All About Triglycerides: An Interview with Dr. Michael Miller

Editor’s Note: A scientific statement published today in Circulation: Journal of the American Heart Association found that dietary and lifestyle changes significantly reduce elevated triglycerides, a type of blood fat, which is associated with heart, blood vessel and other diseases.

So what exactly are triglycerides, how significant are this statement’s findings and what specific steps can people take to reduce their triglyceride level and improve their heart health? Dr. Michael Miller, chair of the AHA’s statement committee, a cardiologist at the University of Maryland Medical Center and director of the Center for Preventive Cardiology at the University of Maryland School of Medicine, answers those questions and more to help you improve your triglycerides IQ.

As compared to lowering cholesterol, it sounds like lifestyle changes can go a long way toward lowering cholesterol levels.

Yes, lifestyle changes may only lower cholesterol 5-10% while they can lower triglycerides 30-50% and higher in some cases!

How significant are these findings, and why should people care and take action?

This is the most comprehensive statement on triglycerides and puts into perspective the important role that they serve as a barometer of our “metabolic” health. Optimal triglycerides suggest that fat is being effectively broken down whereas high triglycerides indicate abnormal processing, which may lead to excess fat in other tissues.

For example, excess fat in muscle may lead to insulin resistance and diabetes, excess fat in the liver may produce a fatty liver and excess fat in the belly may produce inflammation and increase risk of heart disease. In fact, a high triglyceride level may predict development of diabetes years down the road. Therefore, it is important that people pay close attention to their triglyceride level, especially because it can often be effectively treated with lifestyle measures.

What are triglycerides, and why are they important?

Triglycerides are simply our fats and high triglyceride levels in our blood tell us that our body is carrying around too much unhealthy fat. Too much unhealthy fat in our blood is associated with an increased risk of diabetes and heart disease.

Talk about the work your committee did, as well as the key findings.

Our committee of 15 men and women physician scientists evaluated more than 500  studies involving triglycerides during the past 30 years. In summary, our findings indicate that triglycerides are an important marker for heart disease risk.  High triglycerides may raise the risk of heart disease 20-50% and double the risk if accompanied by high levels of LDL (the bad cholesterol). High triglycerides are also associated with increased belly fat, high blood pressure, insulin resistance and low levels of HDL (the good cholesterol).

How are and how often should triglycerides be measured?

Screening levels can now be obtained in a non-fasting state and depending on the results will determine whether additional testing should be performed. For example, a normal non-fasting test (less than 200) may not need additional testing for a period of 1 year or greater, whereas high levels (200 or greater) should have a fasting test within a reasonable period such as 2-4 weeks.

It sounds like triglycerides are somewhat similar to cholesterol. Can you talk about that, as well as why the public is so familiar with lowering its cholesterol levels but not its triglycerides?

Cholesterol is a waxy substance whereas triglyceride is fat, but they are both connected by the lipoproteins that transport them to and from various body tissues. For example, triglyceride-rich lipoproteins include chylomicrons (that transfer triglycerides after a fatty meal) and VLDL (very low density lipoprotein) that transfers triglycerides from the liver. The triglycerides are broken down and stored in fat or used as an energy source in muscle. Cholesterol-rich lipoproteins include LDL and HDL and they transfer cholesterol to or from body tissues.

What are the current guidelines for triglyceride levels, and what is the optimal level?

In addition to the previous guidelines that define desirable levels (less than 150), borderline-high (150-199), high (200-499) and very high (500 and greater), we have now added the optimal level of less than 100.

What can people do to lower their triglyceride levels?

High triglycerides are very responsive to lifestyle changes. They include reducing weight if overweight by decreasing the total number of calories eaten daily, reducing simple sugars, especially fructose, decreasing saturated fat and eliminating trans fats. Physical activity, especially aerobic exercise, will also lower triglyceride levels.

Are there specific foods people should eat more of and avoid, and forms of exercise that are better than others?

Omega-3 fats that contain EPA and/or DHA such as found in fatty fish can lower triglycerides. Decreasing simple carbohydrates, saturated and trans fats are also recommended. Aerobic activity is also effective in reducing elevated triglycerides.