The Cholesterol Quandary

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We have all heard that high levels of cholesterol are dangerous. In one TV ad, viewers see a seemingly healthy person collapsing on the street because of a high cholesterol level. Another TV ad shows a man parading around telling everyone "I've lowered my cholesterol." But are high cholesterol levels as important as advertised? Not everyone with high cholesterol levels has a heart attack. And conversely, some people with low cholesterol levels have heart attacks. Are there other factors which need to be considered?

RATIOS
Doctors are concerned not only with your cholesterol level, but the ratio of high density cholesterol levels (HDL) compared to low density cholesterol levels (LDL), using the ratio as a risk factor in cardiovascular disease (CVD). But new research is now showing that another cholesterol factor may be a better indicator of CVD than cholesterol levels or ratios.

PARTICLE SIZE
A study done in Quebec, Canada indicates that the increased risk of CVD is not only affected by the levels of LDL in the blood but the size of the LDL particles. They found that increased amounts of small LDL particles were associated with a marked increase in the risk of CVD--even in the presence of normal LDL levels.

In other words, one person could have the same total LDL blood levels as another, but one could have a larger number of small LDL particles. This is because conventional lipid tests measure the amount of cholesterol in the LDL fraction of the blood, not the particle size. The Quebec study indicated that the smaller, more dense LDL particles were more dangerous than the large, buoyant LDL particles.

TRANS FATS AFFECT LDL SIZE
A study recently reported in the American Journal of Clinical Nutrition (AJCN) on the effects of trans fats in the diet and cholesterol, produced some interesting results. Cholesterol in the blood of people was analyzed after consuming five experimental diets for 35-day periods. The diets consisted of fat from butter or four varying degrees of trans fats. This study found that the LDL cholesterol particles decreased significantly in size with increasing amounts of dietary trans fat intake.

Trans fats are formed during the hydrogenation of vegetable oils--a process that changes oils into semi liquids or solid fats. Examples of trans fat foods are deep fried foods, some pastries, margarine, donuts and French fries.

Interestingly, the AJCN trans fat study also found that even though the butter diet (saturated fat) was associated with the highest blood LDL concentration, the LDL particles found were the largest. They also found that the subjects with the highest plasma triacylglycerol concentrations also had the smallest LDL peak particle size.

Another link in the LDL particle size question appeared in an October 2003 study in the Journal of the American Medical Association (JAMA). This study investigated a group of people who characteristically have exceptional longevity and lower incidence of age-related disease.

In comparing their blood and offspring's blood levels of HDL and LDL to other adults, they found the individuals with exceptional longevity had larger HDL and LDL particle sizes. A biologist at the National Institute on Aging stated, "These findings are striking. If I were a drug company reading this, I'd want to (find agents that) modify particle size."

A paper presented at the American Heart Association convention in November 2003 stated that clinical practices normally measure the amount of LDL cholesterol (which is contributed mainly by large particles) and not the number of particles (which could indicate the presence of small LDL particles). Two people could have the same levels of LDL cholesterols, but one could have a greater number of small, high-risk CVD particles.

What is the danger of small LDL particles? LDL particles contribute to arteriosclerosis by attacking the arterial wall. An excessive number of LDL particles circulating in the blood promotes movement into the subendothelial space and formation of plaques. When the number is low, particle movement is reduced, resulting in decreased risk. (See figure 1.)

So how do we reduce the number of small LDL particles in our systems? One way, already mentioned, is to avoid the consumption of trans fats (hydrogenated or partially hydrogenated vegetable oils such as soy bean oil, corn oil, etc.). Avoid deep fried foods, including French fries and donuts.

Dietary intake of fish oil has been reported to have the effect of changing LDL particle size. A 2000 AJCN study stated that docosahexaenoic acid (DHA) supplementation significantly increased LDL particle size. Eicosapentaenoic acid (EPA) did not have the same effect but both EPA and DHA reduced blood levels of triglycerides. DNA and EPA are abundant in cold-water fish oils.

A second recent study indicates niacin also may be beneficial in effecting a shift in LDL particles from the small dense particles to large benign particles.

What will the future bring us in the new concept of what is the "bad cholesterol" and what do we do about it? I am anxious to learn!

DIAGRAM: Figure 1.

References:
AJCN (Nov. 2000). Vol. 71pp. 1085-94.

JAMA (Oct. 15, 2003). Vol. 290 No. 15.

Science News Org. (Oct 18, 2003). Vol. 164.

AJCN (Nov. 2003). Vol. 78 pp. 370-5. Circulation (2001). Vol. 104 pp. 2295-9.

AHA 76th Annual Sessions (Nov 2003). Otros, Cromwell, Shataurovd Lipo Science, Inc.

N. Eng. Jour. Med. (Nov 27, 2003). Vol. 349, No. 22 pp. 2089-90.

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By John Carlson, President of JR Carlson Laboratories, Inc.

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