Good and Bad Cholesterol
Illustration of a lipoprotein
Cholesterol is a sterol, which is a type of lipid. Everybody has heard of good cholesterol and bad cholesterol, and some people are familiar with LDL and HDL, but very few people have heard the term lipoprotein. LDL and HDL are NOT cholesterol, they are lipoproteins which carry cholesterol.
Even though LDL and HDL are not cholesterol, it is still popular to refer to them as the good cholesterol (HDL) and the bad cholesterol (LDL).
We don’t find foods that are high in HDL and low in LDL. When we refer to dietary cholesterol, the cholesterol we consume, we are talking about just cholesterol, not LDL or HDL.
When people say “I have high cholesterol,” they are usually referring to a high total cholesterol. But it is possible that LDL is high and HDL is low, giving a normal total cholesterol reading, but a much more unhealthy cholesterol profile.
- Low-density lipoproteins (LDL)
- Transport cholesterol and lipids to body tissues
- Transport cholesterol and lipids to body tissues
- High-density lipoproteins (HDL)
- Scavenges cholesterol, brings it back to the liver
Even though LDL and HDL are not cholesterol, it is still popular to refer to them as the good cholesterol (HDL) and the bad cholesterol (LDL).
We don’t find foods that are high in HDL and low in LDL. When we refer to dietary cholesterol, the cholesterol we consume, we are talking about just cholesterol, not LDL or HDL.
When people say “I have high cholesterol,” they are usually referring to a high total cholesterol. But it is possible that LDL is high and HDL is low, giving a normal total cholesterol reading, but a much more unhealthy cholesterol profile.
Lipoprotein Video
Food Cholesterol vs Blood Cholesterol
It's important to differentiate between cholesterol in food (dietary cholesterol) and cholesterol in the blood stream, called blood cholesterol.
When we refer to blood cholesterol, we are talking about measurements of LDL, HDL and triglycerides (TG). Total cholesterol is not as important as LDL and HDL and TGs. High LDL and TG and low HDL will increase the risk of heart disease. The medical term for this is dyslipidemia.
Most people think that to decrease your blood cholesterol, you should limit cholesterol intake from foods. In general, this is not the case. Saturated fat and trans fat raise LDL and total cholesterol levels more than dietary cholesterol. Some people are hyper-responders, meaning that their body WILL respond to cholesterol in their diet, by increasing the LDL and total cholesterol. This is not common.
Refined carbohydrates can lower HDL and increase LDL. Exercise and polyunsaturated fatty acids can increase HDL in some people.
- Dietary cholesterol: cholesterol in the diet from food.
- Blood cholesterol: refers to total cholesterol level in the blood
When we refer to blood cholesterol, we are talking about measurements of LDL, HDL and triglycerides (TG). Total cholesterol is not as important as LDL and HDL and TGs. High LDL and TG and low HDL will increase the risk of heart disease. The medical term for this is dyslipidemia.
- Low LDL - less chance of fatal heart attack (below 130mg/dL)
- High HDL - lowers risk of heart disease (above 40mg/dL)
Most people think that to decrease your blood cholesterol, you should limit cholesterol intake from foods. In general, this is not the case. Saturated fat and trans fat raise LDL and total cholesterol levels more than dietary cholesterol. Some people are hyper-responders, meaning that their body WILL respond to cholesterol in their diet, by increasing the LDL and total cholesterol. This is not common.
Refined carbohydrates can lower HDL and increase LDL. Exercise and polyunsaturated fatty acids can increase HDL in some people.
Small Dense and Large Bouyant LDL
Smaller, denser LDL is associated with a greater risk of heart disease (more atherogenic). More recent research points to refined carbohydrates raising the smaller, denser LDL. Larger, buoyant LDL is still associated with increased heart disease risk, but to a much lesser extent (less atherogenic).
Refined carbohydrates / simple carbohydrates (white rice, white bread, pasta, cereal, processed and packaged foods such as crackers) will raise triglyceride levels more than fat or cholesterol intake.
There is actually quite a bit of genetic variability determining the lifestyle factors affecting HDL and LDL. We'll see new research in this area in years to come.
Refined carbohydrates / simple carbohydrates (white rice, white bread, pasta, cereal, processed and packaged foods such as crackers) will raise triglyceride levels more than fat or cholesterol intake.
There is actually quite a bit of genetic variability determining the lifestyle factors affecting HDL and LDL. We'll see new research in this area in years to come.
References
- Lamarche B, Lemieux I. Despres JP. The small, dense LDL phenotype and the risk of coronary heart disease: epidemiology, pathophysiology and therapeutic aspects. Diabetes & Metabolism Vol 25, 1999.
- Sizer, F. Whitney E. The Lipids: Fats, Oils, Phospholipids and Sterols. In: Nutrition Concepts and Controversies. 13 ed. Belmont, CA: Wadsworth. 2014.
- Krauss, RM, et al. Separate effects of reduced carbohydrate intake and weight loss on atherogenic dyslipidemia. Am J Clin Nutr May 2006. vol. 83 no. 5 1025-1031
- Lipoprotein illustration by OpenStaxCollege on Wikipedia, CC BY 3.0.
- Types of LDL by Christine Dobrowolski using an image by Zvaxquez on Wikipedia, CC BY-SA 3.0.
Last updated April 9, 2016