High cholesterol: causes, symptoms and treatment

Cholesterol is a constituent of the membranes that surround cells. It is essential for the production of hormones produced by the genital and adrenal glands. Cholesterol regulation depends on genetic and lifestyle factors. When the level of "bad cholesterol" is too high, it becomes harmful to health. The doctor will then suggest a diet and/or medication to lower this rate. 

What is cholesterol? 

Essential to life, cholesterol is a constituent of the membranes that surround cells . It is also essential for the production of hormones produced by the genital and adrenal glands.

However, the excess of cholesterol (and other lipids) in the blood leads to the formation of plaques on the walls of the arteries : this is atherosclerosis .

In the human body, cholesterol has two origins :

• 70-75% comes from the  liver ;
• 25-30% of food .

• The international unit of measurement for total cholesterol is the millimole per liter or mmol/L. Normal total cholesterol (TC) levels are:

  • Before 30 years : 1.50 to 2.0 g/L ( 4 to 5.2 mmol/L );
  • After 30 years : 2 to 2.5 g/L ( 5.2 to 6.4 mmol/L )

  Read also: the lipid profile in our "medical analysis" section.

• Mechanisms of cholesterol

  In the blood, circulating lipids (fats), including cholesterol, are not soluble in water. They are therefore "carried" by proteins which are soluble. These carrier proteins are called lipoproteins. 

  Classically, three types of lipoproteins are distinguished :

  • Low Density Lipoproteins or LDL , of light density;
  • Very Low Density Lipoproteins or VLDL , of very low density;
  • High Density Lipoproteins or HDL , high density.

  The "bad" cholesterol

  LDL (bad cholesterol) takes cholesterol from the liver and carries it around the body . This cholesterol tends to deposit in the arteries and block them. This is the "bad" cholesterol .

  The "good" cholesterol

  The HDLs pick up the cholesterol deposited in the vessels and bring it back to the liver . This is the "good" cholesterol. Following a blood test, it is determined which part of the cholesterol is carried by the HDLs and which part is carried by the LDLs.

  The  normal level of HDL-cholesterol (the "good" cholesterol) is:

  • Male: 0.4 to 0.65 g/L or 1.0 to 1.65 mmol/L ;
  • Female: 0.5 to 0.8 g/L or 1.3 to 2.0 mmol/L .

  This rate varies according to diet, lifestyle, taking certain medications .

  In the event of a diet rich in animal fats and therefore in cholesterol, the LDLs multiply . The overall blood cholesterol level increases. Heavy carriers (HDL) are overwhelmed and can no longer clean up. The fat then deposits on the atheroma plaques.

  Below 0.35 g/l or 0.9 mmol/L (measured several times) there is a cardiovascular risk. If the Total Cholesterol/HDL ratio > 5: the relative coronary risk is multiplied by 20.  The total cholesterol/HDL-cholesterol ratio must be :

  • Less than 5 in men ;
  • Less than 4.4 in women .

  The danger comes from excess LDL-cholesterol. The other fraction, HDL-cholesterol, on the contrary has a protective role since it promotes the reduction of atherosclerotic plaques.

  Causes and risk factors of high cholesterol

  food

  Cholesterol is mainly produced in the liver from dietary fats. Cholesterol is not related to the amount of fat ingested, but to its quality .

  The fats in the diet are made up of fatty acids which are of three types:

  • Saturated fatty acids : In food, the  "bad" cholesterol  is found only in  animal products rich in saturated fatty acids . There is none in fruits, vegetables, vegetable oils. Fish contain very little. The main sources of cholesterol are  eggs, whole milk, offal  (liver and heart),  cold cuts and meat , especially red meat (beef and others). Cholesterol is invisible in meat. In beef, 95% of the cholesterol is in the red meat, very little in the fat;
  • Monounsaturated fatty acids :  they are neutral. It is for example peanut oil, olive oil...;
  • Polyunsaturated fatty acids: they  are protective and are found in certain vegetable fats (corn, soybean, sunflower, rapeseed, walnut oils) and fish oils. They are not involved in the synthesis of cholesterol. They increase the rate of HDL useful for the elimination of cholesterol.

