What is L-arginine?
L-arginine is an α-amino acid. Amino acids (AS) are chemical compounds that, in addition to an amino group, also have a carboxylic acid group. They are the smallest building blocks of albumen (proteins) and therefore play a crucial role in building the tissues in the body. For this purpose, the individual proteinogenic α-amino acids are linked to form chains in the body cells as part of protein biosynthesis.
The substance was first discovered in 1886 by the German chemist Ernst Schulze and his doctoral student. With four nitrogen groups, arginine is the amino acid with the highest nitrogen content. This is why the amino acid plays a crucial role in the production of nitrogen oxide (NO). NO is found as a regulative substance not only in the blood vessels and in the brain, but also assumes a control function in the production of white blood cells (leucocytes).
L-arginine is an amino acid that is widely used. It is, for example, in peas, meat and cow's milk. However, these foods do not contain arginine as a protein component, but rather in the bound form. In the human organism, the amino acid in the urea cycle, also known as the ornithine or Krebs-Henseleit cycle, is formed from the amino acids aspartate and ornithine and the carbamoyl phosphate.
Arginine - Function and effects
L-arginine is probably one of the most versatile amino acids in the human body. So the substance is not only part of the urea cycle, but also involved in the formation of nitrogen oxide. Arginine can also be converted into various other bioactive substances such as creatine or agmatine.
Arginine in urea metabolism
In the human protein metabolism, ammonia is produced when nitrogenous substances are broken down. In the urea cycle, this is converted into harmless urea in the liver through several intermediate stages, such as the splitting of arginine, which can then be excreted via the kidneys. For urea cycle disorders, a pathologically increased ammonia content in the blood arises and thus causes nerve cell damages.
Arginine and nitric oxide
Not only the formation of urea, but also the production of nitrogen monoxide (NO) is of central importance for well-being and health. Nitrogen monoxide, which is made up of an oxygen and a nitrogen atom, is produced in the innermost layer of the blood vessels (endothelium) and other tissues in the body in a multi-stage reaction and are released when necessary.
The starting substance for this reaction is the amino acid L-arginine. The production of NO is therefore not possible without arginine. Nitric oxide controls various important metabolic processes in the body. In this way, NO not only promotes vasodilation and thereby improves blood flow, but also reduces deposits in the vessel walls. NO can also reduce free radicals and maintain the elasticity of blood vessels by inhibiting the growth of smooth muscle cells.
Arginine, creatine and agmatine
The body can also produce creatine from the amino acids arginine, glycine and methionine in the kidneys, liver and pancreas. This non-proteinogenic amino acid primarily contributes to the energy supply to the muscles. Creatine can also improve oxygen uptake in the brain, reducing mental fatigue.
Agmatine is another metabolite of the amino acid arginine. The guanidine compound not only takes on a function as messenger (neurotransmitter), but also has neuroprotective effects. So it can help protect nerve cells. The substance also plays a role in the functionality of the immune system.
The versatile arginine takes on various tasks in the body:
- it has a positive effect on the blood circulation
- it has a hypotensive effect
- it has a metabolic and circulatory effect
- it stimulates insulin production
- it improves the insulin sensitivity of the cells
Furthermore, the amino acid affects the hormonal balance and the immune system.
Basically, a distinction can be made between L-arginine and L-arginine hydrochloride (HCL) in arginine supplements. Both arginine base and arginine HCL are available in raw material form. These two forms differ significantly in terms of purity and also in terms of the pH level.
The L-arginine base corresponds to the actual amino acid L-arginine. The purity is between 98 and 100 percent. This means that the dietary supplement consists of almost 100 percent arginine. Although arginine is an amino acid, chemically it is one of the bases. The pH of the arginine base is between 10.5 and 12 according to international standards and is therefore beneficial for the organism.
Arginine hydrochloride (HCL) consists of a base and a hydrochloric acid. Unlike the arginine base, the purity here is only about 75 percent. The substance is easier to dissolve in water and has a neutral taste. The pH is between 6 and 6.5 and is therefore in the acidic range.
