Do Nitric Oxide Supplements Work? An Evidence-Based Review


Nitric oxide supplements are sold like they’re as good as steroids but what does the research say? Worthwhile or worthless? Read on to find out.


Do you want rock-freaking-hard biceps and boners!?

How about shirt-ripping workout pumps that make the ladies squirm and fellas burn!?!

And what about massive, head-turning muscles that pulsate with veins so thick you could use them for surgical tubing!?!?!?!

Well, today’s your lucky day, Broseidon. A bunch of super-powerful scientists have descended from the heavens to deliver the secret to swole to us musclebound idiots.

It’s called nitric mothafuckinoxide and it’s so damn good at hacking your biology and force-feeding your muscles nutrients and hormones and shit that it was given a Nobel Prize!

That was basically copy and pasted from a sales page for a popular nitric oxide supplement.

Okay…I…touched it up a little. But not much.

Shenanigans aside, there’s no denying that nitric oxide supplements are extremely popular. Guys and gals spend tens of millions of dollars on them every year in hopes of building muscle and strength faster.

But do they work? Or are they a waste of money like most other bodybuilding supplements?

Let’s find out. Bro.

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What Are Nitric Oxide Supplements?

The first thing you need to know about these supplements is they don’t contain nitric oxide, which is a gas.

Instead, most contain as their primary ingredients one or more forms of the amino acid arginine (with arginine alpha-ketoglutarate being the most popular).

This amino acid is supposed to boost nitric oxide levels in the blood, which in turn is supposed to increase your muscle growth, strength, and performance.

What does the research say, though?

The (Apparent) Benefits of Nitric Oxide Supplements

Most nitric oxide supplements are sold first and foremost as potent muscle builders.

To that end, supplement marketers often cite research showing that arginine supplementation can raise nitric oxide levels in the body, which widens blood vessels and improves blood flow.

This blood flow mechanism has been shown to improve exercise performance in patients with cardiovascular disease and improve endothelial health (the endothelium is the lining of the blood vessels).

Increasing blood flow to the muscles also increases nutrient delivery, which has been shown to elevate protein synthesis rates. This is why arginine and nitric oxide supplements in general are often marketed like they’re natural steroids.

Another mechanism of arginine touted as a clincher is its ability to raise growth hormone production in response to exercise. This is music to the average consumer’s ears, who is indoctrinated to believe that more growth hormone of any kind and amount is going to help them build more muscle.

This all sounds pretty sexy, but look a bit closer and you start noticing flies in the soup.

Let’s tackle the growth hormone claims first because they’re 100% bogus.

Yes, supplements that increase nitric oxide levels like arginine and citrulline can increase growth hormone levels when you exercise, but no, this isn’t going to help you build more muscle.

The long story short is this: growth hormone has potent anticatabolic effects but doesn’t stimulate the growth of skeletal muscle and doesn’t increase strength. And I’m referring to dramatically spiking hormone levels by directly injecting GH, not taking a supplement that weakly augments natural production for an hour or less.

And just to drive a final nail in the growth hormone coffin, let’s take a look at an interesting study conducted by scientists at McMaster University with young, resistance trained men.

The subjects lifted 5 times per week for 12 weeks and followed a standard dietary protocol (high-protein intake, post-workout nutrition, etc.).

The primary finding of the study was that the exercise-induced spikes in anabolic hormones like testosterone, growth hormone, and IGF-1, which all remained within physiological normal ranges, had no effect on overall muscle growth and strength gains.

That is, all subjects made gains in muscle, but the variations in the size of the hormone spikes among them had no bearing on the results.

The key takeaway here is not that you should take steroids, but that things you can do to naturally raise your anabolic hormone levels are unlikely to affect your muscle growth.

And in case you’re wondering why growth hormone has become so popular in the world of bodybuilding if it doesn’t help you build muscle, it seems to greatly enhance muscle growth when combined with regular (and dangerous) use of insulin and large doses of anabolic steroids.

So, with nitric oxide’s growth hormone mechanisms brought into line, let’s move on.

The big problem with arginine as a nitric oxide booster and ergogenic aid is its unreliability. That is, it works for some people but not others.

This explains why nitric oxide supplements are very hit-and-miss–some swear by the bigger pumps and better workouts and others notice absolutely nothing.

The best that can be said about arginine is if you take enough (6 to 10 grams), it may or may not help you get more out of your workouts.

Not very exciting, I know. And that’s why I don’t recommend arginine supplementation for workout purposes.

Instead, I recommend and personally use the amino acid citrulline instead.

Citrulline is turned into arginine in the kidneys and results in larger and longer elevations of plasma arginine levels than supplementation with L-arginine itself. It also elevates plasma levels of another amino acid, ornithine, which reduces exercise-induced fatigue.

This is why research shows citrulline can reliably improve exercise performance and reduce fatigue and muscle soreness.

If you want to try citrulline for yourself, check out my 100% natural pre-workout supplement PULSE. It contains 8 grams of citrulline malate in every serving along with clinically effective dosages of 5 other ingredients proven to increase physical and mental performance.

The Bottom Line on Nitric Oxide Supplements

Research clearly shows that raising plasma nitric oxide levels can improve workout performance. Supplements that accomplish this are worthwhile additions to your regimen if you’re looking to maximize performance.

That said, the benefits of nitric oxide supplements are often oversold. They aren’t going to skyrocket strength or help you pack on mass like steroids.

A more realistic view is if a nitric oxide supplement can help you train harder over many workouts, and if you actually take advantage of this by pushing yourself in your training, you can make more progress than if you hadn’t taken it.

If you want to see what a nitric oxide supplement can do for you, go with citrulline instead of arginine. Take a clinically effective dosage of 6 to 8 grams per day and you should improvements in your workouts within a week.


What’s your take on nitric oxide supplements? Have anything else to share? Let me know in the comments below!

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I'm Mike and I'm the creator of Muscle for Life and Legion Athletics, and I believe that EVERYONE can achieve the body of their dreams.

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