Prof Sim Kui Hian: The definition of a "healthy" level of cholesterol has been repeatedly adjusted during the past 30 years.
Cholesterol can be both good and bad as our individual biochemistry allows for a wide range of cholesterol levels.
However, not many know that what is more important than total cholesterol is your relative quantities of HDL (good) cholesterol in comparison to LDL (bad) cholesterol.
Essentially, you need to ensure that your HDL cholesterol levels stay high, and your LDL cholesterol levels stay low, relative to each other.
Dr Khoo Kah Lin: LDL cholesterol is a major risk factor for heart disease. As such, it is the main focus of cholesterol-lowering treatment.
Your target LDL number can vary, depending on your underlying risk of heart disease.
Most people should aim for an LDL level below 3.4 mmol/L (130 mg/dL).
If you have other risk factors for heart disease, your target LDL may be below 2.6 mmol/L (100 mg/dL).
If you're at very high risk of heart disease, you may need to aim for an LDL level below 1.8 mmol/L (70 mg/dL). In general, the lower your LDL cholesterol level is, the better.
We have National Cholesterol Education, or NCEP, guidelines for where your HDL should be.
What we look for in the HDL guidelines - and these are from the American Heart Association and the American College of Cardiology - is for men to have HDL above 40, and for women, it should be above 50.
Studies have shown that for every 1 per cent that you raise your HDL cholesterol, there's a 2-3 per cent reduction in cardiovascular risk for heart attacks and strokes.
Say a 50-year-old man's HDL is 36. We get it up to 40, which is about a 10 per cent increase. That would translate to a 20 per cent reduction in risk.