Within certain limits, cholesterol is, in fact, an essential substance for the proper functioning of organs: it is a very important component of the plasma membrane that delimits cells and participates in the synthesis of steroid hormones, bile and vitamin D.
Not being able to rely on food intake alone, the human body has evolved in such a way as to be able to develop an effective mechanism for the biosynthesis of cholesterol. This synthesis capacity is developed above all in three organs: the liver, the intestine and the skin.
Every day, the body of an adult produces, to meet the various needs, about 600-1000 mg of endogenous cholesterol.
are, in this sense, the most active organs.
The amount of endogenous cholesterol is accompanied by that taken from the outside, through food, called "Exogenous Cholesterol"; in general, a balanced diet brings from 200 to 300 mg of cholesterol per day.
);Familial hypercholesterolemia is a hereditary disease characterized by a defect in the genes involved in the synthesis of membrane receptors for LDL; in the absence of these receptors, the liver is unable to pick up the IDL and LDL lipoproteins deriving from peripheral lipid metabolism, interpreting the situation as a cholesterol deficiency; as a result, lipid synthesis is enhanced.
Subjects suffering from familial hypercholesterolemia have plasma cholesterol concentrations up to 6 times higher than normal (600-1000 mg / dl); it is therefore not surprising that many of these subjects die before the age of 20 from atherosclerotic phenomena and related diseases.
.The increase in cholesterol levels beyond the norm derives from the combination of an innate genetic predisposition with environmental factors, such as atherogenic diet (high intake of saturated fats, hydrogens and cholesterol), obesity and a sedentary lifestyle.
The typical age of onset of polygenic hypercholesterolemia is adulthood, usually after 30 years.
Importance of a correct diet
Unlike the previous one, this form responds quite well to the diet.
Before resorting to drugs to lower cholesterol, it is therefore important to intervene in the first instance on the diet, possibly associating it with regular physical exercise (after consulting a doctor).
Dietary recommendations are generally based on these points:
- Reduce the total energy intake in overweight subjects;
- Reduce the total fat of the diet to less than 30% of the total energy;
- reduce the intake of saturated fatty acids (food of animal origin) to less than 10% of the total energy; we remember in fact that a diet rich in saturated fats can increase cholesterolemia by 15-25%; this increase is the consequence of the deposition of fats in the liver, from which a greater quantity of Acetyl-CoA available for the hepatic synthesis of cholesterol derives; often underestimated, the reduction of saturated fats in the diet is therefore even more important than the simple reduction of dietary cholesterol;
- Reduce, possibly eliminate, foods rich in hydrogenated oils (present in margarine and in many baked goods);
- Reduce the consumption of carbohydrates with a high glycemic index (particularly sweet foods, such as pastry and some types of fruit);
- Encourage the consumption of oleic acid (present in olive oil) and linoleic acid (present in fish);
- Encourage the use of complex carbohydrates;
- Increase the consumption of fruit (except bananas, figs, grapes, persimmons and dehydrated fruit), vegetables and legumes;
- Moderate the salt intake.
Medicines
Any failure of the diet requires the use of lipid-lowering drugs, which, however, must not be substituted, but associated with it, in order to exploit the synergistic action of the two therapeutic interventions. The most used drugs in the presence of hypercholesterolemia are statins (inhibitors of HMG-CoA reductase) and fibrates (more useful in the presence of high triglycerides). Other drugs commonly used are ezetimibe, niacin and bile acid sequestrants.
For further information: Medicines for High Cholesterol
