What are the causes of high cholesterol?

It might be surprising to know that the human body makes all the cholesterol we need. When a doctor takes a blood test to measure cholesterol levels, the doctor is really measuring the amount of circulating cholesterol in the blood, or the blood cholesterol level. About 85 percent of the blood cholesterol level is endogenous, meaning it is produced by the body. The other 15 percent comes from an external source - the diet.

Your dietary cholesterol comes from meats, poultry, fish, seafood and dairy products. It is possible for some people to eat foods with high levels of cholesterol and still have low blood cholesterol levels. It is just as possible to eat foods low in cholesterol and have high blood cholesterol levels.

So then, why is there so much talk about dietary cholesterol The answer seems obvious: the level of cholesterol already present in the blood can increase with high consumption of cholesterol and saturated fat in the diet. This increase in dietary cholesterol is associated with atherosclerosis - or the build-up of plaques that narrow or block blood vessels. It?s similar to kitchen drain pipes when someone pours chicken fat down the sink. If the heart?s coronary arteries become blocked, a heart attack can occur. A blocked artery also can develop rough edges. This can cause chunks of plaque to break off and travel, obstructing blood vessels at other places in the body. This also can be deadly. A blocked blood vessel in the brain can cause a stroke.

The average American male eats about 360 milligrams of cholesterol a day. Women in America eat an average 220 to 260 milligrams daily. The American Heart Association recommends that we limit average daily cholesterol intake to less than 300 milligrams. People who already have high levels of cholesterol in the blood, obviously, should take in even less.

People develop abnormal cholesterol levels for many reasons including physical inactivity, obesity, age, sex, and a diet high in animal fats. Some inherited genetic disorders also cause the body to overproduce cholesterol and to eliminate it inefficiently.

Cholesterol levels are mainly determined by the interaction of your genetics, diet and lifestyle choices. One of the primary causes for elevated cholesterol in Western cultures is diet. While you cannot alter your genetic code, by maintaining a healthy weight through a personalized eating plan and increasing physical activity you can significantly reduce your cholesterol levels. Lifestyle modification is the cornerstone of any treatment plan to lower cholesterol and reduce your risk of heart attack and stroke.

In particular, a diet rich in saturated fats from red meats, and high fat dairy products (butter, cheese, milk) is most likely to elevate cholesterol levels. Also, so called trans fats or "partially hydrogenated" oils present in many packaged snack foods, bakery products, margarines andfried foods are particularly likely to lead to problems with high cholesterol.

In addition, hormone disorders such as diabetes and underactive thyroid as well as certain medications may elevate cholesterol levels.

The two most common causes of high cholesterol are genetics and environmental factors.  Genetic factors usually cause what is called familial hypercholesteremia. Environmental causes can include poor dietary choices and obesity. There are also other factors that are associated with high cholesterol, and these can include diseases such as diabetes, hypothyroidism, patients on dialysis and patients on medications such as steroids, diuretics or beta-blockers.

Elevated cholesterol levels are usually due to an increased manufacture of cholesterol within the liver rather than an increased dietary intake of cholesterol. However, elevated cholesterol levels are also reflective of dietary and lifestyle factors, such as high saturated fat intake and lack of physical exercise. Elevated cholesterol can also be due to genetic factors.

Poor diet is a leading culprit when it comes to unhealthy cholesterol levels. Eating a diet high in saturated fat and trans fats increases "bad" low-density lipoprotein (LDL) and reduces "good" high-density lipoprotein (HDL) cholesterol. Meats, eggs, and full-fat dairy products are particularly high in saturated fat, and any foods made with hydrogenated vegetable oils contain trans fats.

Too much dietary cholesterol can also affect blood cholesterol levels, although each person absorbs a different amount from his or her food, depending on his or her genetic makeup. Dietary cholesterol is found almost exclusively in foods of animal origin, such as eggs, meats, and dairy.

Inactivity and other lifestyle choices, such as smoking, also contribute to unhealthy cholesterol levels.

Several conditions and diseases can elevate cholesterol levels, too. These include diabetes mellitus, hypothyroidism, hypercholesterolemia, kidney disease, obstructive liver disease, and familial disorders such as familial hyperlipidemia. Only a small portion of high cholesterol cases are a result of these medical conditions.

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Consuming fats that raise your cholesterol is only one of many factors that increase your risk of heart disease, strokes, and dementia. Excessive blood cholesterol is also the result of eating a low-nutrient diet that causes intravascular inflammation and, as a result, heightened cholesterol production due to insufficient fiber, which binds cholesterol in the digestive tract. Your cholesterol level goes up when you don't eat enough vegetables and beans. Saturated fat, and especially trans fat, drives cholesterol higher than simply eating cholesterol does. For example, eggs are high in cholesterol, but eating eggs will not raise your cholesterol as much as eating cheese because cheese is much higher in saturated fat.