Everyone worries about their cholesterol levels and the causes of high cholesterol, but the truth is that high cholesterol won't kill you. Heart disease will.
The problem is that heart disease and cholesterol are intrinsically linked, with one contributing to another.
(If you want to go straight to the list of Foods That Help Lower Cholesterol click on the link.)
On this page you'll find the answers to these questions:
The common misconception about cholesterol is that it's something bad and needs to be avoided at all times. The truth is that cholesterol is an essential part of every cell structure and is needed for proper brain and nerve function. Without cholesterol we wouldn't be able to live.
It's so important that the body actually manufactures cholesterol in the liver and transports it through the bloodstream to sites where it's needed.
It's a fatty substance and as such doesn't mix very well with blood, because blood is mainly water. So in order to be carried around the blood it needs to latch on to molecules called lipoproteins.
Low-density lipoproteins (or LDLs) are the major transporters of cholesterol in the bloodstream and, because LDLs seem to encourage the deposit of cholesterol in the arteries, it's known as "bad cholesterol".
High density lipoproteins (or HDLs), on the other hand, are considered to be "good cholesterol" because they carry unneeded cholesterol away from the cells and back to the liver, where it's broken down for removal from the body.
If everything is functioning as it should, this system remains in balance.
However, if there is too much cholesterol for the HDLs to pick up promptly, or if there aren't enough HDLs to do the job, cholesterol can form plaque that stick to artery walls and may eventually cause heart disease. (Read more on heart disease by clicking here)
Healthy levels of total serum (or blood) cholesterol are between 190 and 210 mg/dl or 4.9 and 5.4 mmol/l. (Some countries, including the UK, measure cholesterol in mmol/l - millimoles per litre - while others, including the US, use mg/dl - milligrams per decilitre.) Variations either side correlate with increasing rates of disease.
Apart from the total level of cholesterol, it's also important the amount of HDL present in the blood. For men it should be 45 to 50 mg/dl and for women 50 to 60 mg/dl. Higher levels may be protective against heart disease, but levels under 35 are considered risky.
Triglycerides are the most common dietary saturated fats. In fact, they make up approximately 95% of all ingested fats.
They too are transported by LDL and HDL molecules in the blood and if in excess can cause a lot of damage to the arteries. Levels should be less than 150 mg/dl.
Interestingly, apart from high intake of saturated fats in our diet, another cause of elevated triglycerides can be high intake of sugar and refined carbohydrates.
These, in fact, elevate insulin levels, which in turn, are associated with increased cholesterol, triglycerides, blood pressure and risk of death from cardiovascular disease.
As we've seen, cholesterol is so important to the body that the liver has the job to is synthesize it and only 20-25% comes from dietary sources.
Dietary sources of cholesterol are saturated fats from animal origin, such as lard, butter, cheese, beef, pork and poultry, dairy products, and margarine.
Under normal circumstances, if dietary intake is high, there is a corresponding reduction of cholesterol synthesis by the liver. So for most individuals, the amount of cholesterol consumed is unlikely to result in an elevated level of cholesterol in the blood. But that it's not always the case.
Unquestionably, eating animal fat boosts bad LDL cholesterol in most people to varying degrees and cutting out such fat usually lowers LDL cholesterol.
Other types of fat, such as monounsaturated - as in olive oil - and polyunsaturated - as in omega-3 fatty acids - don't have the same effect, in fact lower it.
Other factors such as your genetic makeup can affect your cholesterol levels, but in the main the consumption of foods high in cholesterol and/or saturated fat increases cholesterol levels, while a vegetarian diet, regular exercise and the nutrients niacin and vitamin C may lower cholesterol.
When there is excessive LDL in the blood, it increases the possibility of a build up of plaque on artery walls.
When this happens, the arteries become narrow and the amount of oxygen and nutrients that can pass through them decreases.
The process continues slowly and silently, taking decades to manifest discernible symptoms. One is angina pectoris, or chest pain.
When a coronary artery is completely blocked, often by a blood clot, the part of the heart that receives blood from that artery dies. The result is a sudden, often deadly, myocardial infarction—better known as a heart attack.
Even partial blockage of a coronary artery can lead to death of heart tissue, which may not be manifest by pronounced physical discomfort.
Blockage of arteries in other parts of the body can cause strokes, gangrene of the legs, and even loss of kidney function.
Not necessarily. The problem arises when the cholesterol we do have circulating in our bloodstream is oxidized by free radicals, molecules produced as a by-product of energy production. The LDL then turns rancid, much as unrefrigerated butter does.
In this altered form, cholesterol gets sticky and more likely to attach itself to the artery walls, where it's quickly gobbled up by cells of the immune system called macroghages.
Stuffed with fat globules, these macrophages enlarge into dreaded "foam cells", which insinuate themselves into artery walls, beginning the gradual narrowing of your coronary artery known as atherosclerosis. (Read more on atherosclerosis by clicking here).
If you can prevent this toxic transformation, your LDL cholesterol may remain relatively harmless.
So the issue is not just how much LDL cholesterol your blood contains, but how much of it is "toxic oxidized LDL" capable of clogging your arteries.
So some researchers now believe that cholesterol is not so dangerous to arteries unless it's converted into a toxic form by oxygen free radicals in your blood.
Hence the importance of a diet very high in antioxidants (read about them by clicking here).
Can eating foods such as eggs, liver, caviar and some seafood - all very rich in cholesterol - be one of the causes of high cholesterol?
The truth is that although high cholesterol foods are a minor cause of high blood cholesterol, saturated animal fat is the real enemy - four times more potent in boosting blood cholesterol levels.
In fact, some studies show that a diet rich in cholesterol-laden eggs raises blood cholesterol in only two out of five people and only slightly. In most people, production of cholesterol by the liver is simply turned down.
Still, overdosing on cholesterol-rich foods is not a good idea for other reasons. Splurging on high-cholesterol foods can promote heart disease by stimulating the blood to form clots and that's not good.
On the other hand, fanatically avoiding cholesterol-rich foods altogether could also be hazardous, because you could develop a choline deficiency, leading to liver damage.
Choline is a B-complex vitamin, concentrated in high-cholesterol foods, such as eggs and liver and is essential for the good functioning of the liver.
A lack of choline in the diet could also impair memory and concentration. Choline converts to a brain-cell transmitter, acetylcholine; low levels have been linked to poor memory and Alzheimer's disease.
So the bottom line is, don't go overboard with eggs and cholesterol-rich foods, but you don't need to avoid them altogether either.
Apparently yes. Increasing evidence seems to show that very low levels of cholesterol - under 160 mg/dl - may be dangerous.
Some studies indicate that people with low levels of cholesterol have indeed less heart disease but are twice as likely to have a bleeding stroke, to die of obstructive lung disease or commit suicide, are three times as likely to have liver cancer and five times as apt to die of alcoholism.
How is that possible? Nobody knows for certain, but in recent years clues have emerged hinting that very low cholesterol levels may not be safe.
Brain hemorrhages in which a weakened vessel "blows out", causing a bleeding stroke, appear to be a particular danger, possibly because fragile membranes that cover brain cells need a minimum level of cholesterol to function properly.
There is also evidence that low cholesterol may somehow induce depression, possibly because it may somehow lessen concentration of the brain chemical serotonin, leading to increased depression and aggression.
BOTTOM LINE: What you eat affects the amount of cholesterol that is circulating in your body as well as what happens to it, whether it gets oxidized or not.
For a list of foods that can help lower cholesterol as well as prevent oxidation click on one of these pages:
Antarctic Krill Oil - is even more powerful than fish oil in preventing and treating heart disease