The Good and The Bad: The Truth About Cholesterol
Next to fat, cholesterol has received a notoriously bad reputation. Fats, particularly trans-fats and some saturated fats, have been linked with high cholesterol; and high cholesterol has been linked with heart disease and other serious, and sometimes fatal, health problems.
Nevertheless, like with both adipose tissue and dietary fat, your body needs a certain level of cholesterol in order to function. Many people may have heard the term “good” cholesterol and “bad” cholesterol. This isn’t entirely accurate since there is no such thing as “bad” cholesterol; your body needs all forms of it. The problem is with the quantity. Too much cholesterol, like too much sugar and too much fat, are what make cholesterol a growing health concern.
What is cholesterol?
Cholesterol is a fat-like (lipid) and waxy compound mainly manufactured by the body in the liver and other cells, though it can also be found in foods such as dairy, eggs, and meat.
It is carried around the body in the blood attached to a protein. These groups of soluble proteins that combine with and transport fat are known as lipoproteins.
Almost every cell produces cholesterol all the time, but most of the body’s cholesterol is produced in the liver and circulated in the blood. Like all lipids, cholesterol is insoluble in water, so it must be transported in lipoproteins.
Lipoproteins are particles made of fat (lipids) and proteins. They not only transport cholesterol, but are also carriers of triglyceride (a type of fat in the blood), phospholipids, and protein. All lipoproteins contain all of these substances.
The type of lipoproteins is determined by the proportion of these substances, the type of protein, and how much protein there is in relation to fat content (density). The more lipid the lipoprotein contains relative to protein, the densest substance in the molecule, means it has a lower density. As the density increases, the size of the particles generally decreases.
When people mention “cholesterol,” they are usually referring to the amount of lipoproteins in the blood.
What is cholesterol used for?
Cholesterol performs a number of important functions in the body. Every cell needs cholesterol to form its protective membrane. It is an important constituent in the membrane, where it helps provide structure and firmness. This helps the tissues in the body to withstand the high pressure and turbulence of blood flow. This cholesterol also plays a role in facilitating cell signalling.
Cholesterol is used in the creation of steroid hormones, including testosterone, estrogen, progesterone, pregnenolone, androsterone, and aldosterone and in the production of bile acids. Bile acids are needed to digest and absorb fats and fat-soluble vitamins. After it is used, bile gets reabsorbed into the digestive system and returned to the liver for recycling.
Without cholesterol, our body would not be able to digest and absorb essential vitamins, including vitamins A, D, K, and E. Naturally produced vitamin D is also derived from cholesterol.
In addition, cholesterol is required in the proper function and growth of the brain, skin, and other organs and is vital for neurological function and memory formation.
It has four main functions which include contributing to the structure of cell walls, making up the digestive bile acids in the intestine, assists the body in producing vitamin D, and enable the body to make certain hormones.
What are the different types of cholesterol?
Each type of lipoprotein is broken down and excreted in a slightly different way. There are five main classes of lipoproteins: chylomicrons, very low density lipoproteins (VLDL), low density lipoproteins (LDL), intermediate density lipoproteins (IDL), and high density lipoproteins (HDL). The three more commonly known lipoproteins are VLDL, LDL, and HDL.
There are two main types of lipoproteins, depending on the amount of protein in relation to fat. They are: low-density lipoprotein (LDL) or “bad” cholesterol, and high-density lipoprotein (HDL) or “good” cholesterol.
Low-density lipoproteins, or “bad” cholesterol
LDL contains more cholesterol in relation to protein. LDL particles take this cholesterol to parts of the body. If there is too much, the particles can deposit the cholesterol into the arteries, causing blockages.
Low-density lipoproteins, more commonly known as LDL or “bad” cholesterol, delivers cholesterol to cells. LDL is remodelled in the liver from VLDL (very low density lipoproteins) that are stripped of triacylglycerol and become more dense.
VLDL lipoproteins are similar to LDL. They contain mostly fats and little protein, and transport triglycerides. Triglycerides are fats found in the body that have been converted from excess calories, alcohol, or sugar.
Once the cholesterol is delivered to the cells, it is used in the membranes, for synthesis of steroid hormones and for immune response. When the body experiences injury, immune cells are released. These cells are made primarily of cholesterol and fats. “When the cells are damaged, they require cholesterol and fats to repair themselves” (1).
Cholesterol also acts as an antioxidant by neutralizing free radicals. Free radicals are highly reactive molecules used by immune cells to destroy microbes and toxins.
Furthermore, if our tissues are cut or small arteries, veins, and capillaries get damaged, such as if we have surgery, the liver receives a strong signal to produce more LDL cholesterol to clean and heal the wounds. More LDL cholesterol is also produced when we have an infection. It also plays an important role in stress hormone production. This means that the body will produce more LDL cholesterol when our bodies are under stress. When the wounds heal or our body is no longer under stress, the cholesterol is no longer needed. It is carried back to the liver in high density lipoproteins.
The reason for LDL’s “bad” reputation is due to the fact that elevated levels can lead to buildup of cholesterol in the arteries. This cholesterol can combine with fat, calcium, and other substances to form plaque. “When there is excess cholesterol, LDL and VLDL carry cholesterol into blood vessels – where they can stick to the walls of your arteries, forming plaques/deposits which can block your arteries” (2).
The buildup of plaque is known as atherosclerosis. As the plaque builds up, the arteries begin to harden and narrow. Blood flow can be restricted or become clotted and eventually lead to heart disease, heart attack, and stroke. The higher the level of LDL cholesterol, the higher the risk of developing plaque.