The food supplements can also be differentiated based on the manufacturing process. Fermentation is used to produce the arginine base. Bacteria and enzymes convert basic plant materials such as barley. Arginine hydrochloride, on the other hand, is usually obtained by extraction. The main raw materials are feathers that come from ducks from factory farming. In many cases, however, it can't be ruled out that these starting substances - and thus also the arginine hydrochloride - contain pharmaceutical residues or heavy metals.
The degree of purity and the basic pH are clear advantages of the arginine base. Since the substance is of plant based origin, the arginine base is also suitable for vegetarians and vegans. The distinction between arginine base and arginine hydrochloride is particularly important when it comes to the dosage. A capsule with 700 mg arginine base also contains almost 700 mg arginine, whereas a food supplement with 700 mg arginine hydrochloride only contains around 525 mg of the amino acid.
The natural protein building block arginine is responsible for numerous processes in the human body. Although the substance is contained in various foods and the body itself produces arginine, it can still lead to a deficiency.
In adults, the organism only produces very small amounts of the amino acid, although the need increases with age. Especially people with vascular diseases such as arteriosclerosis and patients with high blood pressure or dementia need more arginine. The need is also increased during pregnancy and with psychological and physical stress. If the daily requirement cannot be covered by foods such as sunflower seeds or legumes, an arginine deficiency can occur.
Symptoms of an arginine deficiency
A low level of arginine combined with a high level of ADMA in the blood is particularly critical. ADMA, the asymmetric di-methyl arginine, acts as a counterpart to arginine in the body. It inhibits the conversion of the amino acid into nitric oxide and can lead to a lack of NO. A sufficient supply of arginine can counteract this.
An arginine deficiency can lead to the following complaints:
- High blood pressure
- Diabetes mellitus (Diabetes)
- Performance disorders in the brain up to dementia
- Mood swings
- Susceptibility to infections
- Wound healing disorders
- Restlessness and insomnia
There is no clear dosage recommendation for taking L-arginine. The dosage depends on your age as well as on your own life situation, diet, body weight, and health status. The minimum recommended amount is between 3000 and 6000 mg per day. The effect of the amino acid begins about 20 minutes after ingestion and lasts for about three hours. In order to achieve a long lasting effect, arginine should be taken throughout the day.
There are various metabolic disorders that are associated with disorders in the arginine balance. In addition to the ornithine transcarbamylase deficiency, or OTC deficiency for short, this also includes arginine succinic acid disease and argininemia. These diseases are all congenital, so that the first symptoms often appear as early as childhood.
Arginine and metabolic disorders in children
The OTC deficiency is inherited sex-related on the X chromosome, so that both boys and girls can get sick. However, boys are more often affected by the disease. Due to the lack of enzymes, the urea cycle is disturbed. There are increased levels of ammonia in the blood and lower concentrations of citrulline and arginine in the blood. In addition to ammonia-binding drugs, those affected must also substitute amino acids.
Arginine succinic acid has a defect in the enzyme argininosuccinate lyase. This enzyme is responsible for splitting the argininosuccinate into arginine and fumarate in healthy people. A deficit leads to disturbances in the course of the urea cycle with symptoms such as vomiting or lethargy. While the early form already occurs during infancy, symptoms such as high blood pressure or liver diseases only manifest in the late form in older age. Arginine supplementation is also required for arginine succinic acid disease.
In contrast, argininemia, which is caused by a deficiency in the enzyme arginase, shows increased arginine levels in addition to increased ammonia levels in the blood. Neurological damage and delayed mental development can occur.
Arginine and arteriosclerosis
In 1998, the American pharmacologist Louis José Ignarro, along with Robert F. Furchgott and Ferid Murad, received the Nobel Prize in Medicine for his research on the substance nitrogen monoxide (NO). The amino acidarginine played a crucial role in the findings. The Nobel Prize winner emphasised that arginine can counter vascular damages.
