And Now, A Little Medical Heresy:

OK boys and girls, time to dust off those old biochemistry charts!  The topic for today is that even though it is well known HOW statin drugs work to reduce cholesterol, it is unknown WHY they reduce mortality from heart disease.

I'm going to back up a bit, and tell you something shocking: Until statins came along, there was no credible evidence that reducing serum cholesterol, whether by diet or meds, had any beneficial effect on mortality.  In fact, most of the literature tended to prove the very opposite, namely that reducing serum cholesterol actually increased mortality.  This was especially true for studies where cholesterol was reduced by restricting dietary fat.  (I'll get to this topic on another day.)

But when statin drugs came along, for the very first time, studies started to show a reliable statistical correlation between statin use and reduced mortality from all sources.  Now we've all been told, ad infinitum that the reason is because of the reducing effect statins have on cholesterol.  But I'm going to assert that because statins work by interfering with crucial biochemical pathways, nobody really knows what point (or points) in any of those pathways is (are) responsible for the beneficial effects observed from statin therapy.

From Wikipedia, here's how cholesterol is made:

Cholesterol is primarily synthesized from acetyl CoA through the
HMG-CoA reductase pathway in many cells/tissues. About 20-25% of total
daily production (~1 g/day) occurs in the liver, other sites of higher
synthesis rates include the intestines, adrenal glands and
reproductive organs."
"Cholesterol - Wikipedia, the free encyclopedia"

And here's the chart:

http://en.wikipedia.org/wiki/HMG-CoA_reductase

You can't just follow the chart from top to bottom, because the entire process is a regulating step for that little cycle at the upper left, namely, the synthesis of Acetyl Co-A.  That affects other products of this same pathway, most notably, Co-Q10 (otherwise known as ubiquinone or "UQ.")  The reduction in  Co-Q10 when taking statins is the cause of those muscle aches they warn you about in the commercials.  The muscle aches happen because  Co-Q10 is absolutely essential to life, and without it, muscles simply begin to die.

Again from Wikipedia, here's the Electron Transport Chain, showing the utter necessity of  Co-Q10 (i.e. "UQ"):

                                           

http://en.wikipedia.org/wiki/Coenzyme_Q10

The Electron Transport Chain is part of the cellular nuts and bolts of respiration. Yes, I said respiration.  Over in the lower right-hand corner of the picture, you'll notice an enzyme called "ATP Synthase."  As you remember from any biology course you ever took, ATP is the body's bottom line source of energy.  No ATP means "Entropic Doom." (Remember that great biology expression?)

ATP Synthase is not the main source of ATP in humans.   That status belongs to the Citric Acid Cycle, which I'm sure you also remember.  Again, I'm going to show you a chart from Wikipedia, because I want you to see that Acetyl-CoA is a sine qua non of this process (Upper left corner):

http://en.wikipedia.org/wiki/File:Citric_acid_cycle_with_aconitate_2.svg

Remember that statins interfere with the main pathway for regulating Acetyl CoA.

Bottom line: Statins disrupt/modify various crucial biochemical pathways that are utterly basic to life. In each of these pathways there are many steps, and each of the successive steps is regulated/limited by the presence or absence of reactants in the previous steps.

So now you tell me: How does anyone know which step is the one that results in a health benefit?  As you can see, there's no definite cause and effect.   For various reasons many researchers desperately wanted to see the benefit arising from the reduction in serum cholesterol.  But without further reliable proof, that's just wishful thinking.  I don't know whether it's the lowered cholesterol that's helping (I doubt it.)   And neither does anyone else.