Introduction

After we have digested all the health information about total, 'good', and 'bad' cholesterol, there is still another blood lipid that we may have to worry about. Serum triglyceride levels are often neglected, but they can be important. Professor Anita Rieder, MD, of the Institute for Social Medicine and Cardiovascular Diseases, University of Vienna, Austria, has recently published a review of raised triglyceride levels in her newsletter. We are pleased to reproduce it here, in two parts. (Robert Griffith, Editor)

What are triglycerides?

Triglycerides (TGs), as well as cholesterol, belong to the blood fats (plasma lipids). Since fats don't easily dissolve in watery fluids, they tend to bind to the proteins present in the blood. This results in the formation of the so-called "lipoproteins", which transport not only the triglycerides through our bloodstream but also other fats, including the cholesterols.

Triglycerides are neutral fats and important sources of energy for the body. They are made up of glycerol and fatty-acid molecules. The triglycerides in our blood are either synthesized from our food intake, or else produced by the liver, as our body continuously needs energy and dietary fats are not always available. Most of those dietary fats as well as the fat stores in our adipose tissue ("energy stores") exist in the form of triglycerides.

Triglycerides are broken down into free fatty acids, which either provide an instant source of energy for the body or are recycled back into triglycerides or stored in the adipose tissue.

Serum levels of triglycerides are considered as being:

• normal: if less than 150 mg/dL (1.7 mmol/L),
• borderline high: if between 150 and 200 mg/dL (1.7 -- 2.2 mmol/L),
• high: if between 200 and 500 mg/dL (2.2 -- 5.6 mmol/L), and
• very high: if they are 500 mg/dl or more (5.6 mmol/L or above).

What causes raised triglyceride levels?

Elevated TG levels in the blood (hypertriglyceridemia) can have many causes, involving disturbances of either the breakdown or the build-up stages of the metabolic processes. High TG levels are obviously always associated with an increase in the number of the triglyceride-rich protein molecules that transport the TGs through the bloodstream. And as they also function as carriers for cholesterol, hypertriglyceridemia is often associated with hypercholesterolemia (a pronounced increase in cholesterol levels).

Very high triglyceride levels nearly always point to a genetic disorder involving fat metabolism. Affected individuals usually have TG values between 500 and as much as 10,000 mg/dL, and often have also high readings for total cholesterol. These genetic conditions fall into the category of the so-called "primary lipidoses" (disorders of fat metabolism).

On average, levels above 1,000 mg/dL (11 mmol/L) can be found in one out of 5,000 individuals. But there are also various acute medical conditions, like acute pancreatitis, that can lead to very high TG levels; such patients will usually present with values around 4,000 - 5,000 mg/dL (around 50 mmol/L).

Among the most common causes for "secondary lipidoses", which implies an elevation of TG levels, are an unhealthy diet, excessive alcohol consumption, diabetes, underactive thyroid, severe kidney failure, liver disease, and certain medications and hormone treatments.

Elevated TGs are also part of the overall medical picture of the "metabolic syndrome" (also known as "syndrome X"), which by now is well known to readers of these pages (see link below).

The most common diet-related cause of hypertriglyceridemia is excessive consumption of sugar in the form of sugary drinks and sweets. Drinking alcohol will increase the TG plasma levels - if you drink alcohol in the evening, you will have elevated TG levels the following morning. Compared with someone with TG values in the normal range, an individual that already has a persistently high TG level will boost his/her hypertriglyceridemia quite disproportionately. An additional effect of alcohol is that it causes a pronounced rise of TG levels after a meal. A fat-rich meal accompanied by alcohol is therefore particularly unhealthy for those already suffering from hypertriglyceridemia.

How common is hypertriglyceridemia?

How frequently does hypertriglyceridemia occur in men and in women? Statistical data collected in the USA suggest that almost one quarter of their population is affected by the metabolic syndrome. This proportion reaches 40% in the age group 40+. In the age group between 40 and 60, it is a condition that is definitely found more frequently in men than in women.

As far as TGs are concerned, 30% of the population has elevated values, with 35% found in men, compared with 25% in women. A study analyzing the results of different series of screening tests showed that 20% of all male participants who before the check-up had claimed to be in perfect health had, in fact, elevated TG values.

In my next article . . .

Elevated triglycerides represent an important risk factor for heart diseases. However, we must make a distinction between "good" and "bad" triglycerides. In the next article I will explain how to tell the "good" triglycerides from the "bad" ones, and how to minimize the risk from hypertriglyceridemia.