  • An unsuitable diet (rich in animal fats) can lead to hypercholesterolemia and therefore to artherosclerosis.

    However, nature is unfair and there is an individual (often familial) sensitivity to animal fats. Some individuals will be able to eat high amounts and maintain low cholesterol levels . Others will have high cholesterol with a low fat diet of the same type.

    After the age of 80, the relationship between cholesterol and mortality is rather reversed: low cholesterol levels increase the risk of cancer, depression and non-cardiovascular death.

    Iatrogenic or drug-induced hypercholesterolemia

    A number of drugs are likely to increase blood cholesterol :

    • Oral contraceptive ;
    • Certain hormone replacement  therapy for menopause (HRT);
    • Certain beta- blockers ;
    • Certain thiazide diuretics ;
    • Retinoids used in the treatment of acne ;
    • Corticosteroids . _

    Birth control pill and hyperlipidemia

    In the absence of an associated risk factor (including tobacco) and with a diet low in saturated fats, the pill can be prescribed up to a total cholesterol level equal to 3 g/l .  A very low dose pill is however recommended .

    The pill remains contraindicated in the event of hypertriglyceridemia > 2 g/l.

    Hypertriglyceridaemia

    Triglycerides (TG) are mainly carried by VLDL and largely depend on the metabolism of sugars ; they are deleterious because providers of atheroma.

    Normal triglyceride levels are:

    • In humans: 0.5 to 1.5 g/L or 0.6 to 1.7 mmol/L ;
    • In women: 0.4 to 1.6 g/L or 0.45 to 1.5 mmol/L .

    Isolated hypertriglyceridemia (HTG) is not an independent coronary risk factor . An HTG must always evoke or seek :

    • Obesity ; _
    • Alcohol consumption , sometimes even moderate;
    • A carbohydrate metabolism disorder : diabetes and/or insulin disorder;
    • Kidney failure ;
    • Hypothyroidism ; _ 
    • A drug origin (oral contraceptive, vitamin A derivatives, thiazide diuretics, beta-blockers, corticosteroid therapy);
    • More rarely: stress, viral hepatitis, AIDS, pancreatitis ...

    Protective factors

    A number of biological factors are "protective" factors:

    • HDL-cholesterol > 1.6 mmol/l i.e. 0.60 g/l (confirmed on several measurements), allows a risk factor to be subtracted;
    • Pre-menopausal women - or post-menopausal women on TSH ( Hormone Replacement Therapy ).

    • Symptoms of high cholesterol

      Strictly speaking,  there is no clinical sign that can certainly evoke hypercholesterolemia .

      The search for this metabolic disorder must be made:

      • Either during a systematic health check ;
      • Or when faced with a patient who already has a cardiovascular risk factor ( arterial hypertension , obesity, smoking, man over 45, postmenopausal woman, oral contraceptive, cardiovascular family history, stress, etc.);
      • Either in a subject already carrying a disease linked to atherosclerosis (arteritis of the lower limbs, angina pectoris, myocardial infarction , cerebrovascular accident, renal failure, etc.).

      Cholesterol measurement

      The simple determination of total cholesterol (TC) is not sufficient. It is also necessary to measure HDL-Cholesterol and triglycerides (TG).

      From these three figures, it is possible to calculate the level of "bad cholesterol" or LDL-Cholesterol:

      • In grams/litre: LDL Chol = total Chol - HDL Chol - (TG x 0.16);
      • In mMoles/Litre: LDL Chol = total Chol - HDL Chol - (TG x 0.37).

      The evolution of hypercholesterolemia

      The major complication of excess cholesterol is the formation of atherosclerosis . The symptoms that the carrier patient will present will totally depend on the affected arteries :

      • Coronary arteries : angina pectoris (angina) and myocardial infarction;
      • Cerebral arteries : cerebrovascular accidents (CVA) by thrombosis of one or more arteries supplying the brain;
      • Aorta : aortic aneurysm, aortic dissection ;
      • Lower limbs : obliterating arteritis of the lower limbs (PAD);
      • Renal arteries : renal arterial hypertension by nephroangiosclerosis (obstruction of the renal arteries and arterioles).

