Cholesterol: Basic Facts
The word ‘cholesterol’ is often linked with foods such as pastries, fried items and pizzas which are said to be fatty foods. But the reality is that 75% of the cholesterol that circulates in our blood is made by the liver and the remaining 25% only is due to the food that we eat. So, cholesterol is a type of fat (lipid) in our body. Our body makes all the required cholesterol necessary for the cells to make hormones, vitamin D and substances that help in digesting food and the rest that we accumulate from the food we eat is excess cholesterol. Lipoproteins, molecules made of proteins and fat, aid in carrying cholesterol through the blood and are of two types: low-density lipoproteins (LDL) and high-density lipoproteins (HDL). LDL cholesterol is the ‘bad’ cholesterol which increases the risk of heart disease and stroke while HDL cholesterol is the ‘good’ cholesterol which lowers the chance of diseases as cholesterol is carried back to the liver where it is expelled out from our body.
High blood cholesterol, also known as hyperlipidemia or hypercholesterolemia, is characterized by too much of cholesterol in the blood which can lead to coronary heart disease. High levels of cholesterol can lead to buildup of plaque inside arteries, a condition called atherosclerosis. This condition narrows the space for blood flow and hence provokes heart disease. There are no symptoms which can reveal abnormal levels of cholesterol and blood test is the only option available to do so. It is advisable to get a lipid profile test done once every five years if you are aged 20 or above.
Total cholesterol measures total cholesterol content in our blood: LDL, HDL and VLDL (very low density lipoprotein, a precursor of LDL). A total cholesterol score under 200 is said to be healthy and safe. Triglyceride is another form of fat in our blood which can raise the risk of heart disease. LDL levels of less than 100 mg/dl and HDL levels of 60mg/dl and more are desirable for decreased risk of heart attack.
Cholesterol in Children
It is a pity that cholesterol can start accumulating right from childhood and can clog the arteries. Doctors always recommend a healthy diet and meal plan to be inculcated in children right from 2 years of age. This reduces the chance of high cholesterol levels. Ideal total cholesterol should be below 170 mg/dl in people aged between 2 and 19 years.
Genetic Hyperlipidemias: Classification and Diagnosis
Several forms of hyperlipidemia have strong genetic components and are discussed below.
Familial hypercholesterolemia is a disorder seen worldwide and passed down right through families. LDL cholesterol levels are very high here and defects in the LDL receptor gene cause FH. LDL levels range from 190 mg/dl to 400 mg/dl in these patients. Symptoms of FH include xanthomas (fatty skin deposits) in hands, eyelids, ankles and knees, chest pain and sudden stroke-like symptoms. Treatment aims at reducing the risk of atherosclerotic heart disease. Lifestyle changes are suggested by doctors in the form of physical activity and healthy low-fat diet. Aggressive drug therapy is introduced if these lifestyle modifications are not favourable.
Polygenic Familial Hypercholesterolemia
Polygenic familial hypercholesterolemia is due to multiple gene defects. The diagnosis is based on two or more family members have LDL cholesterol levels above the 90th percentile without tendon xanthomas. Treatment includes therapeutic lifestyle changes (TLCs) with cholesterol-lowering drugs.
Familial Combined Hyperlipidemia
Familial combined hyperlipidemia (FCHL) is the most common genetic disorder and can cause early heart attack. In FCHL two or more family members have serum LDL cholesterol or triglyceride levels above the 90th percentile. Again lifestyle modifications are primary treatment goals. If this does not work positively other treatment options like TLCs, diabetes control, weight reduction and medication may be suggested.
Familial Dysbetalipoproteinemia is usually rare. Genetic defect resulting in large lipoprotein particles containing both cholesterol and triglycerides causes this condition. Total cholesterol levels range between 300-600 mg/dl and triglyceride levels range from 400-800 mg/dl. Hypothyroidism, obesity and diabetes can further aggravate this condition. This disease is usually related to defects in the gene for apo E. Treatment includes weight reduction, control of hyperglycemia and diabetes along with dietary modifications to lower saturated fat and cholesterol levels.
High Blood Cholesterol-Causes
Multiple factors contribute to increased cholesterol levels as given below:
- Diet: A diet rich in saturated fats, trans fat and cholesterol can elevate cholesterol levels. Examples of such foods include egg yolk, butter, cheese, milk and meat.
- Weight and physical activity: Absence of physical activity increases you weight. Being overweight raises LDL and total cholesterol levels and decreases HDL levels.
- Age and gender: Cholesterol levels rise in both men and women as they age. Until menopause women have higher levels of HDL and lower total cholesterol levels. But after 55 years, LDL levels begin to rise in women and become higher than men.
Cigarette smoking, low HDL levels, increased bold pressure, family history and age (men aged 45 and above, women aged 55 and above) are major risk factors that affect LDL levels.
High blood cholesterol levels can be treated with both therapeutic lifestyle changes (TLC) and medicines.
Therapeutic Lifestyle Changes
TLC is generally a three-step process which includes weight management, diet and physical activity. The duration for medical nutrition therapy is generally between 3 to 6 months. TLC diet is followed for 6 weeks firstly. During the second visit, LDL levels are checked upon and therapy is intensified as needed. Supplements such as plant sterols, stanols, fiber and soy are briefed upon to the patient at this juncture. At the third visit metabolic syndrome treatment begins if LDL levels still do not improve or reach the specified target.
TLC diet mainly concentrates on lowering saturated fats (must be < 7% of total calories) which is extensively present in meat, chocolates, dairy products and deep-fried foods. Replace this with monounsaturated fatty acids (MUFA) as these can constitute upto 20% of total calories. Polyunsaturated fatty acids (PUFAs) can make up 10% of the total calories and give you the same effect as MUFAs in lowering LDL levels and triglyceride levels. Avoid trans-fat (cookies, packaged snacks and crackers) keeping it to a minimum of 1% of total calories.
Dietary cholesterol plays a key role in increasing total cholesterol and LDL levels but to a lesser extent than SFAs. TLC diet suggests no more than 200 mg of cholesterol each day. Take at least 6 to 10 grams of soluble fiber with the recommended five or more servings of fruits and veggies and six or more servings of grains. Also protein intake of approximately 15% of total calories in any form as in soy proteins (tofu, soy butter and soy nuts) may decrease LDL levels. Stanols and sterols isolated from soybean oils or pine tree oil are said to lower blood cholesterol levels and can be consumed between 2 to 3 g/day. Carbohydrates are highly recommended and must constitute 50% to 60% of the total calories consumed.
What to Eat and What Not to Eat
Fill your plate with ample fruits, vegetables, legumes and whole grains. Make it a point to include fish in your meals at least twice a week. Fishes such as salmon, tuna and mackerel are rich sources of omega-3 fatty acids. Limit your egg yolk intake to 2 servings weekly and also reduce your consumption of sweets, snacks and fast foods in particular. Avoid alcohol consumption and minimize sodium intake.
Losing weight if you are obese or overweight can help in reducing LDL levels. Especially if you have a large waist measurement (more than 40 inches for men and 35 inches for women) it is mandatory to take vigorous action to reduce weight.
Involve yourself in some form of exercise for at least 30 minutes on all possible days. This helps to increase HDL levels and lower LDL cholesterol and triglyceride levels.
Along with the TLC program discussed above certain medications may be required in few cases to keep cholesterol level in check. Few common drugs prescribed are statins, nicotinic acid, bile acid sequestrants and cholesterol absorption inhibitors.