Introduction

Serum triglyceride levels are often neglected, but they can be important. In the first of these two articles, Professor Anita Rieder, MD, of the Institute for Social Medicine and Cardiovascular Diseases, University of Vienna, Austria, reviewed the nature of triglycerides and the causes of hypertriglyceridemia. Here she discusses "good" and "bad" triglycerides, and how to manage increased triglyceride levels. (Robert Griffith, Editor)

Are there "good" and "bad" triglycerides?

Scientific studies have revealed that elevated blood levels of triglycerides (TGs) increase the risk for coronary artery disease, apparently by accelerating and enhancing coronary atherosclerosis.¹ One can thus conclude that the opposite must also be true, and that a lowering of triglycerides is bound to decrease this cardiovascular risk. Most studies of this sort have been conducted in men.

In the Physicians Health Study the male subjects suffering from coronary disease generally had elevated triglyceride values. The researchers found that these high TG levels were usually associated with two other proven risk factors, namely low levels of HDL-cholesterol (the "good" cholesterol) and elevated LDL-cholesterol values (the "bad" cholesterol), including in this case a particularly dense form of LDL-cholesterol (very-low-density-lipoprotein-cholesterol) that is known to definitely accelerate atherosclerosis.

Even after re-analyzing the results of these studies after eliminating the effect of other risks factors resulting from lipid profiles, elevated TG values remained as an independent risk factor, especially for heart attacks due to coronary atherosclerosis.

Elevated triglycerides - an independent risk factor

In the Physicians Health Study men with triglyceride values ranging between 250 and 300 mg/dL (2.28 to 3.39 mmol/L) were 2½ times more likely to have a heart attack than men with normal values (50 to 100 mg/dL, or 0.45 to 1.15 mmol/L). Another study, the Copenhagen Male Study, showed similar results.

Males participating in the Helsinki Heart Study showed a particularly strong risk for coronary disease if their triglyceride levels were higher than 201 mg/dL (2.3 mmol/L) and the ratio between LDL-cholesterol and HDL-cholesterol exceeded 5. This handy risk indicator can easily be calculated by dividing the LDL-cholesterol value by the HDL-cholesterol value; it shows that the risk increases if the values for the "bad" cholesterol are high and if, conversely, the "good" cholesterol is low.

Researchers can cast less light on the relationship between elevated triglycerides and the risk of stroke. What we do know is that in all age groups and in both sexes elevated TG readings are associated with a slightly higher stroke risk (see link below). It seems that as far as the TG-induced risk aggravation is concerned we probably must also distinguish between "good" and "bad" plasma lipids. But instead of calling them "good" triglycerides we should rather speak of "benign" triglycerides, since compared with the truly "bad" TGs they cause less trouble for the heart.

Now the "bad" TGs are really associated with a significantly higher heart disease risk. They are present in high levels, for instance, in case of hereditary hyperlipidemia, if the levels of "good" HDL-cholesterol are distinctly low, and in subjects suffering from diabetes mellitus or the metabolic syndrome.

Triglycerides can be termed "benign" if the elevated plasma levels are caused by excessive alcohol consumption, bad dietary habits or by medication (in women taking estrogens, for instance). Such a condition may also be due to a hereditary condition, so-called familial hypertriglyceridemia.

Your triglyceride readings are high - what you can do

The experts from the US National Cholesterol Education Program suggest trying the following:

• If your triglyceride levels are borderline high (150 - 200 mg/dL or 1.7 - 2.2 mmol/L), your main goals should be to reach your ideal body weight and to step up your physical activities.
• In the case of readings above 200 mg/dL (2.2 mmol/L) you are at an increased risk, and will need medication in addition to lifestyle changes (diet, exercise). Treatment will depend on the levels of "bad" cholesterol, and in choosing a medication your doctor will take into account the other numbers in your blood lipid profile.

Do men benefit more than women from changes in lifestyle?

Let's discuss the lifestyle changes that are indispensable in order to cope with hypertriglyceridemia. Obviously, they will depend on the cause for the elevated TG readings. Thus overweight individuals will need to lose weight and to exercise more, they will have to cut down on sugar, cut out alcohol completely or at least reduce their alcohol intake considerably. Please see the link below for advice on this ('Losing Weight the Healthy Way').

These modifications in lifestyle are somewhat more effective in men than in women. For instance, it's been seen that overweight men who had changed their eating habits and lost weight -- about 9-18 lbs, or 4-8 kg a year -- the weight reduction alone resulted in a lowering of triglycerides by 8%. If they also took up exercising, the loss amounted to 33%. In women, a weight loss alone had no effect on the triglycerides, and a combination of weight reduction and additional exercise was only moderately successful.

Final Comment

All available information points to the need for you to have your blood lipid levels checked regularly in order to detect and control this particular cardiovascular risk in time. Are you sure to know your triglyceride levels? If not, maybe it's time for another check-up?