Taking Nitric Oxide Supplements?

Picture from NTUC Fairprice 

A patient who does triathlons just asked if he should start taking nitric oxide supplements as his personal trainer said it can help boost his sporting performance. 

What is nitric oxide anyway? Nitric oxide is actually a gas that our body produces on its own. It is a vasodilator as it causes the blood vessels to relax and expand, allowing for greater transmission of blood flow. This helps deliver more oxygen and nutrients to your muscles when you exercise, which can help you perform better and work out longer. 

Since vasodilators help to widen our blood vessels, nitric oxide supplements are also taken to treat heart conditions and erectile dysfunction. As nitric oxide helps improve blood pressure, it may help reduce your risk for heart disease, especially for people who do not exercise regularly. For these people, an increase in L-arginine may promote vasodilation that may not occur without exercise. 

Nitric oxide production is hindered in people with Type II diabetes, which diminishes the health of their blood vessels. This increases the risk of heart disease and high blood pressure. This may the reason why people with Type II diabetes are told to supplement with nitric oxide supplements.

Here's the catch when you take nitric oxide supplements Nitric oxide supplementation involves the precursor molecules L-arginine and L-citrulline. Precursors are compounds involved in the creation of another compound - nitric oxide in this case.  Nitric oxide supplements provide the body with the building blocks for nitric oxide production.

Nitric oxide supplements cannot contain nitric oxide because it is only available in gas form. Nitric oxide is chemically made in our bodies from L-arginine (an essential amino acid) and this is why all nitric oxide supplements contain L-arginine and L-citrulline. These supplements do not actually contain nitrous oxide, they are hoping that the extra L-arginine and L-citrulline consumed can be converted to nitrous oxide chemically in our tissues.

Note that our bodies usually makes enough L-arginine on its own. L-arginine is found in fish, meat, beans and dairy. Vegetables like beetroot and leafy greens (spinach and arugula) are rich in nitrates and can contribute to higher nitric oxide levels in the body. This is why many studies have studied whether drinking beetroot juice leads to increased performance enhancement in sports.

What exactly can nitric oxide supplements do? Since the supplements are supposed to increase nitric oxide in your body, it can potentially  help heart health, exercise performance and even treating erectile dysfunction. 

While nitric oxide is essential for vasodilation, not all research support claims that L-arginine supplements produce more nitric oxide than normal dietary intake and exercise. 

Side effects of taking nitric oxide supplements are mostly gastrointestinal issues like vomiting, diarrhoea, dizziness and headaches. More serious side effects are allergic reactions and difficulty breathing.

What does the evidence says? Some research shows improved fitness performance for runners, cyclists and swimmers although other research shows little to no effect. 

Another published systematic review and meta-analysis related to the effects of taking nitric oxide supplements regarding exercise performance concluded that nitric oxide supplements may "improve tolerance" to aerobic and anaerobic exercise in people who are not in shape or who are moderately trained. However there seems to be no benefit in highly trained people. More research is needed to show whether these supplements help improve sporting performance.

If you're still game to try, note that doses of 6 to 13 grams are usually the doses taken in studies and this seems to be well tolerated by most people.Those who are diabetic, have high blood pressure, heart problems or any other health conditions, may want to consult their doctor before starting.

References

Bescos R,  Sureda A, Tur JA et al (2012). The Effect Of Nitric-oxide-related Supplements On Human Performance. Sp Med. 42(2): 99-117. DOI: 10.2165/11596860-000000000-00000.

Gallo L, Percoraro S, Sarnacchiaro P et al (2020). The Daily Therapy With L-arginine 2,500 Mg And Tadalafil 5 Mg In Combination And In Monotherapy For The Treatment Of Erectile Dysfunction: A Prospective, Randomized Mutixenter Study. Sex Med. 8(2): 178-185. DOI: 10.1016/j.esm.2020.02.003.

MaMahon NF, Leveritt MD and Pavey TG. (2017). The Effect Of Dietary Nitrate Supplementation On Endurance Exercise Performance In Healthy Adults: A Systematic Review And Meta-analysis. Sports Med. 47(4): 735-756. DOI: 10.1007/s40279-016-7.