ASK DR LAURO

(If you have questions you would like Dr. Lauro to answer, send them to healthy outlook@meridianmagazine.com)

Dear Dr. Lauro:

What is the ideal cholesterol level?  How do you figure the ratio between LDL and HDL and determine if they are healthy?  How can you lower the triglyceride levels in the blood and what does a high level mean?  Elaine Dalton.

Dr. Lauro responds:

There are several types of fats in the body.  These fats originate either through ingestion (our diet) or through synthesis in our liver.  Either way, these fats circulate through the bloodstream on their way to the fat cells for storage.  Having excessive amounts of fat in the bloodstream is detrimental to the arterial wall.  This is where fats do their damage as they irritate and inflame the cells which line the inside of the artery.  This inflammation leads to scar tissue formation, which then becomes calcified and hard (hardening of the arteries).  This calcified mass of scar tissue and fat is called “plaque”.  These plaques, as they grow bigger and bigger, can narrow the arteries and reduce blood flow through them, thus depriving the organs of necessary oxygen and nutrition.  Even worse, these plaques, as they stick out into the blood vessel opening (the lumen), can trap platelets (the blood clotting cells of the body) and lead to a blood clot, which can completely occlude the artery.

When the coronary arteries, which feed the heart itself, become partially blocked by fatty plaque, they can cause diminished blood flow to the heart and thus cause “angina” (low oxygen supply to the heart muscle causing cell damage, but not cell death.). 

Even worse, however, is the situation where the coronary arteries become completely blocked by a clot, which has formed on a fatty plaque.  This totally occludes the lumen of the coronary artery and leads to “heart attack” (the situation where the heart muscle cells actually die because of the lack of blood flow, also called “infarction”).

When these occlusions happen to an artery up in the brain it causes stroke (“brain attack” or cerebral infarction).  These occlusions can also affect the arteries in the eye (blindness), the kidney (kidney failure), and the extremities (pain in the legs for example when you try to walk distances).

But, you might ask, doesn’t everyone normally have fat flowing through his or her bloodstream?  Yes, but it is the types of fat and the amounts of fat which get us into trouble.  Some types of fat are actually very healthy (HDL cholesterol, for example).  But the wrong kinds of fat (LDL cholesterol, for example, which comes from saturated or animal fat) can be devastating to the arterial wall’s ability to cleanse itself and replace injured or dead cells. This leads to the buildup of plaque that we discussed above.  By the way, HDL cholesterol enhances the arterial wall’s ability to cleanse and repair its endothelial lining—it does just the opposite of LDL cholesterol.

We have come to realize in the past few years that LDL cholesterol is not the only fatty culprit.  Triglyceride (good old body fat) can be converted into LDL cholesterol in the liver and thus it too, is a risk factor for plaque buildup.  Triglyceride is the fatty substance that givers meat its marbling.

Newer studies have also implicated trans-fatty acids as being very damaging to the arterial wall.  These are the man-made fats that result when scientists turn food from a liquid vegetable oil into a semi-liquid oil (the stuff you cook French Fries in) or into a solid oil, like margarine or Crisco.  These trans-fatty acids are also called “partially hydrogenated fats”.

Other factors which accelerate or add to the damage of the arterial wall done by cholesterol and triglyceride are: uncontrolled diabetes (major risk factor for arterial disease); smoking (another big risk factor); uncontrolled hypertension (yet another huge risk factor); obesity; sedentary life style; being a male; and advancing age.

Next week we will discuss what one can do about controlling cholesterol and other risk factors.