High-density lipoproteins, or “good” cholesterol
High density lipoproteins, more commonly known as HDL or “good” cholesterol, has more protein in relation to cholesterol. It takes up excess cholesterol from cells and tissues and takes it back to the liver, where it is secreted into bile, converted into bile salts, or broken down and removed from the body.
The HDLs collect “stray” or unused LDLs. These lipoproteins can enter and exit the artery wall without causing damage, unlike LDL particles, and also carry damaging particles called oxysterols from the artery wall back to the liver in a process called reverse cholesterol transport (3).
The higher the level of HDL cholesterol, the lower the risk of getting heart disease since HDL helps reduce plaque buildup in the arteries. HDL has also been shown to have anti-inflammatory properties.
It is easy to see how HDL cholesterol is considered to be “good,” but, once one understands the importance of all cholesterol, whether in the form of LDL and HDL, one knows that LDL is not inherently “bad.”
What influences the body’s cholesterol levels?
Our body’s overall level of cholesterol can fluctuate for a variety of reasons. One of the causes is diet. About 70% to 80% of our cholesterol is produced by the body, and the other 20% to 30% comes from food.
Plants are considered to have no cholesterol, since they do not contain animal cholesterol. They contain another form of plant cholesterol that is not absorbed by the body.
We do not need to eat cholesterol, however, in order to make sure we get enough. Our body produces all that it needs. When we consume dietary cholesterol in animal foods, our bodies are designed to absorb a small amount – only what we need – and slow down its own production.
However, some people may take in too much and their body may not limit production. If you have high cholesterol, then it is recommended to limit intake of cholesterol from food because it means your body is having difficulty regulating its LDL and HDL levels.
It is the other foods we consume, the carbohydrates, fats, and proteins, that play a more significant role in cholesterol production. When carbohydrates, fats, and proteins are broken down, they release carbon, which the liver turns into cholesterol.
Carbohydrates, particularly refined sugars and starches, cause a spike, or rapid rise, of blood insulin. When this happens, the body is signalled to make more cholesterol, even if it doesn’t need it. One reason for this is due to the fact that insulin can affect tissue and the accumulation of fat; and fat can cause inflammation. The body produces more cholesterol in response.
Obesity, for a similar reason, also causes a rise in LDL cholesterol. Trans and some saturated fats have also been shown to increase production of LDL cholesterol, as well as cause other health problems. Other factors that affect cholesterol levels include aging, health disorders (such as diabetes and familial hypercholesterolemia), drugs, and lifestyle habits, such as smoking, activity level, and being overweight.
Blood tests are often used to measure the levels of LDL and HDL cholesterol. They are more of an estimate than an exact measurement.
Higher levels of LDL have been associated with a higher risk of heart disease, while lower levels indicate a reduced risk. In the case of HDL, higher levels have been associated with reduced risk of heart disease, while lower levels indicate a higher risk.
High levels of cholesterol mainly become a problem when there is a higher level of LDL in proportion to HDL. Lower levels of HDL mean that excess LDL cannot be removed from the body. Many people choose to take statin drugs to reduce the level of LDL cholesterol.
However, statin drugs work by stopping your body from producing cholesterol. The production of cholesterol is vital. Your overall health depends on your body’s ability to regulate cholesterol and react to different situations, such as injury or illness. By disrupting your body’s natural process, you can prevent your body from adapting and healing.
How can you naturally lower cholesterol levels?
Instead, there are other steps you can take that can significantly impact your cholesterol production and function.
Exercising a minimum of 30 minutes a day has been shown to help raise HDL cholesterol. It also helps you lose weight. Excess weight increases the level of LDL cholesterol, so losing the weight can help reduce those cholesterol levels.
Since refined sugars and starches, processed foods, and trans and saturated fats (particularly from animal sources) have been linked with higher levels of LDL cholesterol, it is recommended to eliminate or reduce those types of foods from your diet.
“There are literally hundreds of respected scientific studies that demonstrate that as animal products increase in a population’s diet, cholesterol levels soar and the occurrence of heart disease increases (4).
Healthier fats, such as omega-3 fatty acids, don’t affect LDL cholesterol. Instead, they help reduce triglycerides, lower blood pressure, and increase HDL cholesterol.
Both types of dietary fibre, soluble and insoluble, are good for the body, but soluble fibre has been shown to act as a “sponge” by “mopping up” cholesterol in the intestines. Avocados in particular have been shown to have a high concentration of unsaturated fats and fibre that helps lower LDL cholesterol and increase HDL cholesterol.
Smoking has been shown to cause injury to blood vessel walls and lower the level of HDL cholesterol, so it is recommended to stop.
Takeaway
High cholesterol is one of the most common health problems, and one of the most preventable and reversible. Because of the adverse health issues associated with high cholesterol, particularly LDL, people have deemed it as an enemy to the body. They take medications and search for an instant “cure” to remove it.
But it doesn’t need “removed,” nor is it inherently “bad.” It is a natural, vital component of the human body and is necessary in being healthy. Instead of working against cholesterol, we must work with it. By taking the right steps, we can not only lower our overall LDL levels, but help our body use it properly. It is a key component of many essential processes and we want it to function as it should.
We can help create a healthy balance of LDL and HDL cholesterol. Just as with many health-related issues, the steps toward achieving health and proper function are deceptively simple; it comes down to exercising, reducing or eliminating animal products from our diet, and eating more leafy green vegetables and whole, unprocessed foods.
Results are rarely seen instantly, but if we continue to eat right and live actively, we will begin to feel and see the difference. Before our bodies can help us in being healthy, we must first help it by making the right choices, one day at a time.