HDL and LDL Cholesterol

On the garlic and cholesterol page I mentioned HDL and LDL cholesterol. On this page I'll give a simple overview of the difference. Please note that I'm not a doctor!

Cholesterol is a white, waxy substance found in the blood plasma. It is essential to life. However overly high cholesterol levels can have serious health implications on the cardiovascular system in particular leading to atherosclerosis. Excessive cholesterol levels can be an indicator of increased risk of heart attack and/or stroke.

Once upon a time things were simple. Cholesterol was cholesterol and everyone "knew" that too much of it was a bad thing.

Nowadays doctors realise that the situation is more complex than that. Cholesterol comes in several forms, the most common of which are high-density lipoproteins (HDLs) and low-density lioproteins (LDLs). Of these, HDLs are known as "good" cholesterol whilst LDLs are "bad". That, of course, is a simplification but a good starting point.

2005 UK recommendations (from the Joint British Societies - JBS2) are total cholesterol below 4.0mmol/l, "bad" cholesterol below 2.0mmol/l (1). Obviously these are general guidelines which may not be appropriate for everyone.

LDL Cholesterol

LDL stands for low-density lipoproteins. These are often referred to as bad cholesterol.

Low density lipoproteins don't move around the bloodstream very well. They tend to get "left behind" and can clog up the arteries. Such clogging can contribute to atherosclerosis. If a blood clot occurs in a blocked region then it can result in heart attack and/or stroke.

High LDL levels are often associated with a high level of triglyceride, a fat which is found in food.

HDL Cholesterol

HDL stands for high-density lipoproteins. These are often referred to as good cholesterol.

Unlike LDLs, HDLs can be carried around the bloodstream much more easily. As such they don't contribute to dangerous hardening of the arteries. In fact many experts believe that HDL cholestrol can actually help to remove LDLs and other substances that are blocking the arteries.


Measuring total cholesterol level is of limited use. It's important to distinguish between HDL and LDL - very often this is expressed as the HDL/LDL ratio. Unfortunately not all of the home cholesterol tests you can buy make this distinction. All individuals differ, so contact your doctor to get your cholesterol checked properly.


(1): Your Cholesterol Number