Arteriosclerosis - Causes and origin
Arteriosclerosis, also known as vascular calcification, is a chronic inflammatory reaction in the vascular walls, which is associated with the storage of fats and cholesterol esters - and thus with a narrowing of the vessels. The disease shows up in the coronary arteries as well as in the leg arteries and the carotid artery. Cardiovascular diseases caused by arteriosclerosis are among the most common causes of death in Germany.
There are various explanatory models for the development of arteriosclerosis. One of these models is the nitrogen hypothesis.
Nitric oxide, arginine and arteriosclerosis
According to recent research, the substance nitric oxide is involved in the development and progression of the disease. The vascular endothelium, e.g. the inner layer of the blood vessels, has cells that can produce NO. For example, NO ensures that the vessels widen and counteracts the build-up of plaque in the vessel walls. However, if these cells do not produce enough nitrogen monoxide, there is a so-called endothelial dysfunction. This in turn benefits the development of arteriosclerosis and thus increases the risk of a heart attack or stroke.
A lack of NO in the blood vessels can have various causes. One of these causes is a (relative) arginine deficiency. Obesity, smoking, or diabetes mellitus can further promote arteriosclerosis. Professor John Cooke from Houston, also known as a pioneer in arginine research, even described arteriosclerosis as a kind of 'arginine deficiency disease'. In his animal models, Cooke was able to show that the administration of L-arginineled to an improved endothelium-dependent relaxation of the vessels and at the same time to a reduced formation of the dangerous arteriosclerotic plaques.
Drexler et al. successfully transferred these positive results from animal studies in 1991 to patients with cardiovascular diseases. Here, too, the (intravenous) administration of L-arginine improved vascular mobility andrelaxation. The effects of arginine on the vascular status were also positive in additional studies, especially for patients with high cholesterol and coronary artery diseases (CHD).
Arginine and high blood pressure
High blood pressure (hypertension) is a common illness that often develops gradually and can have serious consequences. According to the guidelines of the German Hypertension League DHL - German Society for Hypertension and Prevention, hypertension occurs when the blood pressure exceeds systolic values of 140-159 mmHg and / or diastolic blood pressure values of 90-99 mmHg several times. Up to 45 percent of the European population suffers from high blood pressure and an increase with age can be observed.
High blood pressure risks
With hypertension, the pressure in the blood vessels is increased. If the high blood pressure remains untreated for a long period of time, this overloads vital organs such as the heart. As a result, the risk of a heart attack or a stroke as well as kidney failure or visual impairment is significantly increased. Symptoms such as dizziness, headaches, or palpitations can indicate increased blood pressure but hypertension often goes unnoticed for a long time.
Lower high blood pressure with L-arginine
L-arginine can counteract the increase in blood pressure in various ways. The amino acid is an important component of nitrogen monoxide, which is (also) responsible for the dilation of the blood vessels. A lack of arginine and NO leads to a reduced elasticity of the blood vessels, increases the risk of developing arteriosclerosis and thus also promotes high blood pressure.
Arginine also modulates the so-called renin-angiotensin-aldosterone system (RAAS or RAS for short). The RAAS regulates the body's electrolyte and fluid balance and thus has a decisive influence on blood pressure. In a study by Higashi et al., arginine showed an inhibitory effect on the angiotensin converting enzyme (ACE). This promotes the conversion of the substance angiotensin I into the form angiotensin II. Angiotensin II in turn stimulates the release of the antidiuretic hormones (ADH) and the hormone aldosterone and thus causes an increase in blood pressure. By inhibiting the angiotensin converting enzyme, arginine can counteract the increase in blood pressure. The same mechanism is used by ACE inhibitors, which are used to lower blood pressure by medication.
Arginine for circulatory disorders
The body's cells need oxygen all the time to survive and perform their tasks. The oxygen-rich blood reaches the organism from the lungs through the heart. Constricted or clogged arteries can stop the blood flow and therefore also obstruct the oxygen transportation. The result is an arterial circulatory disorder, which is initially accompanied by cold hands or feet as well as dizziness and in later stages with ulceration or angina pectoris. Peripheral arterial diseases (PAD) are also a possible consequence of circulatory disorders. The main cause of these circulatory disorders is arteriosclerosis.
