Cholesterol and Triglycerides

Cholesterol and triglycerides are lipids or fat like substances that are found in the human body. Cholesterol is an essential nutrient for adolescents as it is needed to manufacture certain hormones including testosterone and estrogen, it is essential to the synthesis of vitamin D which is necessary for healthy bones and it is also utilized to repair the membranes around our cells. Triglycerides are molecules of fat that are enclosed along with cholesterol during transport in the bloodstream. When cholesterol and triglycerides and some other fats are transported together in the blood, they are packed together in bodies that are termed lipoproteins.

There are two different lipoproteins that have important health concerns for adolescents. Low-density lipoprotein (LDL) can be thought of as a villain. When cholesterol is transported in this manner, it can interact with the walls of one’s arteries and become destructive. If LDL cholesterol collects on the wall of an artery, it can trigger white blood cells to collect at the site and this apparently produces a fatty substance that is called plaque. Over time, the artery can narrow and this will reduce blood flow. Calcium may also collect at the site and this could produce a blood clot. The reduced blood flow may produce signs of heart disease, and a blood clot in the coronary arteries that supply blood to the heart muscle may cause a heart attack.

The cholesterol with the “white hat,” the high-density lipoprotein (HDL) is protective. The HDL cholesterol removes cholesterol from the walls of the arteries. High levels of HDL cholesterol seem to protect the arteries from narrowing and also seem to protect the individual from heart attacks.

Cholesterol comes from the diet primarily through the intake of animal products, and it is also manufactured by the liver. There is a direct relationship between the teen’s blood cholesterol level and the amount of saturated fat in his or her diet. Saturated fats are found in animal products that include butter, red meats and cream. Unsaturated fats are classified as monounsaturated or polyunsaturated and may help to reduce LDL cholesterol. Monounsaturated fats are found in olive oil, and the polyunsaturated fats are found in fish or corn oil. Some adolescents manufacture more cholesterol in their liver than others, and this may be due to genetic influences.

Studies have demonstrated that adults in the United States have higher rates of coronary artery disease compared to other countries. When compared to adolescents in other countries, teens in the United States have higher blood cholesterol levels as well as a diet higher in saturated fats. When autopsies have been performed on teens who have suffered premature death, studies have demonstrated changes in their coronary arteries consistent with early coronary artery disease. These changes are related to high levels of LDL cholesterol and low levels of the protective HDL cholesterol. Adolescents with high cholesterol levels, especially LDL cholesterol, are likely to come from families with a higher risk for coronary artery disease as adults. And adolescents with high cholesterol are more likely to have high cholesterol levels as adults although this is not true for all adolescents.

The western lifestyle in itself is a risk factor for elevated cholesterol. The American culture which includes a diet that is high in fat and cholesterol, low in fiber and high in protein is a risk for the development of higher than normal cholesterol. In fact, more than half of all American adults have cholesterol above 200, which is considered the upper range for normal. Other risk factors from our American lifestyle include obesity and our sedentary life. Smoking is also a risk.

Genetics play an important role in determining a teen’s cholesterol level. Genes may influence if one has high or low HDL cholesterol levels. And the family lifestyle and diet will have an important effect on an adolescent’s cholesterol.

There typically are no symptoms for high cholesterol in teens. When symptoms do occur in adults, it is due to the buildup of plaque in the coronary arteries.

The question is who should be screened for high cholesterol. The American Academy of Pediatrics (AAP) has developed guidelines to assist primary care clinicians in determining which adolescents should be screened. Recommendations from the AAP include the following:

• Screen adolescents whose parents or grandparents at or below age fifty-five years had coronary artery disease, suffered a heart attack, symptoms of coronary artery insufficiency or had disease of the blood vessels in the brain.
• Screen adolescents whose parent has cholesterol at 240 or higher.
• Screen adolescents whose parental history is not available.
• Screen adolescents who have other risk factors including obesity, hypertension, diabetes, history of smoking or a diet high in saturated fats.

Screening usually consists of a random cholesterol test. If the adolescent’s cholesterol is higher than 200, then a fasting lipoprotein analysis is usually ordered. In this analysis, the HDL and LDL cholesterol can be measured as well as the triglycerides. If there is a history of premature heart disease in the parents or grandparents, some practitioners do the fasting lipoprotein analysis immediately.

The AAP has published the following values to classify the total and LDL cholesterol levels for adolescents from families with high cholesterol values or premature cardiovascular disease:

HDL cholesterol abnormal is less than 40 Source: Pediatrics February 2006

How is high cholesterol treated?

Most clinicians will obtain several measurements of cholesterol prior to initiating a treatment plan. If a teen has an acceptable LDL level which is less than 110, then the recommendation is to repeat the lipoprotein analysis in five years. Counseling on diet and exercise are important. If the LDL cholesterol is in the borderline range, then the American Heart Association step one diet is recommended, and a repeat lipoprotein analysis may be done in one year. Counseling on risk factors including diet, exercise and smoking is also done. If the LDL cholesterol is high, then a thorough medical screening is indicated for the teen as well as a review of his or her family members. The step one diet, possibly step two diet or medication may also be prescribed.

The step one diet recommends no more than thirty percent nor less than twenty percent of the teen’s daily caloric intake should be from fats. Less than ten percent of the calories should be from saturated fats, ten or less of the calories should be from polyunsaturated fats and no more than 300 mg of cholesterol should be eaten daily. Although attainable, this is not an easy diet for American adolescents to have on a daily basis. The step two diet is even stricter. A dietician should counsel an adolescent who is prescribed this diet. The components of this diet include no more than thirty percent nor less than twenty percent of the teen’s daily caloric intake should be from fats. However, less than 7percent of calories should be from saturated fats, ten percent or less of calories should be from polyunsaturated fat, and there should be no more than 200 mg of cholesterol eaten on a daily basis. Monounsaturated fats, which are found in olive oil, canola oil and avocados make up the difference in fat calories after the polyunsaturated and saturated fat calories, are eaten. Note that it is important for growing adolescents to have at least twenty percent of their daily calories from fats according to these recommendations.

Drug therapy for high cholesterol is recommended in limited circumstances for teenagers. A trial of the step one or step two diet should be attempted for at least six to twelve months. If the LDL cholesterol remains at or above 190, or if the LDL cholesterol is at 160 or more and there is a family history of premature heart disease or if the teen has several risk factors including obesity and hypertension, then medications may be ordered.

Adolescents are usually prescribed bile acid sequestrants and these include cholestyramine or colestipol. These medications bind bile acids in the intestine. Bile is made by the liver using cholesterol as an important component. When these drugs bind with the bile acids in the intestine, the acids are excreted with the stool rather than being absorbed in the body. As a result, the liver must take cholesterol from the bloodstream to produce more bile acids. This results in a lowering of the LDL cholesterol level by fifteen to twenty percent when used with an appropriate diet. Some individuals do develop gas, constipation and heartburn when using bile acid sequestrants. Other drug therapies including the statin medications could be prescribed for adolescents under certain conditions.

All adolescents should strive for a step one diet. This will promote lower cholesterol for the general population. Since exercise will increase HDL cholesterol, all teens should incorporate a regular exercise program as part of their routine. And it is important to have a normal body weight for height. Striving for an appropriate body mass index (BMI) should include a proper diet and exercise program. It is much easier for an adolescent to carry out a step one diet if the entire family is on the same diet.

Related topics:

Body mass index, dieting, exercise, genetic disease, heart disease, high blood pressure, smoking and tobacco, vegetarianism.