From a young age we have been taught that fat is bad - that if you eat plenty of bacon and eggs, it is going to clog up your arteries and cause a heart attack. Then there are the people that have high cholesterol - a group that I belong to. Ever since being diagnosed with high cholesterol in my late 20s, I have been terrified of foods that are high in fat - such as the aforementioned bacon and eggs, butter, fatty fish, etc. I then discovered that there is good and bad cholesterol. The doctor gave me a choice - either take medication or do plenty of exercise. Given that I am an exercise nut, and I do eat healthily, I took the second option, but every time my cholesterol was checked, the bad cholesterol (LDL) always came out above the maximum level. So let's go into a little more depth on this.
What is cholesterol? It is a lipid and is synthesized by every cell in our body. That means that every cell in our body makes cholesterol. Cholesterol is necessary to create cells. When you think of cells, you often think of these two-dimensional cutouts. In reality, they are three-dimensional and they are fluid, and what gives them their fluidity are their membranes, and it is the cholesterol within those membranes that provide this fluidity. Without any cholesterol, there would be no cells, and without cells, we would not exist. Cells are the basic building blocks of all living organisms, including the human body. They play a crucial role in carrying out all the necessary functions of the body. They provide the structural support needed for organs and tissues to maintain their shape and function properly. Cells generate energy through cellular respiration, which converts glucose into ATP (adenosine triphosphate), the primary source of energy for the body. They also transport molecules such as nutrients, oxygen, and waste products throughout the body to ensure that all cells receive the necessary nutrients and remove waste products. Cells also play an essential role in the body's immune system, fighting off pathogens that can cause disease and infection. Finally, cells communicate with one another through chemical signals, allowing the body to coordinate its various functions and respond to changes in the environment.
Now that we know how important cells are for human life, it is also worthwhile looking at the other functions cholesterol plays in our bodies. Cholesterol is a precursor to several hormones, including estrogen, testosterone, and cortisol. These hormones play important roles in regulating a wide range of bodily functions, from sexual development to stress response. Cholesterol is also necessary for the production of vitamin D, which is essential for healthy bones, muscles, and immune function. It is a key component of bile, a substance produced by the liver that helps to digest fats in the small intestine.
Not all the cells in the body have enough cholesterol which means it needs to be transported to where it is needed. There are certain cells that are net exporters of cholesterol such as the liver. As a general rule, the liver makes more cholesterol than it needs whereas there are parts that are net importers because they need additional cholesterol, especially during times of high stress. This creates a bit of a problem because the main channel we use to transport things back and forth is the circulatory system. It is not the only system (we also have the lymphatic system) but the circulatory system is what we tend to use the most. There are lots of things that we transport without much difficulty through the circulatory system such as glucose and electrolytes because they are water-soluble. The circulatory system is made up of plasma and proteins (your blood). Cholesterol is a lipid and it is not water-soluble. It is hydrophobic and it cannot move in water. For example, if you pour olive oil into a glass of water you will quickly see how they repel each other. So this creates a problem. We have this essential thing in our body. Transportation for this thing is essential for our life but the system we have repels it. The solution is to create a vehicle in which we can transport this cholesterol and that vehicle is called a lipoprotein. As the name suggests it is part lipid and part protein. It is engineered in a way that the lipid part is on the inside while the protein part is on the outside, and protein is water soluble. This is the perfect transporter because it can be stored inside and transported to where it needs to go.
These lipoproteins are found in the blood and are classified based on their density which reflects the proportion of protein to lipid in the complex. There are four major classes of lipoproteins, but for the purpose of this blog, we will only focus on the two most famous- low-density lipoproteins (LDL) and high-density lipoproteins (HDL).
LDL is often referred to as bad cholesterol because it was believed that high levels of LDL in the blood can contribute to the buildup of plaque in the arteries which could increase the risk of heart disease and stroke. HDL is referred to as good cholesterol. They are smaller and denser than LDLs, and they have antioxidant and anti-inflammatory properties that may help against the development of heart disease.
There is an assumption that cholesterol causes heart disease. Scientists are now discovering that the greatest cause of heart disease is inflammation, which can lead to insulin resistance and/or oxidative stress. There is a very strong correlation between cardiovascular disease and these three things. On the other hand, there is a very weak correlation between cardiovascular disease and cholesterol. There is no difference between the cholesterol in LDL and the cholesterol in HDL. This means there is no such thing as good and bad cholesterol - that is a myth.