Arginine and peripheral arterial diseases (PAD)
The chronic arterial occlusive disease of the extremities is characterised by the progressive occlusion of the arm and / or leg arteries. The main symptom is pain when walking. Patients have to stop walking so that it looks like they are lingering in front of every shop window and looking in. The disease is therefore also known as a window shopper's disease.
Various studies suggest that L-arginine can relieve the uncomfortable symptoms of window shopper's disease. Ina 1998 study by Böger et al., patients with pAD took eight grams of L-arginine twice a day over a period of three weeks. During this time, the symptoms significantly improved. If pain occurred quickly while walking, the patient was able to walk more than twice as long after taking it. There was also a widening of the femoral artery (arteria femoralis) mediated by the vascular endothelium. Other studies also found a link between L-arginine and chronicarterial diseases.
Circulatory disorders and oxidative stress
Circulatory disorders can affect the arteries of the arms and legs as well as the blood vessels in the brain or the coronary arteries. The undersupply of oxygen has extremely drastic consequences. Stroke and heart attack are among the leading causes of death in Germany. The influence of oxidative stress on the development of the disease has been demonstrated for a large number of cardiovascular diseases.
With oxidative stress, free radicals are generated in the body with various metabolic processes. These reactive oxygen compounds can damage or even completely destroy molecules, cells and tissues. The short-lived and extremely reactive molecular fragments are increasingly formed when the combustion processes in the mitochondria e.g. in the 'power plants' of the cells, are overloaded. Exogenous factors can also benefit the development. This includes among others:
- Exposure to heat
- Cigarette smoke
- Environmental toxins
- UV and ionising radiation
The species of superoxides, also known as oxygen radicals, plays a central role in the development of vascular diseases. The superoxides capture the nitrogen monoxide from the vessel walls and convert it into highly oxidative peroxynitrite. Nitric oxide is an important vessel widening substance, a so-called vasodilator. A deficiency promotes the development of arteriosclerosis, high blood pressure and other circulatory disorders. Arginine can intervene in this imbalance and therefore act as an important protection against oxidative stress.
Arginine and potency
If in more than two thirds of all cases a man does not get an erection or cannot keep his erection for a period of six months, then this is a potency disorder. Sexual intercourse is no longer possible. Depending on the age, every tenth to every third man is affected by the ED. The erectile dysfunction can have a negative impact on self-confidence and can also strain the partnership.
Causes of an erectile dysfunction
While this is mainly due to psychological triggers in younger men, older men have primarily physical causes behind erectile dysfunction. In many cases, the erectile dysfunction is based on calcification of the small arteries that supply the male member with blood. In order to become stiff, the erectile tissue of the penis must fill with blood. If the blood supply is insufficient, the penis remains limp. Nerve damage and diseases such as dementia, Parkinson's or multiple sclerosis can also lead to erectile dysfunction in rare cases. Relationship problems, alcohol, drugs, and depression can also affect potency.
Arginine and erectile dysfunction
The erectile dysfunction can be regarded as an early warning sign. If there is a circulatory disorder, it is by no means a local problem. Other vessels in the body are also affected, so there is an increased risk of a heart attack or stroke. Arginine as a precursor of nitrogen monoxide can help relax the vessel walls and improve blood circulation. This not only has a positive effect on erectile function, but also contributes to a good oxygen and nutrient supply for the entire body.
NO as well as L-arginine are not only important for the condition of the penile arteries. In order for the swollen penis bodies to fill with blood, the smooth muscles must relax. As a result, the blood vessels of the penis expand so that more blood can flow in. At the same time, the muscle cells squeeze the veins so that more blood remains in the penis. The relaxation of the erectile tissue muscles is a process mediated by the parasympathetic nervous system and requires nitric oxide.
Arginine, pine bark extract and erectile dysfunctions
In a study from 2010, the combination of L-arginine and pine bark extract in particular has proven to be an effective treatment method for erectile dysfunction. Pine bark extract is made from the bark of the maritime pine and, in addition to polyphenols and catechins, also has a high proportion of oligomeric procyanidins (OPC).
