe plus a statin is the most effective drug combination to drastically lower LDL cholesterol.
Caution: All of these medications must be used with care and under medical supervision. Most drugs may cause abnormalities in liver function, so liver function should be tested before the drugs are started and should monitored if it was abnormal or when there is a change in health.
There are also known drug interactions which can affect the results and side effects of cholesterol drugs, such as when they’re used with warfarin, certain herbs and other anti-cholesterol medication. Cholesterol drugs should not be used in pregnancy and while breast feeding is done.
Reviewed by Prof David Marais, FCP(SA), Head of Lipidology at Groote Schuur Hospital and the University of Cape Town. January 2018.