What is it
Cholesterol is a white, waxy, fatlike substance. Although we usually think of it as found only in the bloodstream, it is actually present in all tissues in humans and other animals. It is thus present in all foods from animal sources. It is not present in any plants.
Cholesterol is essential to life: among other things, it is used in the outer membranes of cells; as a fatty insulation sheath around nerve fibers; and as a building block for certain hormones.
Despite its importance to life, cholesterol isn’t an essential nutrient you don’t have to consume any to stay healthy. Most of the cholesterol in your bloodstream is manufactured in your body primarily by the liver from the fats, proteins, and carbohydrates you eat.
Just how cholesterol is distributed throughout the body is not entirely clear, but researchers now hypothesize that the mechanism works in this way. The liver puts together packages called lipoproteins, made of proteins, cholesterol, and triglycerides (fats either made by the body or derived directly from foods). Low-density lipoprotein, or LDL, carries cholesterol throughout the system, dropping it off where it can be used for cell metabolism. Cholesterol carried by LDL that is not used, broken down by the liver, or excreted is left to circulate in the bloodstream where it accumulates in the arterial walls. Nodules, called plaques, are eventually formed, decreasing the flow of blood over time a condition known as atherosclerosis and favoring the formation of blood clots. This may ultimately cut off the flow of blood; in the coronary arteries, this leads to a heart attack, and in the cerebral arteries, a stroke.
The liver makes another type of molecular package known as high-density lipoprotein, or HDL. Like the other lipoproteins, HDL is composed of proteins, fats, and cholesterol, but HDL carries less cholesterol than LDL. As it circulates through the bloodstream, HDL seems to have the beneficial capacity to pick up cholesterol and bring it back to the liver for reprocessing or excretion.
In simple terms then, LDL brings cholesterol into the system, so it’s often called “bad” cholesterol, and because HDL clears cholesterol out of the system, it has been dubbed “good” cholesterol. HDL (as well as LDL) is formed only in the body. You can’t eat “good” cholesterol; no type of cholesterol you eat is good for you.
Cholesterol and heart disease
Generally speaking, a high total cholesterol level, along with a high LDL level, is associated with an increased risk of heart disease. Low HDL, defined as 35 milligrams per deciliter (mg/dl) or below, is also considered a risk factor for heart disease. A high HDL level, defined as 60 mg/dl or more, is considered protective against heart disease. (Female sex hormones tend to raise HDL; this may help explain why women are usually protected against atherosclerosis during their childbearing years, when estrogen production is high.)
Experts now believe that to be at low risk for heart disease, adults should reduce their total blood cholesterol levels to less than 200 mg/dl. While there is no magic number a point at which your blood cholesterol level automatically passes from safe to dangerous the risk of heart disease rises continually with increasing levels of blood cholesterol, though it doesn’t rise markedly until levels exceed 200 mg/dl. And the rate of coronary heart disease begins to accelerate rapidly above the 220 mg/dl level. Thus, many researchers believe that cholesterol levels should be as low as possible; well below 200 mg/dl is excellent.
Some experts question whether high blood cholesterol levels cause heart disease in everybody, and certainly your cholesterol level needs to be put in perspective within your total risk scenario for heart disease, based on such factors as age, sex, and health habits like exercise levels and whether you smoke. But there is substantial evidence that, in most cases, the connection between high blood cholesterol levels and heart disease is as incontrovertible as the link between smoking and lung cancer. This connection is strongest in men under 50 years of age. For young women and for everybody over 50, the link is weaker but still significant.
Symptoms
- There are no obvious symptoms for high levels of blood cholesterol, but the problem is linked to other conditions that have recognizable symptoms, including heart disease, stroke, and high blood pressure.
What causes it
A diet rich in cholesterol and even more significantly in saturated fat can increase your blood cholesterol level. (Sources of saturated fat include beef, butter, whole-milk dairy products, dark meat poultry, poultry skin, and coconut, palm, and kernel oils.) Many other factors affect your blood cholesterol level, and some people, no matter how small their fat and cholesterol intake, may continue to have high blood cholesterol levels because of genetic disorders, diabetes, or other metabolic diseases. For most people, though, diet remains the first defense against elevated blood cholesterol.
Other factors that can raise cholesterol levels are excess weight (each pound gained adds to total blood cholesterol) and smoking (which increases total cholesterol and decreases HDL cholesterol).