In Stanislavov's et al. study, 40 men between the ages of 25 and 45 who had erectile dysfunction received 1.7 g of L-arginine per day for one month. After this period, only two men reported an improvement in their symptoms. This dose was maintained in the second and third months but was supplemented by 40 and 120 mg of pine bark extract. After these three months, 92.5 percent of the study participants had a normal erection ability.
Users also reported about an improvement in potency through the combination of the amino acid arginine and maca. The bulb of the maca plant has been used as a food and medicinal plant for around 2000 years. Maca is now also known in Europe as a so-called superfood and natural aphrodisiac. So far, few studies have looked at the effects of maca on erectile dysfunction. However, there is a positive effect in the few available research work, so that taking it together with arginine may make sense.
Diabetes and arginine
Worldwide, several million people suffer from the metabolic disease diabetes mellitus, which is popularly known as diabetes. A basic distinction can be made between type 1 and type 2 diabetes. While there is an absolute insulin deficiency in type 1 diabetes, type 2 diabetes is based primarily on insulin resistance. This means that there is actually enough insulin but the body cells no longer respond adequately to the hormone.
As a result, there is a chronic increase in blood sugar levels and a significantly increased risk of complications such as diabetic foot syndrome, diabetic nephropathy or diabetic angiopathy. The vessels in particular suffer from the high blood sugar levels. If the sugar derailment persists for a longer period of time, the arterial calcification increases and hypertension and circulatory disorders occur. This also increases the likelihood of cardiovascular diseases, heart attacks, strokes, as well as damages to the nerves and kidneys.
Prevent vascular damage with L-arginine
Arginine is the only amino acid that acts as a precursor to the messenger nitrogen monoxide (NO). NO plays a crucial role in vascular health. So the substance not only contributes to relaxation and thus to the dilation of the blood vessels, it is also involved in the regulation of blood pressure. The availability of the amino acid arginine is therefore an important prerequisite for vascular health and can improve the state of health, particularly in the case of metabolic disorders such as diabetes mellitus.
L-arginine and insulin sensitivity
L-arginine as a precursor to nitrogen monoxide can also have a direct influence on the insulin sensitivity of the body's cells. For people with type 2 diabetes mellitus, the body cells react less to the hormone insulin than the cells of healthy people. This is particularly evident in the liver cells, muscle cells, and adipose tissue. This phenomenon affects not only the effects of the body's own insulin, but also that of the insulin supplied from outside.
By activating nitrogen monoxide, arginine can improve the insulin sensitivity of the body's cells. These react more quickly to the insulin, causing the blood sugar level to drop. Under certain circumstances, diabetics with insulin resistance with regular supplementation of L-arginine can reduce their insulin dose or even completely go without externally supplied insulin.
Arginine, sugar metabolism and insulin production
Arginine has an influence not only on insulin sensitivity, but also on the production of insulin and the overall sugar metabolism. In this way, arginine can stimulate the cells of the pancreas to produce and release the important hormone. The antioxidant properties of the amino acid also have a positive effect on blood sugar levels. This shows both a short-term drop in blood sugar levels and a positive influence on the so-called HbA1c value. This laboratory value allows an assessment of the blood sugar values of the past eight to twelve weeks.
Tinnitus and arginine
People with tinnitus permanently or temporarily hear buzzing, whistling, humming or similar noises that do not exist objectively. The tinnitus can occur in one ear or in both ears. Possible causes of ear noises include:
- Bang or sound trauma
- Sudden hearing loss
- Meniere's disease
- Tumors of the auditory nerves
- Substances that damage the ear
Stress can increase the intensity and frequency of ringing in the ears. It is not uncommon for tinnitus to be accompanied by symptoms such as sleep disorders, depression, or even anxiety.
Improve blood flow to the ear
In many cases, no direct cause for the ear noises can be found. Doctors also speak of idiopathic tinnitus. In a 2006 study, Neri et al. was able to show a connection between oxidative stress and idiopathic tinnitus. They found low concentrations of nitric oxide (NO) in the blood of the jugular vein in tinnitus patients and suspected that this led to a dysfunction of the vessels and thus to poor circulation in the small vessels of the ear.
