Cholesterol Control – How can you keep cholesterol in check?
By Dr Paul Chiam
Published on Ezyhealth on March 2015
Cholesterol is important for our body functions but could also cause problems if there are high levels in our blood. The fat that we eat gets changed by the liver into cholesterol and triglycerides. Since cholesterol is made in the liver, it is only found in animal products and not in vegetables.
The Good and the Bad
The cholesterol and triglycerides are packaged into lipoproteins for transport through the bloodstream.
The two types of lipoproteins we are concerned about are:
- Low density lipoprotein (LDL)
- High density lipoprotein (HDL)
LDL is also known as the “bad” cholesterol because it gets deposited in the blood vessel walls. This is called atherosclerosis and leads to blood vessel narrowing and can result in heart attacks and strokes. HDL is also known as the “good” cholesterol as it brings the bad cholesterol back to the liver.
The High and the Low
To measure your cholesterol levels, you can take a fasting blood sample for lipid profile. You will need to fast for at least eight hours before the test. The numbers usually measured are:
- Total cholesterol
- Triglycerides (TG)
Of these, LDL is considered the most important parameter.
- Patients with established heart disease, previous stroke, peripheral artery disease or diabetes should aim for an LDL level lower than 2.6mmol/L (100mg/dL) or even less than 1.8mmol/L (70mg/dL).
- For people with no cardiac risk factors, an LDL level less than 3.4mmol/L (130mg/dL) would be the target.
- An LDL level above 4.0mmol/L (160mg/dL) is considered high.
- HDL should be at least 1.0mmol/L (40mg/dL) and ideally above 1.5mmol/L (60mg/dL). Simply put, the lower the LDL, the better; and the higher the HDL, the better.
- The target for TG is less than 1.8mmol/L (150mg/dL) and a level of over 2.3mmol/L (200mg/dL) is considered high.
Why are these numbers important?
Reducing LDL decreases cardiovascular adverse events (heart attacks, strokes) and overall cause of death. The lower the LDL, the greater the risk reduction.
Similarly, people with high HDL levels seem to be at lower risk of cardiovascular events.
Although high TG levels are associated with increased cardiovascular events, the main concern with very elevated TG levels (> 5.0mmol/L or 450mg/dL) is the risk of pancreatitis, an inflammation of the pancreas that can be potentially fatal. Reducing TG levels can reduce the risk of cardiovascular events.
Causes of High Cholesterol
The commonest reason for elevated cholesterol levels is dietary (eating food with high saturated fat and cholesterol content). Animal fat is saturated fat and is solid at room temperature, whereas fats that are liquid at room temperature (such as olive oil, canola oil, safflower oil, soybean oil, corn oil) are unsaturated (polyunsaturated or monounsaturated) fats. Eating saturated fat increases LDL and eating unsaturated fat actually lowers LDL and raises HDL.
Trans fats (found in cookies, crackers, potato chips, margarine etc) are particularly bad as they raise LDL and lower HDL. Thus, consuming foods with trans fats is even worse than consuming foods with the same amount of saturated fat.
High cholesterol tends to run in families. Other conditions that can lead to high cholesterol levels are diabetes (lowers HDL and raises LDL), a lack of thyroid hormone, obesity and rare genetic diseases.
Treatments for High Cholesterol
The first step is to get one’s cholesterol levels checked. You should perform a cholesterol profile as early as at age 20, and get re-tested every five years. More frequent testing (every one to two years) may be required if your levels are not desirable.
Diet and Exercise
Patients with high cholesterol should first try dietary modification and exercise for three to six months.
Cut down on foods high in saturated fat and cholesterol. No more than 30% of your total daily calories should be from fat, no more than 8% to 10% from saturated fat, and total cholesterol intake should be less than 300mg per day.
Incorporate greater proportions of green leafy vegetables and fruits (high fibre diet), fish and white meat (instead of red meat) in your diet. Choose whole-grain breads, whole- wheat pasta, brown rice, oatmeal and oat bran.
Moderate amounts of alcohol may increase the level of HDL. However, be careful not to over-indulge. Alcohol also increases caloric intake.
Moderate intensity aerobic exercises reduce LDL and raise HDL levels and can help lower blood pressure.
Diet and exercise can achieve about 10% to 15% LDL reduction and 5% to 10% HDL increase in most patients. For most people with high cholesterol levels, drug therapy would also be required.
As LDL is the main target of treatment, most treatment drugs primarily reduce LDL. Other drugs mainly reduce TG or raise HDL.
Statins (e.g. Zocor, Lipitor, Crestor) lower LDL levels by decreasing liver production of LDL. They are generally well tolerated and safe. Other classes of drugs (e.g. Ezetimibe, a cholesterol absorption inhibitor) may be added on if the LDL level is still high despite high doses of the statin.
Alternative drugs may be considered for rare patients who cannot tolerate statins. A repeat fasting cholesterol level test is usually performed after six to 12 weeks and the liver function is also checked (as the drug can cause liver enzyme levels to be raised). In rare cases where the liver enzyme is very elevated, the drug has to be stopped.
Fibrates are used for patients with very high TG levels. Fibrates reduce liver production of very low density lipoprotein (VLDL) which contains mainly TGs, and increase removal of TGs from the blood. A repeat cholesterol level and liver function test should be done after six to 12 weeks.
A combination of a statin and fibrate may be combined cautiously as there is a higher risk of severe side effects. One rare but serious side effect of statins or fibrates is muscle breakdown. Patients who experience severe muscle ache/ pain while on cholesterol medications should inform their physician promptly.
Omega-3 fatty acid supplement lowers TGs. Omega-3 oils do not have significant effects on LDL or HDL levels.
High cholesterol levels (especially LDL) can cause blood vessels to narrow and lead to heart attacks or strokes. Regular cholesterol tests are recommended and a high cholesterol level can be treated with a combination of dietary modification, exercise and drug therapy.