What is cholesterol?
Cholesterol: it worries parents and grandparents the world over (perhaps even yours), but do you know what it is? The first thing to know is that cholesterol is a lipid—a water insoluble substance (fats are also lipids). If you were to hold cholesterol in your hands, you would find it to be a waxy substance. It is in everyone’s bodies, but only 20 percent of our cholesterol is from diet; 80 percent of our cholesterol is produced internally—mainly in the liver—and travels through the bloodstream to where it is needed.
If cholesterol is water insoluble, however, how does it travel through our water-based blood? The answer is lipoproteins, particles comprising cholesterol, proteins, and triglycerides (triglycerides being another type of lipid). Low-density lipoproteins are the “main carrier” of cholesterol in the blood, although high-density lipoproteins (HDL) are also present within the body.
What cholesterol ideally does to the body
Cholesterol is often demonized, but it plays several crucial roles in the body, including: building cell membranes, producing hormones, and aiding in digestion. Additionally, HDL cholesterol helps remove deposits of LDL cholesterol–buildups of which block blood flow.
First, consider cholesterol's role in the membrane of cells. Because of cholesterol’s polarity (i.e. the position of the electric charges within the molecule), lipid layers become curved; cholesterol’s molecular structure affects the fluidity, thickness, and curvature of cell membranes. This structural role is vital for cell function, as the membrane serves as a barrier and a communication hub between the interior of the cell and its external environment.
Secondly, consider the production of hormones. Besides the aforementioned polar hydroxyl group, cholesterol also comprises four hydrocarbon rings—these rings are present in all steroid hormones. Steroids, contrary to what you may have heard, are not just used by some unscrupulous athletes. Steroid hormones include (but are not limited to) the sex hormones, testosterone and estrogen. No cholesterol means no steroids, which in turn affects bone density, mood, and sexual development..
Finally, recall that cholesterol is particularly necessary for the absorption of fat-soluble vitamins. Bile acids are synthesized from cholesterol in the liver; these acids reduce the surface tension of digested food, allowing it to be more readily absorbed. Without cholesterol, vitamins such as A, D, E, and K are difficult or impossible to digest—said vitamins being vital for immune system function, bone formation, eye health, and blood clotting, respectively.
What an imbalance of cholesterol does to the body
As you might surmise, if cholesterol is necessary for many functions, a lack of cholesterol will negatively affect one’s health. Cholesterol is essential for building cell membranes, producing hormones, and aiding in the digestion of fats. When cholesterol levels are too low, these functions can be impaired, leading to potential health problems.
More research is needed on the effects of low cholesterol (the effects of high cholesterol are better understood), however possible links between low cholesterol and diseases such as cancer and depression have been observed. This may be caused by disrupted hormone production; hormones regulate many bodily functions, so disrupting them can have negative knock-on effects. Low cholesterol has also been associated with increased risks of hemorrhagic stroke, which occurs when a weakened blood vessel bursts in the brain.
The nuanced nature of cholesterol is best exemplified by its interactions in the bloodstream; cholesterol levels which are too low or too high can both have detrimental effects, depending on the type of cholesterol in question. If HDL cholesterol levels are too low, it inhibits the removal of LDL cholesterol. In turn, if LDL cholesterol levels are too high, plaques build up in the bloodstream, which blocks blood flow around the body—cardiovascular problems such as heart disease and stroke can soon follow.
Closing thoughts
While high cholesterol levels can increase the risk of heart disease and other health problems, having too little cholesterol in the body can also have negative effects on overall health. It is important to maintain a healthy balance of cholesterol through a balanced diet and lifestyle to support optimal health and well-being.
Cholesterol levels can be influenced by a variety of factors, including genetics and diet. High cholesterol levels, particularly high levels of LDL cholesterol, are a significant risk factor for cardiovascular disease, which is the leading cause of death worldwide.
To manage cholesterol levels, it is important to maintain a healthy lifestyle. This includes eating a balanced diet that is low in saturated and trans fats—as the Mayo Clinic puts it: “cholesterol levels have more to do with the fat you eat, namely saturated and trans fats, than cholesterol.” This means that high-cholesterol foods (such as eggs) are, perhaps counterintuitively, healthier to eat than foods which might have lower cholesterol levels but higher amounts of saturated and trans fats. While in some cases medication may be prescribed to help lower cholesterol levels, check your diet first with a doctor. As the saying goes, you are what you eat.