However, NO not only serves vascular health, it also plays a role in the functioning of the nerves. Among other things, the substance is responsible for the development and regeneration processes of the neurons. The researchers Pall and Bedient even consider disorders in NO synthesis as one of the causal mechanisms in the development of tinnitus. Arginine, as a precursor to nitrogen monoxide, is therefore an important component of tinnitus therapy.
L-arginine and the immune system
Our body is constantly attacked by viruses, bacteria and other microorganisms. Some of these pathogens can cause life-threatening infections. The immune system protects the body from foreign structures and therefore from diseases. The body's defence is a complex system that is influenced by numerous factors. One of these factors is the amino acid arginine.
Arginine and T lymphocytes
The amino acid has a significant impact on T lymphocytes. These white blood cells are an important part of the acquired immune system, because they circulate in the blood and look for foreign antigens. If the T cells have identified a pathogen using so-called antigen-presenting cells, they are activated if there is a simultaneous co-stimulance. The T cells grow and differentiate into T helper cells, regulatory T cells, or T killer cells.
The T helper cells produce cytokines that attract other cells of the immune system to fight the pathogen. T-killer cells can destroy the diseased or infected cell directly. In contrast, the regulatory T cells are primarily intended to protect intact body cells from an excessive immune response.
Arginine acts as an important modulator of T cell functions in the immune system. The proliferation, e.g. the multiplication and the differentiation of the T cells, depend on the amino acid. If there is a lack of arginine, the T helper cells also produce fewer cytokines. Without these important soluble messenger substances, an adequate immune response is not possible. Arginine deficiency also affects the CD3 complex. This is involved in the transmission of the signal to activate the cell. A down regulation of the CD3 complex plays a crucial role in the development of cancer and chronic infections. Arginine also stimulates the formation of lymphocytes in healthy people. Thus, the amino acid could also be suitable for general strengthening of the immune system and for the prevention of diseases.
Arginine and the neonatal immune system
The development of the human immune system begins in the first weeks of pregnancy. The immune system is partly innate, but is still unripe at birth. Premature babies, in particular, are therefore prone to infections with serious illnesses. In newborns and premature babies, arginine appears to be of particular importance for intestinal mucosal immunity. A lack of arginine in newborns increases the susceptibility to colonisation of intestinal pathogens. These not only damage the intestine locally, but can weaken the entire child's immune system.
Supplementing L-arginine immediately after birth can support the development of the immune system and thus protect against infections. In one study, Briana et al. administered arginine to newborns with a very low birth weight. This significantly reduced the risk of the advanced stages of the feared necrotising enterocolitis. A meta-analysis by Garg et al. also found a connection between the supplementation of L-arginine in newborns and a lower mortality rate due to the dangerous bowel disease.
Arginine in sports
The 2010 Bailey et al. study, however, comes to another conclusion with regard to endurance sports. The researchers gave nine healthy men between the ages of 19 and 38 a drink containing six grams of arginine or a placebo drink without active ingredient. The arginine group found a higher level of nitric oxide in the blood after training. This also indicates improved blood circulation. There was also an improvement in VO2max. The VO2max represents the maximum amount of oxygen that a person can absorb and utilise under stress. The better the VO2max, the better endurance sports performance can usually be achieved.
Arginine against stress
Whether at home or at work - more and more people are suffering from stress. Stress and burnout have long ceased to be managerial diseases, but affect people of all ages and occupations. School children and mothers also increasingly show stress-related symptoms such as irritability, stomach and intestinal problems, sleep disorders, or back pain.
The stress hormone cortisol
Cortisol is one of the most important stress hormones. It belongs to the group of glucocorticoids and is increasingly produced and distributed in stressful situations. From the body's point of view, this makes a lot of sense, because the hormone increases the blood sugar level and thus provides energy for the cells. It also increases blood pressure and has an anti-inflammatory and immunosuppressive effect. All of these properties are useful for acute stress. It only becomes problematic if the cortisol levels are permanently increased due to constant stress. A chronically elevated cortisol level is associated with high blood pressure, cardiovascular diseases and obesity.
