Serum Cholesterol Basics

In response to my post linking Dr. Davis' interview about arterial plaque, Melinda asked:

"Are the "small LDL" cholesterol particles the same as VLDL?"

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Here are some basics:

• VLDL: Very Low Density Lipoprotein
  
• IDL: Intermediate Density Lipoprotein
  
• LDL: Low Density Lipoprotein
  
• HDL: High Density Lipoprotein

VLDL is not the same as the pro-atherosclerotic small, dense LDL. But, by itself, VLDL is also a risk factor for atherosclerosis.

Some Facts About VLDL

• VLDL is generally larger in size than LDL, and less dense (more fatty).
  
• VLDL is triglyceride-rich.
  
• VLDL + LDL + HDL = Total Cholesterol. (Assuming the lab includes IDL in the LDL figure. Lp(a) is also included in the LDL figure.)
  
• VLDL is converted to IDL, and then to LDL, in the bloodstream. (VLDL --> IDL --> LDL)

Why is Small, Dense LDL a Problem?

Small, dense (protein-rich) LDL is more of a problem than larger, less dense (fat-rich) LDL because the small variety:

• Doesn't get cleared as quickly from the bloodstream as larger LDL. (Larger LDL fits the LDL-receptor better.)
  
• Tends to stick more easily to the artery wall.
  
• Is more susceptible to oxidation. The oxidation of LDL is one of the larger contributors to the development of a fatty streak.

Relationship Between VLDL and Small LDL

One relationship between all these types of fats:

• When your triglycerides are low, your VLDLs contain less triglyceride and are smaller. They tend to convert to larger LDL in the bloodstream.
  
  
• When your triglycerides are high, your VLDLs contain more triglyceride and are larger. They tend to convert to smaller LDL in the bloodstream.

Lowering Small LDL

One goal then to lower levels of small, dense LDL is to lower triglycerides. This can be accomplished by:

• Weight loss.
  
• Lowering the glucose load (eating fewer refined carbohydrates and sugars), although this effect may not have as great a long-term effect as weight loss.
  
• Consuming omega-3 fatty acids, especially EPA and DHA (found in fish oil), which have been shown to sharply reduce levels of triglycerides.
  
• Taking niacin (nicotinic acid).
  
• Taking fibrates (a unique mechanism of action that I hope to write about later).
  
• Increasing physical activity.

All of the above, except for fish oil, also tend to increase HDL, which is good.
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