Homocysteine: what is this amino acid and what is it for

Homocysteine: what is this amino acid and what is it for

L’homocysteine is a product of the metabolism of methionine, an essential amino acid that the body obtains from food. Know about them i reference values it is useful for avoiding health risks. L’as omocysts Bassa o altain fact, it can be an alarm bell, especially in the second case, as regards the maintenance of one’s own cardiovascular health.

What homocysteine ​​is, how it is formed and what it is used for, we see below.

What is homocysteine

Homocysteine ​​is a sulfur amino acid: in its chemical formula it contains a sulfur atom. It is a product of the metabolism, through enzymatic transformation, of the amino acid methionine, which our body absorbs directly from some foods such as milk and dairy products, eggs, meat and even legumes.

The concentration of homocysteine ​​in the blood is determined by several factors that can affect it more or less jointly: a little varied diet low in fruit and vegetables, the intake of certain drugs, some hereditary diseases, cigarette smoking, excessive consumption of coffee or other exciting drinks, folate deficiency.

Homocysteine ​​is one of the values ​​that is sought in the course of blood analysisas values high concentrations have been related to the increased risk of suffering from cardiovascular diseases, including serious ones, such as atherosclerosis, myocardial infarction, cerebral stroke and thrombosis.

Fonte: Pxhere

What is homocysteine ​​used for

As reported on the Humanitas website, a practical example to better understand what homocysteine ​​is used for is to equate it to one of the “tiles” that make up our cells. It is associated with the production of vitamins B6, B9, B12 and folates.

Together with glutamic acid and glycine it forms the glutathione. Known, the latter, mainly for its function as natural antioxidant produced by the organism itself and which plays an important role in the production and repair of tissues, in the synthesis of proteins and other molecules.

To answer the question “who produces homocysteine?“, This is converted into:

  • cysteine, in a chemical reaction in which vitamin B6 also participates
  • methionine, in a reaction in which folic acid and vitamin B12 also participate

As for the relationship between homocysteine ​​and vitamin D.it was highlighted that the increase in the former and the deficiency of the latter can be considered as potential markers of coronary heart disease.

Homocysteine ​​reference values

The international guidelines report to date similar values, but not the same, with respect to the concentration that must be considered normal. In any case, the homocysteine ​​values ​​in the plasma of a healthy adult individual should be between 5 and 12 micromoles per liter.

All values ​​that exceed this threshold are to be considered high. The desirable concentration is approx 7 micromoli per liter of plasma. However, considering how i reference values ​​of homocysteine may change according to age, sex and instrumentation in use in the individual laboratory, it is good to rely on the ranges provided by the laboratory on the report, and, of course, to hear the opinion of your doctor.

Before considering in detail the reference values ​​of the amino acid, it is important to specify how homocysteine ​​is found in the blood as a single molecule, as a dimer – that is, a form in which two molecules are joined – and also bound to some proteins. The homocysteine ​​value that is detected refers to the total amount of homocysteine ​​regardless of the form in which it is found in the circulation.

Homocysteine ​​what this amino acid is and what it is used for
Fonte: Pexels

Homocysteine ​​Reference Values ​​Table

Gender / Age Normal values High values
Lower limit Higher limit
Donne 12-19 years 3.3 μmol/L 7.2 μmol/L > 10.4 μmol/L
<60 years 4.9 μmol/L 11.6 μmol/L
Men 12-19 years 4.3 μmol/L 9.9 μmol/L > 11.4 μmol/L
<60 years 5.9 μmol/L 15.3 μmol/L

Low homocysteine

The homocysteine ​​deficiency can be due to a poor diet or, worse, to malnutrition. Some particular conditions such as pregnancy or reduced absorption can affect causing a low concentration of the amino acid. Including alcoholism and drug abuse.

Unlike what we will see with regard to high homocysteine, low levels of this amino acid detected in the plasma are not generally associated with health risks.

High homocysteine

High homocysteine ​​values ​​can have different cause and they may involve different symptoms. In general, high homocysteine ​​is much more worrying than low homocysteine ​​as important health risks are connected to it, as anticipated.


When our body is faced with deficiencies of folic acid and vitamin B12 and vitamin B6or a reduced enzyme activity of methylenetetrahydrofolate reductase (MTHFR), these anomalies may result in a accumulation of homocysteine which, in turn, is capable of causing destruction of endothelial cells, reduction of antioxidant activity, stimulation of coagulation and, ultimately, atherosclerosis and thrombosis. (Source: Humanitas)

Long-term therapy with drugs such as birth control pills, methotrexate and carbamazepine can also lead to an increase in the concentration of this amino acid in the blood.

A high value of the homocysteine ​​concentration is correlated, according to an evaluation scale, to the increase in cardiovascular risk:

  • values ​​between 16 and 30 micro-moles per liter indicate a moderate increase in risk;
  • values ​​between 31 and 100 micro-moles per liter are associated with an average increase in cardiovascular risk;
  • values ​​above 100 micro moles per liter indicate that the risk is severe.

In all subjects in which an increase in homocysteine ​​concentration is verified, the first therapeutic approach involves the correction ofPower supply and general lifestyle.

Homocysteine ​​what this amino acid is and what it is used for
Fonte: Pexels


High Homocysteine ​​Symptomsalso called hyperhomocysteinemia, a condition that may be due to a deficiency of vitamins B6 and B12 or folate, can be linked to these deficiencies and include:

  • Sense of fatigue and weakness
  • Loss of appetite
  • Diarrhea
  • Dizziness
  • Pallor
  • Tachycardia
  • Shortness of breath
  • Tingling, numbness and / or burning in the limbs


Fortunately, in most cases the homocysteine ​​concentration can be reported to normal values by administering folic acid, whether or not associated with vitamin B12. If necessary, the doctor could therefore prescribe a supplementation of these two elements.

In addition to prescribing a supplement in tablets, it is useful to increase the food intake by enriching the daily diet with foods rich in:

  • Folic acid, ie “green” vegetables such as salad, peas and spinach, dried fruit, especially peanuts and legumes, especially beans and lentils;
  • Vitamin B12, such as milk and dairy products, meat and seafood.

As for this micronutrient, those who follow a vegan diet can solve it with a food supplement. A balanced diet and an active lifestyle contribute to the maintenance of normal homocysteine ​​values.

Homocysteine ​​examination

Because homocysteine ​​is made? The dosage of homocysteinemia – whose sail è Hcy – it is generally prescribed to all people who have a high age, lifestyle and gender cardiovascular risk to evaluate, in fact, the risk of onset of coronary heart disease, thrombosis, abortion and fetal malformations.

The examination becomes routine for all those who have already suffered from heart attack, stroke and venous thrombosis. The homocysteine ​​dosage is also important in those suffering from arterial hypertension, diabetes, high cholesterol, hyperthyroidism. The homocysteine ​​test is carried out by taking blood samples in the morning and on an empty stomach and prescribed by the doctor.

The result is usually ready after one week from the day of collection. Scientific research has long defined the role of examining the concentration of this molecule in determining a person’s risk of suffering from diseases, even serious ones, of the cardiovascular system.

Source: GreenStyle by www.greenstyle.it.

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