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 man and woman (Singh-Manoux et al.) the researches established that there is a possible link between low level of "good" cholesterol levels and increased chances of memory decline by the age of 60. Both, researchers and the news headline formulated it as "good" cholesterol possibly protecting your memory from deteriorating.

This fits into general notion that low "good" cholesterol level is, generally, not good for health, and vice versa.

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 ratio of "good" and "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 genetic, thyroid or fat metabolism malfunctions are ruled out, increase in total cholesterol with the ratio of cholesterol supply ("bad" cholesterol) vs. cholesterol disposal ("good" cholesterol) either nearly unchanged (normal), or higher, indicates that the body needs and uses more of it than usual. Also, it indicates an ongoing cholesterol buildup within the body, especially when the ratio of cholesterol input ("bad") vs. output ("good") is higher.

The question is, what are the possible causes, locations and consequences of this cholesterol buildup. 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 cellular damage are free radicals, pathogens and toxins. Each of them can - and usually does - trigger inflammatory response. Thus, the buildup of cholesterol indicates that there is significant number 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. 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 bad-to-good cholesterol ratio worsened, is possible - and probable -

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

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.

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 (in such case, partly replacing cholesterol-containing animal fats with unsaturated plant fats should lower body cholesterol).

Such adjustment takes place in about 2 in every three individual, on the average; so the chances that you are unaffected by dietary cholesterol intake are good, but you can't count on it.

Indirectly, excessive caloric intake and following break-up of carbohydrates, fats or even proteins results in the build-up of 2-carbon acetates in the liver, the building blocks from which it manufactures cholesterol; this could stimulate the liver to divert more of these break-up by-products into production of 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 bile, and excreted into intestine. If, however, 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 cholesterol, and slow down pace at which the body disposes of it.

Of course, all cholesterol that body channels into the bile, not only 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. This is one more mechanism through which inflammation - and therefore excessive cellular exposure to oxidative, toxic or pathogen exposure as well - tend 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 to a meaningful interpretation of the causes and health effects of disturbed 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. Especially when it comes to your health. R