Although it is made in the body, L-Arginine is also available from food and as a supplement that is particularly popular with men. It has a reputation for improving sexual function by boosting blood flow to the genitals, possibly preventing erectile dysfunction as well as improving athletic performance, although this is not an official health claim that is made for the product.
Dr Sarah Brewer says: ‘L-Arginine is an amino acid that helps to dilate arteries and maintain a healthy blood flow throughout the body, including the genitals, so it has been proposed that it may improve sexual performance in both men and women. It is also used to help reduce blood pressure. Research suggests that L-Arginine also promotes wound healing.’
What does L-Arginine do?
L-Arginine is an amino acid vital to help the body make protein which is essential for the growth of cells and tissue repair.
It is converted in the body into a chemical called nitric oxide. Nitric oxide helps to improve blood circulation throughout the body, causing blood vessels to relax and open wider for improved blood flow. L-Arginine is also involved in the release of a hormone called insulin which is used to control blood sugar levels, as well as growth hormones.
High blood pressure (hypertension)
More than one in four people in the UK have high blood pressure, but many are unaware that they have the condition. Worryingly, if it’s left untreated it may increase your risk of serious problems, such as heart attack and stroke.
There’s evidence that L-Arginine can reduce blood pressure. An analysis, by Soochow University, China, of 11 trials involving 387 participants using L-Arginine supplements, found that their blood pressure was significantly lowered.
Another study in 2015, by the Shiraz University of Medical Sciences, found participants who took an L-Arginine supplement for eight weeks had a significant decrease in blood pressure and an increase in HDL ‘good’ cholesterol compared to those who took a placebo.
L-Arginine is thought to improve blood flow to the genitals in men and women due to its role in producing nitric oxide, which dilates blood vessels and improves circulation, potentially improving erections in men and clitoral sensation in women.
Erectile dysfunction is an extremely common condition – particularly among older men – and it’s estimated that half of all men between the ages of 40 and 70 will have it to some degree. One Japanese study, found that a combination of L-Arginine and Pycnogenol® significantly improved erectile function, and sperm quality in infertile men.
Similarly, L-Arginine may also help women who have a low libido. One study by the University of Texas, found women who took L-Arginine combined with yohimbine (a chemical derived from the bark of the African yohimbe tree), had a substantially increased vaginal pulse after they watched an erotic film when compared to those who took a placebo.
Getting L-Arginine from your diet
L-Arginine-rich foods include red meat, poultry, fish and dairy products, as well as nuts, tofu, lentils, wheat flour, eggs and chickpeas. Alternatively, take an L-Arginine supplement.
L-Arginine is considered safe to use in the short term for most people. Side effects can include abdominal pain, bloating, diarrhoea, gout, blood abnormalities, allergies, respiratory inflammation, worsening of asthma and low blood pressure.
If you are pregnant or breastfeeding avoid taking it as there hasn’t been enough research to determine its safety. Consult your doctor before taking L-Arginine if you are being prescribed medication for high blood pressure and/or erectile dysfunction, or if you have low blood pressure.
There is currently no UK or EU recommended daily allowance; a standard dose is one to two 750mg tablets a day.