L-arginine is an amino acid that we take in with our food every day. Nuts, fish and soy are particularly rich in arginine-containing proteins. With the usual diet we consume about 4 to 5 grams of L-arginine per day. Healthy people can also produce sufficient quantities of L-arginine themselves or obtain it from the breakdown of body proteins.
In certain life situations such as However, the body’s own arginine production is inadequate during early childhood growth, when infections and inflammations occur or when the digestive and kidney functions are disrupted. That is why arginine is also known as a semi-essential amino acid.
L-arginine is involved in various metabolic processes in the body involved. A particularly important function is certainly that L-arginine is used to form nitric oxide (NO). However, the formation of NO can only take place if the body is sufficiently supplied with vitamin B6, folic acid and vitamin B12. NO is a gaseous radical with a signaling effect.
Through various reaction steps, it causes the vessels to widen and thus leads to a reduction in blood pressure. However, NO also protects the endothelium (inner wall of the vessel), while it inhibits the adhesion of platelets and monocytes. NO also reduces vascular oxidative stress.
Blood pressure and endothelial function
Supplementation with L-arginine can increase the availability of NO, improve endothelial function and lower blood pressure.
At doses between 4 and 24 g (mean dose 9 g), administered over an average of 4 weeks, L-arginine lowers systolic blood pressure by 2 to 5 mm Hg and diastolic pressure by around 3 mm Hg. These arginine dosages also improve endothelial function. The supplied L-arginine is particularly effective if the persons have a low plasma arginine concentration or an increased ADMA level (asymmetrical dimethylarginine). ADMA is an antagonist of L-arginine and inhibits the formation of NO.
A more recent study shows that a significantly lower daily dose of L-arginine (2.4 g) can have this effect if L-arginine is combined with B vitamins (3 mg Vit B6, 400 µ folic acid, 2 µ Vit B12) . The homocysteine level was also lowered through the administration of the B vitamins. An elevated homocysteine level is another risk factor for cardiovascular diseases.
Obesity, insulin resistance and diabetes
L-arginine may also have positive effects on body composition and insulin sensitivity. L-Arginine does not seem to reduce body weight, but it does reduce fat mass and increase muscle mass. Insulin sensitivity was also improved and inflammation parameters were reduced. So far, however, this effect has only been investigated in a few studies.
The mechanism of action is also not yet clear. The increased release of hormones (e.g. growth hormones) may play a role. The immunomodulating effect of L-arginine could also be important.
Due to its vasodilator effect, L-arginine is also known as “orthomolecular Viagra”. However, there is only little data that prove this effect of L-arginine, usually given in combination with pine bark extract. Performance-enhancing effects in combination with caffeine or creatine have not yet been shown.
The administration of arginine to pregnant women with preeclampsia or eclampsia (pregnancy high blood pressure) is also being discussed. L-arginine is also used in critically ill patients, especially trauma patients. Patients with a highly immunocompromised, inflammatory and catabolic metabolism particularly benefit from L-arginine supplementation.
L-arginine (2.5 to 5 g per day) can improve endothelial function and lower blood pressure. This effect is to be expected in people who have low arginine levels or who have high ADMA levels. The effectiveness against cardiovascular diseases, obesity, diabetes and erectile dysfunction is less well documented.
The arginine intake should be spread over the day. An accompanying supplementation with B vitamins seems sensible. It should also be noted that excessive amounts of NO can damage cells and lead to nitrosative stress. A time limit for arginine supplementation and the simultaneous administration of mixed tocopherols and vitamin C can reduce the risk of nitrosative stress.