Arginine lowers cortisol
In order to prevent secondary diseases, the cortisol level should be reduced in case of permanent stress. The amino acid arginine can be helpful here. Especially in combination with the essential amino acid lysine, arginine can significantly reduce the cortisol concentration in the blood. In a Japanese study, however, the normalising effect on cortisol levels after a stress-causing event was only found in men. The combination of lysine and arginine had no effect in women.
Arginine against the effects of stress
Chronic stress leads to permanent activation of the sympathetic nervous system. This is part of the autonomic nervous system and is usually in a balanced relationship to the calming parasympathetic nervous system. With stress and burnout, however, the sympathetic nervous system gains the upper hand. It increases the heart rate, constricts the blood vessels in the skin and inhibits the insulin production and digestive functions. Excessive sympathetic activity over a longer period of time favors the development of cardiovascular diseases and vascular damage.
As a precursor to vaso-dilating and hypotensive nitrogen monoxide, the amino acid L-arginine can counteract the symptoms of stress and improve the blood circulation.
L-arginine and cancer
In addition to cardiovascular diseases, cancer is the leading cause of death in Germany. While digestive and lung and bronchial cancer are most commonly diagnosed in men, breast cancer is the most common diagnosis in women. The number of new cases is steadily increasing. The WHO estimates that in 2030 more than 21 million people worldwide will develop cancer each year.
Cancer and nutrition
In their research, Max Parkin and his research team from the Center for Cancer Prevention at Queen Mary University in London concluded that around 40 percent of all cancers can be avoided. A lack of nutrients due to an unhealthy diet is responsible for around nine percent of all cancer cases. Especially intestinal cancer correlates to a high degree with an unhealthy and unbalanced diet. A sufficient supply of all (semi-) essential amino acids is undoubtedly part of a preventive diet. Scientifically, however, it is controversial as to whether arginine can reduce the risk of cancer.
Does arginine increase the risk of cancer?
Various studies have concluded that arginine can promote cancer growth. This is particularly the case with tumors that cannot produce arginine themselves and are therefore dependent on an external supply of the aminoacid. These include, for example, certain liver cancers, melanoma and some forms of leukemia.
They need arginine for their growth, but are unable to convert citrulline to arginine. Some studies report success in treating these cancers with the enzyme arginase. This is able to convert arginine into ornithine and thus deprive the cancer cells of their food.
Can arginine protect against cancer?
Since arginine has a positive impact on the human immune system, a preventive effect is also conceivable. The immune system not only protects against viruses and bacteria, it also fights degenerate cells in the body. If this does not work properly, the degenerate cells can multiply and spread throughout the body.
Arginine primarily supports the T cells of the immune system. They need arginine to multiply and differentiate. Differentiation in T-killer cells in particular plays a crucial role in combating cancer, since these can specifically target the tumor cells.
Arginine can also promote the production of cytokines. These body's own signaling molecules put the immune system on alert and direct various cells of the immune system to the region in which the degenerated cells are located. In cancer patients, lower arginine levels are often found in the blood serum. This may lead to partial immune system failure with regard to cancer cells.
Avoid complications with arginine
Not only the cancer itself, but also the treatment is associated with risks and complications. Some complications and side effects of cancer treatment can be prevented with dietary supplements. Patients who receive supplements with L-arginine and other nutrients such as glutamine or omega fatty acids are at lower risk of getting an infection after surgery. Likewise, the wounds of patients receiving supplements often heal faster and they spend less time in the hospital.
L-arginine against cachexia
L-arginine also has a positive impact with regard to the dreaded cachexia. This common consequence of cancer is characterised by the loss of fat and muscle mass as well as severe underweight. Around 20 percent of all cancer deaths are a direct result of tumor cachexia. It is therefore all the more important to counteract wasting and increased weight loss at an early stage.
