When is high LDL not "bad?" How does your doctor calculate your LDL? When is the 'standard formula' for LDL calculation not reliable? All this and more is answered in this very dense, very smart piece (see link below to protein power.com).
Doctors talk about cholesterol because it was one of the first significant blood markers they could measure and use to form correlations and hypotheses - and they simplified the topic to make it digestible to the masses (50% of whom have a below average IQ). However - the science of cholesterol is anything but simple. For example - US doctors are trying to get US citizens to lower their cholesterol levels to 'reduce the risk of heart disease' while Japanese doctors are trying to get their men to raise their cholesterol to 'reduce their risk of hemmoragic stroke.'
So what's the right level of cholesterol?
The answer is complex, and following Dr. Eades' post, you'll have a lot to consider about cholesterol. This describes the Friedewald formula used to calculate LDL levels:
"The ultracentrifugal measurement of LDL is time consuming and expensive and requires equipment not commonly available in the clinical laboratory or physician's office. For this reason, LDL-cholesterol is most commonly estimated from quantitative measurements of total and HDL-cholesterol and plasma triglycerides (TG) using the empirical relationship of Friedewald et al. (1972).
[LDL-chol] = [Total chol] - [HDL-chol] - ([TG]/5)
where all concentrations are given in mg/dL.
The quotient ([TG]/5) is used as an estimate of VLDL-cholesterol concentration. It assumes, first, that virtually all of the plasma TG is carried on VLDL, and second, that the TG:cholesterol ratio of VLDL is constant at about 5:1 (Friedewald et al. 1972). Neither assumption is strictly true." http://www.cholesterol-tests.com/Lipid_Testing_Inaccuracies.html
Why is this method of measurement a problem?
"Here is one of the problems with the Friedewald equation. Let us assume that an individual has the following lipid profile numbers: TC = 200, HDL = 50, and trigs. = 150. The calculated LDL will be 120. Let us assume that this same individual reduces triglycerides to 50, from the previous 150, keeping all of the other measures constant. This is a major improvement. However, the calculated LDL will now be 140, and a doctor will tell this person to consider taking statins!" http://healthcorrelator.blogspot.com/2010/04/friedewald-and-iranian-equations.html (BTW, this post is worth reviewing top to bottom, and includes a calculator for estimating LDL via Friedewald and an alternative method to see how far off your estimate might be).
Here's another good summary of the issue:
"Because LDL particles can also transport cholesterol into the artery wall, retained there by arterial proteoglycans and attract macrophages which engulf the LDL particles and start the formation of plaques, increased levels are associated with atherosclerosis. Over time vulnerable plaques rupture, activate blood clotting and produce heart attack, stroke, and peripheral vascular disease symptoms and major debilitating events. For this reason, cholesterol inside LDL lipoproteins is often called bad cholesterol. This is a misnomer. The cholesterol transported within LDL particles is the same as cholesterol transported by the other lipoprotein particles. The cholesterol itself is not bad; rather, it is how and where the cholesterol is being transported, and in what amounts (over time), that causes adverse effects [5]." http://en.wikipedia.org/wiki/Low-density_lipoprotein
The current thinking is that not all LDL particles are good candidates for being trapped inside the aretery walls, rather, primarily the small, dense LDL particles are. These are not identified by the standard LDL estimates.
In other words, another serious problem with the standard method for measuring LDL is that the method does not descriminate. A person with high levels of large, fluffy LDL particles is in a totally different risk category than a person with a large dose of small, dense LDL.
So, what is the "right" level of cholesterol? Well, high levels of HDL is good, LDL numbers are frequently meaningless, and thus, there's no simple answer. But all people want to avoid 'Syndrome X', or metabolic syndrome, characterized by:
-high blood pressure
-high triglycerides
-high levels of small, dense LDLs
-hyper insulinemia
-low HDL
How do we avoid this condition? Eat a lot of protein and fat, and avoid high density carbohydrates.