      Cholesterol: diagnoses to eliminate

      The isolated discovery of total hypercholesterolemia is not sufficient to affirm the chronic existence of this metabolic disorder. Some hypercholesterolemias are secondary :

      • When taking medication : cortisone, pill, retinoids, antihypertensives, etc.; 
      • The existence of a disease : hypothyroidism .

      It will then suffice to interrupt the taking of the drug responsible or to treat the hypothyroidism for the lipid metabolism disorder to disappear.

      Other hypercholesterolemias are genetic and hereditary , and particularly difficult to treat.

      You should also know that a meal very high in fat can temporarily increase cholesterol levels . The return to a normal diet is then enough to normalize blood cholesterol.

    • Cholesterol treatment

      When you want to reduce the amounts of cholesterol present in the body, what are the possibilities? The easiest and most sensible solution is to reduce cholesterol intake through diet. This is the first thing a doctor will suggest if your blood lipids are low. When this solution is insufficient, the doctor may resort to medication.

      Diet

      Today the average food provides about 600 mg of cholesterol per day while it should not exceed 300 mg.

      The patient must:

      • Preferably consume polyunsaturated and monounsaturated vegetable fats (sunflower, corn, soy, rapeseed, nuts, olives, grape seeds);
      • Avoid fats of animal origin and saturated fats (whole milk, butter, fatty meats, deli meats, etc.);
      • Avoid foods high in cholesterol : egg yolks, offal (brains, kidneys, liver), fresh cream, lobster, shellfish, fish eggs including caviar;
      • Prefer fish, veal, poultry, horse to fatty meats;
      • Consume  very little alcohol .

      When the diet is not enough to bring blood cholesterol levels back to normal, lipid- lowering or cholesterol-lowering drugs should be prescribed.

    • Physical activity

      To fight against "bad" cholesterol and increase the level of "good" cholesterol, physical exercise is essential in addition to a balanced diet . Rest assured, 30 minutes of walking a day is enough to be effective. Moreover, it is the regularity of the physical activity which counts and not the performances. Choose gentle sports such as swimming or brisk walking, which are suitable even for beginners. 

      Medications: lipid-lowering drugs

      There are several major families , including fibrates and statins .

      The strategy of current drug treatments for hypercholesterolemia has two main axes :

      • Decrease the natural production of cholesterol by the liver:

      This can be achieved by inhibiting certain enzymes in the manufacturing chain such as HMG CoA reductase, translate HydroxyMethylGlutaryl CoenzymeA reductase. An enzyme is a protein that will cause or facilitate a biochemical reaction. HMG CoA reductase is a key enzyme in the synthesis of cholesterol in the liver. Its inhibition therefore reduces blood cholesterol levels because 70% of the cholesterol in our body comes from our liver. It is one of the modes of action of lipid-lowering agents of the statin family ( simvastatin , pravastatin , fluvastatin , cerivastatin and atorvastatin ).). This family is likely to interact with other drugs such as oral anticoagulants; 

      • Increase the natural removal of cholesterol from the bloodstream  : 

      The lipid-lowering agents of the fibrate family ( clofibrate , fenofibrate , ciprofibrate , bezafibrate and gemfibrozil ) allow, among other things, a modification of the uptake of cholesterol , and in particular triglycerides circulating in our blood. In addition, part of the blood cholesterol is naturally excreted in the intestine by the bile, in the form of bile acids. In the intestine, these bile acids are reabsorbed more or less depending on certain factors. By preventing this reabsorption, elimination in the stool is increased and the amount of cholesterol in the blood is reduced. Colestyramine _is a resin that blocks bile acids in the intestine and prevents their reabsorption. This leads to a drop in cholesterol in the blood. This medication can cause constipation, which can sometimes lead to discontinuation of treatment. In addition, it also decreases the absorption of other drugs, resulting in drug interactions.

      When only the triglyceride level is high (normal cholesterol), if the diet and the elimination of alcoholic beverages are not enough, we use fibrates or fish oils rich in so-called omega 3-polyunsaturated fatty acids.