Choline is a widespread and indispensable biological agent. Many metabolic processes only take place with the help of choline. Choline deficiency therefore leads to a variety of health problems.
What is choline
Choline is a quaternary ammonium compound which is also a monohydric alcohol. The nitrogen atom is surrounded by three methyl groups and one hydroxyl group. Since the ammonium compound is positively charged, it is present as a salt.
It is commercially available as choline chloride. The active ingredient is found in many foods as a water-soluble semi-essential nutrient. It was first discovered in pork bile by the German chemist Adolph Strecker in 1849. In 1862 Adolph Strecker characterized and named this active ingredient. Choline used to be classified as a vitamin of the vitamin B complex, because when ingested it had a characteristic effect on the nervous system and various metabolic processes.
However, it was also recognized that it is also produced in the human metabolism from the amino acids methionine and lysine. However, the body's own production is not so high that the choline requirement can be adequately covered at any time. That is why choline is now known as a vitamin-like active ingredient. Choline is named after the Greek word for gall "Cholé". As an important component of the bile, it is responsible for the emulsification of fat-like substances and thus for the removal of fat from the liver.
Function, effect & tasks
Choline has a variety of functions in the human organism. In the body, it is converted into acetylcholine through esterification with acetic acid.
Acetylcholine is an important neurotransmitter that is responsible for transmitting nerve impulses. It plays a major role in both the sympathetic and parasympathetic nervous systems. These stimulus transmissions have a decisive influence on the intellectual performance, concentration and memory of the person. For example, at low choline concentrations, a significantly reduced concentration and memory performance were found. Choline is also involved in the synthesis of myelin. Myelin is a protein that protects the nerve tracts from external influences through insulation.
Choline is also a key component of cell membranes in the form of phospholipids. The best-known phospholipid of the membranes is lecithin. Lecithin consists of glycerine esterified with two fatty acids and choline. Cell contacts are also mediated via the membrane-bound phospholipids of the choline. In addition to folic acid and methionine, choline is also an important methyl group carrier. If there is a deficiency in folic acid and vitamin B12, choline ensures the methylation of homocysteine into methionine.
It thus helps methionine continue to function as a methyl group transferring agent. Choline also plays an important role in the bile. There, in the esterified form, it ensures the emulsification of lipids and can thus transport fat and cholesterol out of the liver. This prevents fat from building up in the liver. After all, choline is also involved in the synthesis of important hormones such as norepinephrine or melatonin.
Education, occurrence, properties & optimal values
Choline is widespread in nature. In the human organism it is made from the amino acids lysine and methionine. During biodegradation, lysine supplies the metabolite dimethylamine, which is methylated to choline by the methyl group donor methionine. In the body it is esterified as lecithin in the cell membranes, as a metabolite in the metabolism and esterified with acetic acid as the neurotransmitter acetylcholine.
Since it is bound as lecithin in the cell membranes of all living things, it can be easily taken in through food. It is found in foods that still contain cell membrane components. Egg yolks, beef liver, chicken liver, wheat germ, bacon, dried soybeans and pork contain a particularly large amount of choline. A healthy and varied diet should cover the daily choline requirement. In the case of a vegetarian diet, particular care should be taken to consume vegetables rich in choline. These include cereals and legumes.
Diseases & Disorders
Since choline plays a central role in many processes in the organism, a choline deficiency has a negative effect on the state of health. There is usually enough choline in food so that a choline deficiency should not actually occur.
Nevertheless, there are diseases that can be traced back to a choline deficiency. Excessive alcohol consumption can lead to a choline deficiency. A fat malabsorption disorder also leads to it. Furthermore, a deficiency in folic acid also leads to a secondary choline deficiency. If folic acid is missing, choline takes over the function of the methyl group carrier. It is broken down and is no longer available for other processes. The body's own synthesis is insufficient. Serious illnesses such as AIDS can also lead to a choline deficiency. The consequences of an undersupply with choline are manifold.
This is shown most drastically by the development of fatty liver. Due to the lack of choline, the fats can no longer be transported out of the liver. They are stored in the hepatocytes.As a result, the liver can no longer perform its detoxification function properly. In the long term, liver degradation occurs. In the case of deficiency, choline is no longer available in sufficient quantities for the synthesis of acetylcholine. Symptoms such as poor concentration and forgetfulness appear.
Low choline levels are often linked to high levels of homocysteine in the blood. Homocysteine is a risk factor for the development of arteriosclerosis. Furthermore, a choline deficiency also seems to worsen the pathogenesis of some diseases. Among other things, it was found that ulcerative colitis is positively influenced by the administration of lecithin. The same goes for chronic inflammation or even breast cancer.
