Nitric oxide is produced by nearly every type of cell in the human body and is one of the most important molecules for blood vessel health.
It’s a vasodilator, which relaxes the inner muscles of your blood vessels, causing the vessels to widen. In this way, nitric oxide increases blood flow and lowers blood pressure.
Supplements that increase nitric oxide in the body make up one of the most popular supplement categories today.
These supplements don’t contain nitric oxide itself. However, they contain compounds that your body can use to make nitric oxide and have been shown to provide many benefits for health and performance.
Here are five health and performance benefits of taking nitric oxide supplements.
1. Nitric oxide supplements help treat erectile dysfunction
Erectile dysfunction (ED) is the inability to achieve or maintain an erection firm enough for sex.
L-citrulline is an amino acid that may help treat erectile dysfunction by increasing nitric oxide production.
Nitric oxide is needed for the muscles in the penis to relax. This relaxation allows chambers inside the penis to fill with blood, so the penis becomes erect.
In one study, L-citrulline improved erection hardness in 12 men with mild erectile dysfunction.
Researchers concluded that L-citrulline was less effective than prescription drugs used to treat ED, such as Viagra. Nevertheless, L-citrulline proved to be safe and well tolerated.
Two other nitric-oxide-boosting supplements have been shown to treat erectile dysfunction — the amino acid L-arginine and French maritime pine bark extract.
In several studies, combining L-arginine and French maritime pine bark extract significantly improved sexual function in men with ED.
L-arginine and French maritime pine bark extract appear safe when taken together.
Summary: Nitric oxide plays a vital role in erectile function. Several supplements, including L-citrulline, L-arginine, and French maritime pine bark extract, have increased nitric oxide levels in men with erectile dysfunction (ED).
2. Nitric oxide supplements may decrease muscle soreness
A form of L-citrulline called citrulline malate increases nitric oxide production and decreases muscle soreness.
Muscle soreness is an uncomfortable experience that tends to occur after strenuous or unaccustomed exercise.
This soreness is delayed-onset muscle soreness and usually feels the strongest 24–72 hours after exercise.
In one study, 41 people were randomized to receive either 8 grams of citrulline malate or a placebo one hour before performing as many repetitions as possible on a flat barbell bench press.
That given citrulline malate reported 40% less muscle soreness at 24 and 48 hours after the exercise than those who took the placebo.
Citrulline malate increases nitric oxide production, which increases blood flow to active muscles. In turn, citrulline malate is thought to increase nutrient delivery and clear waste products related to muscle fatigue, such as lactate and ammonia.
However, a later study on the effects of citrulline after leg exercises did not find citrulline malate helpful for treating muscle soreness.
One explanation for this difference in findings is that the people in the leg exercise study were given 6 grams of citrulline malate, which is 2 grams less than the previous study.
Therefore, the ability of citrulline malate to decrease muscle soreness may depend on the dose and exercise. However, more research on this is needed.
Summary: Citrulline malate is a form of L-citrulline that may help alleviate muscle soreness by increasing nitric oxide. The dose and type of exercise may affect the ability of citrulline malate to decrease muscle soreness.
3. Nitric oxide supplements can lower blood pressure
People with high blood pressure are thought to have an impaired ability to use nitric oxide in their bodies.
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High blood pressure occurs when the force of your blood pushing against the walls of your arteries is consistently too high.
Over time, high blood pressure can lead to health issues such as heart disease and kidney disease.
It has been shown that a diet high in fruits and vegetables decreases blood pressure and therefore lowers the risk of disease.
This has led researchers to test the beneficial effects of certain compounds found in fruits and vegetables on blood pressure levels.
Nitrate is a compound in beetroot and dark leafy greens like spinach and arugula.
When you consume nitrate, your body converts it to nitric oxide, which causes blood vessels to relax and dilate, lowering blood pressure.
Many studies have shown nitrate may help lower blood pressure by increasing nitric oxide production.
One review analyzed the effects of nitrate supplements on adults’ blood pressure.
Six of the 13 studies analyzed found significant reductions in systolic and diastolic blood pressure when participants took nitrate supplements.
Another review of 43 studies found that participants’ systolic and diastolic blood pressures decreased by an average of 3.55 and 1.32 mm Hg, respectively, after they took nitrate supplements.
Like nitrates, flavonoid extracts have been shown to improve blood pressure.
Flavonoids have powerful antioxidant effects and are found in almost all fruits and vegetables.
Scientists believe flavonoids not only increase nitric oxide production but also decrease its breakdown, promoting higher levels overall.
However, nitrates have more research supporting their blood-pressure-lowering effects than flavonoids do.
Summary: Vegetables and fruits contain several compounds, such as nitrate and flavonoids, that may help keep blood pressure under control by increasing nitric oxide levels.
4. Nitric oxide supplements boost exercise performance
Nitric oxide is involved in many cell processes, including widening the blood vessels or vasodilation. Wider blood vessels help increase the delivery of nutrients and oxygen to working muscles during exercise, thus enhancing exercise performance.
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This has made nitric oxide supplements popular among athletes and recreational gym-goers.
These supplements often contain several ingredients that are said to increase nitric oxides, such as nitrate or the amino acids L-arginine and L-citrulline.
In many analyses, nitrate has been shown to improve exercise performance in cyclists, runners, swimmers, and even kayakers.
On the other hand, L-arginine has not proven to be effective for improving exercise performance in many studies.
This is likely because most of the L-arginine that is ingested is metabolized or broken down before it gets a chance to reach the bloodstream, whereas L-citrulline is not.
For this reason, L-citrulline is more effective than L-arginine at increasing nitric oxide and therefore exercise performance.
Summary: Supplements intended to increase nitric oxide are commonly promoted as performance enhancers. While the performance-enhancing benefits of L-arginine are minimal, nitrate and L-citrulline may be worthwhile.
5. Nitric oxide supplements may help manage type 2 diabetes
Nitric oxide production is impaired in people with type 2 diabetes.
This leads to poor blood vessel health, leading to conditions like high blood pressure, kidney disease, and heart disease over time.
Therefore, supplements that increase nitric oxide may have important implications for diabetes treatment and disease prevention.
One study found that when people with type 2 diabetes took L-arginine, their nitric oxide production increased.
This increase in nitric oxide also led to increased insulin sensitivity, allowing for better blood sugar control.
Another study of 144 people looked at the effects of L-arginine on preventing or delaying the progression of type 2 diabetes.
While L-arginine did not prevent people from developing diabetes, it increased insulin sensitivity and improved blood sugar control.
But until more research is available, it is premature to recommend taking L-arginine supplements to treat diabetes.
Summary: People with diabetes have impaired nitric oxide production, which can lead to harmful health effects. L-arginine has been shown to improve blood sugar control in people with diabetes, but more research is needed before it can be recommended.
Side effects of nitric oxide supplements
Nitric oxide supplements are generally safe when taken in appropriate amounts.
However, there are some side effects to be aware of.
L-arginine taken in doses above 10 grams can cause stomach discomfort and diarrhea.
Beetroot juice supplements can also turn your urine and stool red. This is a common but harmless side effect.
Before taking any supplements to increase nitric oxide, consult your doctor or dietitian.
Summary: Nitric oxide supplements are generally considered safe. However, some side effects include potential stomach discomfort and diarrhea, dark red stool, and urine.
Nitric oxide is a molecule that plays many vital roles in human health.
Many supplements are claimed to increase nitric oxide in the body and provide impressive benefits for health and performance.
They usually contain ingredients like nitrate or the amino acids L-citrulline and L-arginine.
However, other supplements, such as French maritime pine bark extract, have also increased or maintained nitric oxide levels.