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What is cholesterol?
Cholesterol is a steroid having a polycyclic structure called "cyclopentanoperidrofenantrene"; it is white in color and has a consistency similar to that of wax. It is produced only by organisms of animal origin that could not survive without it; the plants produce and contain other structurally similar lipid substances, called phytosterols.
The human body autonomously synthesizes most of the necessary cholesterol - about 70% - completing the requirement through nutrition - the remaining 30%. Dietary sources of cholesterol are purely of animal origin.
A poor diet, obesity, a sedentary lifestyle and a family genetic predisposition can however induce the abnormal increase in cholesterol in the blood. This increase is undesirable only when it concerns the "bad cholesterol" LDL - which logically also affects the total - consequently increasing the cardiovascular risk. We will go deeper into these topics in other dedicated articles. Instead, we will focus exclusively on the functions of cholesterol in the body.
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Cholesterol functions
The functions of cholesterol are different and all fundamental to organic homeostasis:
- Structural: cholesterol is an essential component of animal eukaryotic cell membranes. Its presence reduces its fluidity and increases its stability.
- Hormonal precursor: starting from cholesterol it is possible to synthesize hormones and para-hormones such as aldosterone, cortisone, testosterone, estradiol and vitamin D3.
- Emulsifying and pro-digestive: a good part of the hepatic cholesterol production is used in the synthesis of bile, a digestive liquid contained in the gallbladder then secreted in the small intestine through the cystic duct and the common bile duct; chemically, bile is called a "suspension" and the alteration of its components can cause its separation with the relative formation of sediment - also called mud / sludge - and, at worst, gall stones.
- Essential for embryonic development: the alteration of cholesterol biosynthesis is associated with fetal malformations.
- Essential in cellular metabolism: cholesterol is an important component for maintaining cellular functions, to the point that its absence would preclude its growth and differentiation.
- Synergic-regulator in the transmission of messengers: together with the channels and receptors of protein origin, cholesterol also intervenes in trans-membrane molecular transmission processes, more precisely allowing the formation of transport vesicles.
Considerations
What you need to know about cholesterol
In light of the aforementioned, it is clear that the functions of cholesterol, besides being necessary for maintaining good health, are essential for life itself. It is however essential to remember that, except for pathological changes, the endogenous production of cholesterol is on average able to comply with the physiological needs of the human organism. Moreover, any balanced diet includes the intake of foods of animal origin - meat, offal, fish, eggs, milk and derivatives. In this regard the dietary recommendations suggest not to exceed 300 mg / day of exogenous cholesterol (dietetic) for healthy people, and 200 mg / day for people suffering from hypercholesterolemia or with a higher cardio vascular risk. Compared to the past, today we are aware that the amount of cholesterol in food, taken individually, is not necessarily related to the increase in cholesterolemia; this is because as dietary intake increases, endogenous synthesis decreases. However, many other dietary factors compromise this balance - above all the contribution of saturated, hydrogenated and trans-metabolic fats - for example a bad glucose metabolism and the presence of type 2 diabetes mellitus - of body composition - entity of the lean and fat mass - and behavioral - physical inactivity, sports, etc. - and obviously genetic - familial hypercholesterolemia.