Before menopause, women tend to have higher HDL levels than men of the same age, and some researchers think that the higher HDL levels (as well as lower LDL) may be linked to estrogen.
What if you do nothing
A high total cholesterol level isn’t likely to decrease significantly unless you make some or all of the lifestyle changes described below, particularly those regarding weight control and diet. Some individuals may also require cholesterol lowering medication to control their cholesterol levels.
Home remedies
The following measures tend to lower total cholesterol and LDL levels, and also tend to raise HDL levels or may at least stabilize HDL while bringing down LDL. (Not everyone responds to these changes, and if your total cholesterol level remains high after several months of adopting these changes, you should consult your doctor about taking cholesterol-lowering drugs)
Lose weight
Not only does excess body fat raise LDL levels and reduce HDL, but it also appears to be an independent risk factor for heart disease. Where the fat accumulates is also important: excess weight around the waist (the so-called apple-shape body) seems to reduce HDL more than weight in the hips and thighs (pear shape).
Cut down on saturated fats
This is the most important dietary step you can take. First, keep your total fat intake at or below 30 percent of your daily calories. Secondly, substitute unsaturated fats for saturated fats. Studies have shown that polyunsaturated fats (such as safflower and com oil) and monounsaturated fats (such as olive oil) help to lower blood cholesterol levels. Monounsaturated fats may help maintain or increase the level of HDL cholesterol as well.
Cut down on dietary cholesterol
It’s estimated that reducing cholesterol intake from food from 500 to 250 milligrams a day will lower total blood cholesterol by an average of 10 milligrams. This response is variable, however; some people have little or no response, and others a far greater one.
Watch out for “trans fats.”
Manufacturers hydrogenate that is, add hydrogen to corn, soybean, and other liquid vegetable oils to make them more stable. This prolongs the shelf life of margarines, crackers, cookies, potato chips, and other foods that contain the semisolid oils. Hydrogenated oils are also often used for deep frying in fast-food restaurants. But hydrogenation alters many of the oils’ unsaturated fatty acids, making them more saturated and changing their structure in other ways that transforms them into trans fatty acids, or simply trans fats. Studies have shown that trans fats act like saturated fats raising total and LDL cholesterol levels and there is some evidence that they lower HDL cholesterol as well.
Nutrition labels are misleading since they don’t specify how much trans fat is in the foods and don’t count it as saturated fat. Hence, trans fats remain invisible on food labels. But if you eat lots of margarine and also many processed foods, cut back, or switch to a tub or liquid “squeeze” margarine, which has fewer trans fatty acids. “Diet” margarines are even better they contain more water and only half the fat of other margarines.
Exercise more
Results of studies have been inconsistent concerning the effect of aerobic exercise or strength-training exercise on total cholesterol and LDL. But the evidence is stronger that an exercise program can help raise HDL, and its effect on lowering the risk of coronary artery disease (CAD) is overwhelming. The exercise doesn’t have to be strenuous walking a mile or two or even gardening several times a week can help.
Consume more soluble fiber
Eat more legumes, oats, fruits, and vegetables such as carrots, split peas, and com. Sweet potatoes, zucchini, and broccoli have some soluble fiber, as do bananas, apples, pears, and oranges. If you regularly eat a high-fiber, low-fat diet that includes a variety of the vegetables and fruits listed above and some oatmeal or oat bran daily, you may see results the next time you have a cholesterol test particularly if the level was previously elevated.
Eat fish instead of meat
According to some studies, the oil in fish polyunsaturated fatty acids called omega-3s—can lower elevated cholesterol. Evidence from other studies disputes this, but substituting fish for meat (or other sources of saturated fat) should significantly lower blood cholesterol. Eating fish is preferable to taking fish oil supplements. Not only is fish one of the best nutrient-rich foods around, but it is unclear whether omega-3s, by themselves in supplements, provide the same health benefits as eating the fish itself
Consider a drink or two a day
A number of studies have shown that moderate alcohol consumption defined as no more than two drinks a day for a man, one drink a day for a woman may boost HDL. The health risks of heavier drinking, however, outweigh the potential benefit for the heart.
Don’t smoke
Smoking increases total cholesterol and reduces HDL. In addition, it is an independent risk factor for heart disease.
Prevention
The same measures that help lower high cholesterol levels can also help prevent cholesterol levels from rising in the first place, so follow the recommendations described above. You should also have your blood cholesterol level tested periodically by your doctor.
