by Kristine L. Soly, MD, FACC
Cholesterol and triglyceride have such a bad reputation that the very words conjure up an image of blobs of fat (like those congealed on cold soup) lurking in the blood stream ready to attack the first available artery. It’s so bad that people feel guilty or ashamed if their levels are elevated. Articles regularly appear about cholesterol and triglyceride, as if it were something we all really understood. But nothing could be further from the truth.
Not even physicians or scientists understand all we need to know about this complex issue. New data is constantly emerging, resulting in changes in recommendations. Hence the confusing (and often conflicting) advice from the medical community over the past decade that has left patients uncertain about what to do.
Cholesterol and triglycerides are not bad substances. They are natural and normal substances in the body and are essential components. We could not survive without them.
Cholesterol is not a fat. It is a white, waxy substance, which is soluble in fat (but not in water). Each cell can synthesize its own cholesterol, which is used to regulate the rigidity of every cell membrane. In addition, the liver manufactures about 3000 mg. of cholesterol every day, which is used to produce the sex hormones (estrogen, progesterone, and testosterone) and adrenal hormones (aldosterone and cortisone), to make vitamin D and bile, to constantly assure proper cell repair throughout the body, and to serve as an antioxidant when vitamin and mineral stores are low.
Triglyceride is fat, and it also is not soluble in water. Triglycerides are our main source of energy, and a layer of triglycerides make up the cell membranes of all of our cells, which enable them to function normally.
Cholesterol and triglyceride are called lipids. Though they are not necessarily bad for us, they get their bad reputation because of their association with saturated animal fats. After consuming meat or dairy, lipids (triglyceride and cholesterol) are absorbed by the intestines and enter the blood stream. From here they go to the liver and to the rest of the body.
Since the blood is essentially water, and since triglyceride and cholesterol are not water soluble, they must be transported in the blood in carriers that can dissolve in water. These carriers are called lipoproteins, which are made by the liver. As their name suggests, lipoproteins are composed of lipids and proteins. The lipids making up lipoproteins are mostly cholesterol and some triglyceride. Hence, all lipoproteins contain cholesterol and triglyceride, even if they are not transporting them. When your total cholesterol or triglyceride is measured, that number includes all that is contained in the lipoproteins–that which is part of the carrier as well as that which is being transported.
But since your blood is drawn 10-12 hours after your last meal, all the cholesterol and most the triglyceride you ate have been delivered to cells and are no longer in circulation. But, the lipoprotein carriers are still in the blood stream, so the cholesterol and triglyceride that make up the lipoproteins are what is measured.
Problems arise when there are too many of some (but not all) lipoproteins in the blood stream. Certain lipoprotein carriers in the blood stream get into the arterial wall when the inner lining of the blood vessel (the endothelium) is damaged. The body perceives these as foreign invaders and sends in white blood cells (macrophages) to gobble them up. The macrophages with engulfed lipoproteins (called foam cells) cause plaque to develop (atherosclerosis), which subsequently causes heart attacks, strokes, and other problems with arteries. Only those lipoproteins that become part of a foam cell are problematic. Hence, lipid disorders are really disorders of the lipoproteins that are involved in foam cells.
There are a number of lipoproteins in the body. Chylomicrons transport cholesterol and triglyceride from the intestines, but only exist for a few minutes after eating so are usually not measured. Very low-density lipoproteins (VLDL) transport cholesterol and triglyceride, breaking down into cholesterol-laden LDL after delivering the triglyceride to cells. Low-density lipoproteins (LDL) transport cholesterol to cells. High-density lipoproteins (HDL) transport LDL from the blood stream back to the liver. After all the cholesterol and triglyceride have been delivered, the primary lipoproteins left in the blood stream are LDL and HDL.
LDL cholesterol is called the “bad” cholesterol because some forms of it can oxidize and become involved in the formation of foam cells that cause plaque in the arteries. HDL cholesterol is called the “good” cholesterol because one of its subgroups (HDL 2b) takes LDL out of circulation and protects from the development of plaque.
We also know that there is something called Lipoprotein(a), also called Lp(a), which is an LDL with an extra adhesive protein wrapped around it. This is a “really bad” form of LDL that has a strong correlation with the formation of foam cells and plaque. Unfortunately, this lipoprotein is largely acquired by heredity, though lifestyle definitely plays a role.
To further complicate matters, we now know that LDL (the “bad” cholesterol) comes in more than one size (LDL Pattern). There are large fluffy LDL’s (called Pattern A) that are thought to be benign. Then there are the small dense LDL’s (called Pattern B) which have a strong association with atherosclerosis. So, not all LDL cholesterol is bad! This might explain how someone might have high LDL without atherosclerosis (Pattern A) and someone else might have low LDL with very aggressive atherosclerosis (Pattern B). Both heredity and lifestyle determine the LDL pattern.
Simply knowing your total cholesterol level does not provide enough information to decide whether you’re at risk for atherosclerosis. Nor does just knowing your LDL and HDL levels. You need to know your Lp(a) level, how much of both LDL pattern A and LDL pattern B you have, and how much HDL 2b you have.
Additionally, it’s not just the cholesterol levels that you need to know–elevated triglyceride is a problem for atherosclerosis also. Triglycerides that are transported in your body by a form of very-low-density lipoprotein (VLDL 3) and by an intermediate lipoprotein (IDL) are strong stimulants of foam cell formation, and hence plaque. VLDL3 and IDL are known collectively as Remnant Lipoproteins (RLP).
It is desirable to have low levels of both cholesterol and triglyceride. However, with cholesterol, it is best to have low levels of only the LDL-cholesterol and high levels of the HDL-cholesterol. With LDL-cholesterol, it is best to have low levels of Pattern B and Lp(a). For HDL, it is best to have high levels of HDL 2b. And, with regard to triglycerides, it’s best to have low levels of RLP (VLDL3 and IDL).
Dr. Soly is board certified in Cardiology, Internal Medicine, and Holistic Medicine, and is a Fellow of the American College of Cardiology. She practices Holistic Cardiology and is director of the Holistic Cardiology Learning Center at 220 Andrews Lane, Crossville, TN.
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