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BLOG: July 2008

Is "good" cholesterol good for memory?

So called "good" cholesterol is cholesterol transported by high-density lipoproteins (HDL, consisting of lipids attached to a protein carrier, hence the name) to the liver, to be disposed of. In a recent study on 3700 British men and women (Singh-Manoux et al.) the researches established possible link between low level of "good" cholesterol and increased risk of memory decline by the age of 60.

Both, researchers and the news headline put it as "good" cholesterol being possibly protective against age-related deterioration of memory. If true, it would further solidify the current view of "good" cholesterol being, generally, health protective.

But - something doesn't add up here. If the body benefits from something being taken out of the system more expeditiously, that "something" can only be bad, correct? This oxymoron is more than just semantics. It reflects misunderstanding - or ignorance - of what is actually the role of cholesterol in our bodies and, consequently, the meaning of specific nominal levels and relative balance between "good" and "bad" cholesterol.

"Good" cholesterol cannot protect your memory, or anything else, simply because it is something being taken out of your system. The significance of the nominal levels and the ratio of "good" to "bad" cholesterol is that they give

indication of what is taking place inside your body.

And we can get a good idea of what it could be by looking back on what is it that the body uses cholesterol for. Sounds logical, doesn't it?

After genetics, thyroid or fat metabolism malfunctions are ruled out, the relative increase in cholesterol supply ("bad" vs. "good" cholesterol), indicates that the body needs and uses more of it than usual. Also, it indicates an ongoing cholesterol buildup within the body.

And vice versa, the relative increase in blood cholesterol due to higher rate of cholesterol disposal ("good" cholesterol) indicates that the body gets by without the need for chronically higher use of cholesterol.

The question is,

what is it that the body uses cholesterol for?

In other words, what are the possible causes, tissues/organs and consequences of cholesterol accumulating within the body. We won't go into incredibly complex details of body metabolism in general, and cholesterol metabolism in particular, but we can establish some useful general leads.

Let's begin with where most of body's cholesterol is: cellular membrane. Cells use cholesterol to fine-tune their membrane fluidity; incorporating more cholesterol into the membrane makes it more stiff, generally more resistant to everything entering the cell - or attempting to - from the outside, and vice versa. It is quite probable that damaged, or threatened cell would respond by stiffening its membrane, trying to protect its integrity. In other words, by using up more cholesterol.

The three primary agents inflicting damage to the cellular membrane are free radicals, pathogens and toxins, including trans fatty acids. Each of them can - and usually does - trigger inflammatory response. Thus, the buildup of cholesterol indicates that there is

significant portion of body cells suffering oxidative damage, bio-attack, toxic exposure and/or inflammation.

From this point on, it is only a matter of appropriate lab tests to find out where are the focal points of this process, and design the appropriate therapy.

Cells forming the inner blood vessel lining (epithelium) are probably among the most exposed to these damaging agents - to which here we can also add homocysteine - since it is the blood where these agents first arrive from the intestine and lungs. Obviously, inner intestinal and bronchial tube linings are also highly exposed, and so are the organs filtering the blood - liver and kidneys.

This would explain why, for instance, probiotic intestinal bacteria, by reducing degree of intestinal toxicity/inflammation, as well as reducing toxicity of the blood due to (probable) leaky gut, can be helpful in normalizing cholesterol levels.

And how does memory protection play into this? Well, the brain is organ with the highest lipid concentration in general, and highest cholesterol concentration in particular. As such, it is particularly vulnerable to fat-soluble toxins, which the body cannot entirely eliminate. Consequently, they accumulate - you guess right - in body's fatty tissues.

Now, "good" cholesterol, being withdrawn out of the body, has no role in any of it; it is only "bad" cholesterol, the one supplied to the body, that the brain cells can attempt to use in order to protect themselves by stiffening the membranes.

At the same time, the rate of release of cholesterol from cell membranes is, for the same reason, likely to decrease, lowering body's cholesterol output ("good" cholesterol).

So, the first thing you should be concerned about if your cholesterol levels are elevated, and your good-to-bad cholesterol ratio worsened, is possible - and probable -

excessive oxidative, inflammatory and/or
toxic damage to your cells,

especially those in the above mentioned most exposed/vulnerable tissues and/or organs, and within the organ with the highest cholesterol concentration - your brain.

If it is going on inside your blood vessels, it will result in buildup of repair proteins (fibrinogen), cholesterol and calcium, causing atherosclerosis and cardiovascular disease. If it is affecting the brain, it will likely cause some degree of damage to its function, including possible accelerated memory decline.

Another, rather common source of elevated cholesterol is getting too much of it from the diet, either directly (preformed), or as a result of excessive caloric intake. Consuming excessive amounts of animal fats will raise body cholesterol levels, unless the body adjusts its own production accordingly.

Such adjustment takes place in about 2 in every three individuals, on the average; so the chances that you are not significantly affected by your dietary cholesterol intake are good, but you can't count on it. Replacing cholesterol-containing animal fats in your diet with unsaturated plant fats could lower your "bad" (supply) cholesterol.

Indirectly, excessive caloric intake and following metabolic breakdown of carbohydrates, fats or even proteins results in the build-up of 2-carbon acetates in the liver, used by it for cholesterol production; thus eating too much by itself could stimulate the liver to produce more cholesterol.

Yet another source of excess cholesterol is chronic stress. Since the body needs cholesterol to synthesize stress hormones, it does stimulate cholesterol production ("bad" cholesterol). As these elevated stress hormones are metabolized (broken down) in the liver, they are transformed/transferred into the bile, and excreted into intestines. If, however, the intestinal fiber content is very low, nearly all of the bile - including cholesterol - will be reabsorbed and returned to the bloodstream.

Thus degree to which chronic stress elevate body's cholesterol levels depends - just like about every possible negative impact on health - on the quality of your diet.

Stress also depletes the body of nutrients, including detox and immune nutrients, as well as antioxidants, fueling by that oxidative, inflammatory and toxic damage to the cells. In addition, it negatively affects the efficiency of immune system in suppressing cellular damage inflicted by pathogens. This, in turn, tends to draw in more ("bad") cholesterol from the liver, and slow down the pace at which the body disposes of it.

Of course, all cholesterol that body channels into the bile, not only the small portion coming from metabolized stress hormones, would be reabsorbed in the absence of dietary fiber.

Note that adrenal hormones, like cortisone, are also also needed to regulate inflammatory process. These hormones are also made of cholesterol. This is one more mechanism through which inflammation - and therefore excessive cellular exposure to oxidative, toxic or pathogen exposure as well - tends to stimulate liver cholesterol production, contributing to elevated cholesterol levels (as many of us know, suppressing inflammation is one of the common purposes of cortisone injections).

These are only brief outlines of some of the main possibilities of a meaningful interpretation of the causes and health effects of body's cholesterol levels. Hopefully, both media and (some) researchers will move beyond the point of skin-deep interpretations, such as, for instance, stating that "good" cholesterol "protects this", or "has a role in that". It is good to know what is actually taking place in your body.