Don't believe me? I wouldn't ask you to. Avoid all the speculation and try it yourself through a before and after test. If you do read his post, you'll know what to ask your Dr. to clarify your results.
http://www.proteinpower.com/drmike/weight-loss/low-carbohydrate-diets-increase-ldl-debunking-the-myth/
Re-edit 17 May, 12:27 PM CDT, and 10 March, 2011
Doctors talk about cholesterol because it was one of the first significant blood markers they could measure and use to form correlations and hypotheses - and they simplified the topic to make it digestible to the masses (50% of whom have a below average IQ). However - the science of cholesterol is anything but simple. For example - US doctors are trying to get US citizens to lower their cholesterol levels to 'reduce the risk of heart disease' while Japanese doctors are trying to get their men to raise their cholesterol to 'reduce their risk of hemmoragic stroke.'
So what's the right level of cholesterol?
The answer is complex, and following Dr. Eades' post, you'll have a lot to consider about cholesterol. This describes the Friedewald formula used to calculate LDL levels:
"The ultracentrifugal measurement of LDL is time consuming and expensive and requires equipment not commonly available in the clinical laboratory or physician's office. For this reason, LDL-cholesterol is most commonly estimated from quantitative measurements of total and HDL-cholesterol and plasma triglycerides (TG) using the empirical relationship of Friedewald et al. (1972).
[LDL-chol] = [Total chol] - [HDL-chol] - ([TG]/5)
where all concentrations are given in mg/dL.
The quotient ([TG]/5) is used as an estimate of VLDL-cholesterol concentration. It assumes, first, that virtually all of the plasma TG is carried on VLDL, and second, that the TG:cholesterol ratio of VLDL is constant at about 5:1 (Friedewald et al. 1972). Neither assumption is strictly true." http://www.cholesterol-tests.com/Lipid_Testing_Inaccuracies.html
Why is this method of measurement a problem?
"Here is one of the problems with the Friedewald equation. Let us assume that an individual has the following lipid profile numbers: TC = 200, HDL = 50, and trigs. = 150. The calculated LDL will be 120. Let us assume that this same individual reduces triglycerides to 50, from the previous 150, keeping all of the other measures constant. This is a major improvement. However, the calculated LDL will now be 140, and a doctor will tell this person to consider taking statins!" http://healthcorrelator.blogspot.com/2010/04/friedewald-and-iranian-equations.html (BTW, this post is worth reviewing top to bottom, and includes a calculator for estimating LDL via Friedewald and an alternative method to see how far off your estimate might be).
Here's another good summary of the issue:
"Because LDL particles can also transport cholesterol into the artery wall, retained there by arterial proteoglycans and attract macrophages which engulf the LDL particles and start the formation of plaques, increased levels are associated with atherosclerosis. Over time vulnerable plaques rupture, activate blood clotting and produce heart attack, stroke, and peripheral vascular disease symptoms and major debilitating events. For this reason, cholesterol inside LDL lipoproteins is often called bad cholesterol. This is a misnomer. The cholesterol transported within LDL particles is the same as cholesterol transported by the other lipoprotein particles. The cholesterol itself is not bad; rather, it is how and where the cholesterol is being transported, and in what amounts (over time), that causes adverse effects [5]." http://en.wikipedia.org/wiki/Low-density_lipoprotein
The current thinking is that not all LDL particles are good candidates for being trapped inside the aretery walls, rather, primarily the small, dense LDL particles are. These are not identified by the standard LDL estimates.
In other words, another serious problem with the standard method for measuring LDL is that the method does not descriminate. A person with high levels of large, fluffy LDL particles is in a totally different risk category than a person with a large dose of small, dense LDL.
So, what is the "right" level of cholesterol? Well, high levels of HDL is good, LDL numbers are frequently meaningless, and thus, there's no simple answer. But all people want to avoid 'Syndrome X', or metabolic syndrome, characterized by:
-high blood pressure
-high triglycerides
-high levels of small, dense LDLs
-hyper insulinemia
-low HDL
How do we avoid this condition? Eat a lot of protein and fat, and avoid high density carbohydrates.
Don't believe me? I wouldn't ask you to. Avoid all the speculation and try it yourself through a before and after test. If you do read his post, you'll know what to ask your Dr. to clarify your results.
http://www.proteinpower.com/drmike/weight-loss/low-carbohydrate-diets-increase-ldl-debunking-the-myth/
More here:
http://www.clinchem.org/cgi/content/abstract/36/1/15Re-edit 17 May, 12:27 PM CDT, and 10 March, 2011
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