For several years, this substance has been mentioned in the media again and again in the context of vascular calcification, heart attack and stroke. But very few people know exactly what they are about. Homocysteine is an intermediate in human protein metabolism, more specifically in the breakdown of methionine. This amino acid must be supplied daily through the diet and serves the body as an important sulfur source. Homocysteine, on the other hand, is a toxic waste product and is therefore rapidly bound, converted back into methionine with the help of vitamin B12 and folic acid, or further degraded with the help of vitamin B6 and excreted mainly via the kidneys.
Causes of increased homocysteine levels
The metabolic pathways described are important in understanding the route to a potentially dangerous surplus of homocysteine in the blood. Here are some of the causes:
- Renal function diminishes with age and homocysteine levels increase naturally (by about 10% every 10 years).
- If not enough folic acid and vitamins are added to the B group via food, homocysteine can not be reconstructed and thus eliminated. Excessive coffee consumption hinders the absorption of folic acid and B vitamins in the gastrointestinal tract.
- In the case of foods rich in methionine (eg eggs, fish, offals, Brazil nuts, maize), homocysteine is increasingly produced.
- Many drugs affect the methionine metabolism and "consume" the B vitamins or folic acid, so that they can no longer perform their duties properly. These include antibiotics, tuberculosis, antiepileptic drugs, the pill, rheumatism and expectorant.
- Certain diseases also increase the total requirement of vitamin B and folic acid, such. As diabetes, cancer, liver diseases or neuropathies.
- In renal failure, the homocysteine is no longer sufficiently degraded and excreted.
- Rarely, a congenital disorder of the amino acid metabolism is based on the metabolic pathway itself is disturbed (Homocysteinurie).
Incidentally, even a lack of exercise seems to increase the amount of homocysteine.
Too much homocysteine is dangerous
Homocysteine damages the body in different ways. So it activates platelets - and thereby promotes blood clots. It damages the cells z. B. on the inner walls of the vessels directly and - via the activation of various mechanisms - also indirectly. It encourages scavenger cells to migrate into the vessel walls and cause muscle cells to change. The consequences? Permanently elevated homocysteine levels in the blood (hyperhomocysteinemia) probably promote vascular calcification and thus the development of corresponding diseases: heart attack, stroke, arterial occlusive disease - diseases in which almost every second German citizen dies. It also seems to increase the risk of venous thrombosis. It is also discussed that homocysteine is also a risk factor for Alzheimer's disease and vascular dementia-related dementia, as well as for age-related macular degeneration (AMD), a common visual disturbance that increases with age.
Determination of homocysteine concentration in the blood is performed to determine the individual risk of atherosclerosis and associated sequelae, especially in patients who also have other risk factors, such as elevated blood lipid levels; also suspected of homocysteinuria. The blood is taken in the morning sober, 2-3 days before no methionine-rich diet should be taken and as little coffee to be drunk.
The normal value is less than 10 μmol / L (micromoles per liter). If the homocysteine level is increased, therapy with folic acid, vitamin B6 and vitamin B12 supplements is recommended - depending on the extent and other risk factors - and permanently.