In a 2002 study, cancer patients who lost more than five percent of their weight received a mix of amino acids, including the amino acid arginine. This enabled the researchers to gain weight in the emaciated patients. A 2004 study of cancer and HIV patients came to a similar conclusion. The amino acid mix not only led to an increase in muscle mass, the patients also felt significantly more efficient. The subjects' blood values also improved, such as the number of red blood cells and the hematocrit and hemoglobin content were significant.
The specific connection between L-arginine and cancer has not yet been fully researched. While the growth of certain cancers can be stimulated by arginine, some studies show that the amino acid has a positive impact on the immune system and can thus help prevent cancer. The amino acid has also proven to be a valuable therapeutic component in aftercare.
L-arginine in food
The body can produce some of the amino acid L-arginine itself, but is still dependent on the external supply for an adequate supply. But which foods are particularly suitable to absorb enough arginine?
The United States Department of Agriculture has drawn up a comprehensive list of the arginine content of more than 4,000 foods. This shows that nuts and seeds in particular contain a lot of arginine.
Arginine occurrence in food in grams (per 100 g)  Nuts and seeds:
- Sesame 7.44
- Peanuts 6.24
- Pumpkin seeds 5.53
- Hemp seeds 4.55
- Chives 1,53
- Onions 1,20
- Edamame 0,72
- Lima beans 0.52
- Spinach 0,48
- Peas 0,43
- Brussels sprouts 0.22
Meat and fish:
- Pig 2.51
- Cod 3,76
- Turkey 2,3
- Lamb 2,24
- Chicken 2,17
- Octopus 2,18
Milk, milk products and egg:
- Protein 4,81
- Egg (full) 3.08
- Parmesan cheese 1.53
- Milk 1,31
- Mozzarella 1,06
- Yoghurt 0,33
The amino acid arginine can be produced in two processes. On the one hand, extraction from protein hydrolyzates from feathers of animal origin and from gelatin is possible. The protein hydrolyzate, a mixture of different amino acids, is separated by means of crystallisation or a chromatographic process for the exchange of ions. Various proteinogenic amino acids, including arginine, can then be isolated.
Arginine can also be obtained by fermentation of plant-based raw materials. Plant substances such as wheat or other types of grains are suitable for this. These are chemically converted by bacteria and enzymes in the fermentation process. Ultimately arginine is formed.
Admission and availability
However, it should be noted that not all of the amino acids contained can be absorbed by the body. On the one hand, the arginine content is reduced by cooking processes such as cooking or roasting, on the other hand, intestinal health and digestive performance generally play a role in the absorption of the amino acid. Pepper extract can improve the absorption and availability of arginine.
Arginine interacts with the following medications:
- Anti-clotting medication (anticoagulants) such as Marcumar or Dabigatran: if arginine is also taken, there is an increased risk of bleeding.
- Medication that lower blood pressure, such as ACE inhibitors or beta blockers: there is a risk of hypotension (low blood pressure).
- Medication for diabetes such as Metformin: arginine can affect blood sugar levels. The dose of the diabetes medication may need to be adjusted accordingly.
- Isoproterenol: In combination with this cardiac medication, L-arginine can lead to low blood pressure.
- Nitroglycerin: Nitroglycerin is used in the form of sprays to treat sudden heart pain (angina pectoris). If L-arginine is taken at the same time, there is a risk of a drop in blood pressure.
- Potassium-sparing diuretics: If arginine is taken with potassium-sparing diuretics, the potassium concentration in the blood can increase to hyperkalemia. This can lead to life-threatening arrhythmias.
- PDE-5 inhibitors such as Sildenafil (Viagra): If arginine is taken in combination with the active ingredient Sildenafil, there is a risk of a drop in blood pressure.
No side effects are expected when taking moderate amounts of arginine. An overdose can occur from an intake of 15 grams of arginine per day.
Anyone suffering from a herpes infection should be careful when taking arginine. Even small doses can trigger the virus and promote an outbreak of the disease. Likewise, L-arginine should not be taken after a heart attack.
Arginine side effects
Side effects rarely occur with the oral supplementation of L-arginine. With severe sensitivity and / or too high a dosage, arginine can have the following side effects:
- Stomach pain
- Sleep disorders