If you’re striving for that unmistakably satisfying muscle pump, the best nitric oxide supplements can help you achieve that full, swollen feeling that makes a good workout even more rewarding. Designed to support improved blood flow and better oxygen delivery to your muscles, these products tend to be a bit misunderstood.
In this guide, I’ll break down their key ingredients, research-backed benefits, and what to look for in a high-quality nitric oxide supplement. So, whether you want to leave the gym looking extra vascular after you lift or you want to reap the potential endurance rewards during your cardio sessions, let’s dive right in.
Key Takeaways
Nitric oxide supplements work by supplying your body with key precursor ingredients like L-citrulline and nitrates that it converts into nitric oxide for vasodilation and improved blood flow.
The main benefit during training is enhanced muscle pump, better oxygen delivery to working muscles, and improved endurance in higher-rep or cardiovascular work.
L-citrulline is significantly better absorbed than L-arginine for nitric oxide production and should be the primary ingredient in any quality NO supplement.
Stimulant-free NO supplements like AlphaSurge Pump Shot are ideal for stacking with your existing pre-workout or for those who want pump support without more caffeine.
As always, consult with your healthcare provider before starting any new supplement or nutrition program, especially if you are pregnant, nursing, taking medication, or have a medical condition.
Table of Contents:
- What Is Nitric Oxide and Why Does It Matter for Training?
- How Nitric Oxide Supplements Work
- Best Nitric Oxide Supplement Ingredients
- Nitric Oxide Supplements Benefits
- How to Choose the Best Nitric Oxide Supplement
- The Bottom Line on Nitric Oxide Supplements
- Frequently Asked Questions
What Is Nitric Oxide and Why Does It Matter for Training?
Before diving into ingredients and supplements, let's start with the basics: What is nitric oxide? In short: it’s a signaling molecule that causes blood vessels to relax and dilate, increasing blood flow to muscles during training. This improves nutrient and oxygen delivery and produces the muscle pump feeling that many lifters (myself included) love to see and feel.
Although your body naturally produces nitric oxide, its effects become especially noticeable during exercise. When nitric oxide levels increase, your blood vessels widen through a process called vasodilation (1). When this occurs, blood can travel to your muscles more efficiently, delivering oxygen and nutrients that help support performance during strenuous workouts.
As a former rugby player and longtime weightlifter, I can attest that this increased blood flow can have positive physical and mental effects when you’re training. On one hand, that full, tight, skin-splitting sensation often referred to as a “pump” can provide an extra layer of motivation. Strength athletes, bodybuilders, and even casual lifters should be familiar with this aesthetic benefit.
However, improved blood circulation can also support endurance and exercise capacity. More efficient blood flow means oxygen can reach your muscles more effectively, which can be particularly beneficial during high-repetition workouts such as CrossFit or high-intensity interval training (HIIT).
How Nitric Oxide Supplements Work
Contrary to popular belief, nitric oxide supplements do not contain NO directly. Instead, they provide precursor compounds like L-citrulline and nitrates that your body converts into nitric oxide through enzymatic pathways.
That distinction matters because nitric oxide isn’t something you can literally scoop out of a tub. It’s a short-lived gas produced in the body. So, supplements in this category don’t deliver this substance directly. Instead, they support the pathways your body already uses to produce it.
You can view nitric oxide supplementation like providing the raw materials for a construction project. The key ingredients (more on that later) are like the bricks, but your body still has to do the building through its natural processes.
However, it’s important to point out that just because you add a nitric oxide supplement to your routine doesn’t guarantee improved performance or a ripped physique. You must still prioritize sleep, nutrition, hydration, and training. But for both strength and endurance athletes, these supplements can support increased blood flow, a stronger pump, improved oxygen delivery, and better recovery (2).
Best Nitric Oxide Supplement Ingredients
The most effective nitric oxide supplement ingredients are L-citrulline, L-citrulline malate, dietary nitrates from beetroot, and glycerol for hyperhydration-based pumps. Here’s a brief overview of how each one works:
L-Citrulline
L-Citrulline is a naturally occurring amino acid commonly found in clean pre-workout formulas that is converted first into L-arginine, then ultimately into nitric oxide. In addition to its pump-enhancing effect, L-citrulline can also reduce perceived exertion and post-exercise muscle soreness (3).
L-Citrulline Malate
Citrulline malate combines L-citrulline with malic acid, an organic compound found in a variety of fruits and vegetables. Research suggests that citrulline malate enhances athletic anaerobic performance and relieves muscle soreness (4).
Dietary Nitrates
Along with leafy greens, beetroot is one of the most popular natural sources of dietary nitrates. When consumed, these compounds are converted into nitric oxide via a separate pathway from citrulline and arginine.
Glycerol
A sugar alcohol that serves as an essential building block for triglycerides, glycerol is highly hygroscopic, which means it retains moisture. In the context of nitric oxide supplements, it acts as an osmotic agent by drawing water into the bloodstream and muscles (5). This can help deliver that dense, full muscle pump.
| Ingredient | How It Works | Effective Dose |
|---|---|---|
| L-Citrulline | Increases nitric oxide production through arginine conversion | 6-8 grams |
| Citrulline Malate | Provides citrulline plus malic acid | 8 grams |
| Dietary Nitrates | Converts to nitric oxide through the nitrate pathway | Varies |
| Glycerol | Supports cellular hydration and muscle pump | 1-3 grams |
Nitric Oxide Supplements Benefits
The primary benefits of nitric oxide supplements include greater muscle pump, improved blood flow and oxygen delivery during training, enhanced endurance in high-rep sets, and faster recovery between sets. Let’s touch upon each of those so you can understand why you may want to add this supplement to your stack.
Greater Muscle Pump
The most tangible nitric oxide supplement benefit is an enhanced muscle pump. By promoting vasodilation, more blood can reach your working muscles during exercise, resulting in that full, tight feeling that’s synonymous with a successful training session. Of course, achieving a pump doesn’t necessarily mean that you’re building muscle, but it may provide a psychological boost that pushes you to train harder. Plus, who doesn’t want to see their veins and muscles popping?
Improved Blood Flow and Oxygen Delivery
Nitric oxide’s primary function is to allow your blood vessels to relax and widen, thereby improving your body’s ability to circulate and deliver oxygen and nutrients. Whether you’re working on your cardiovascular conditioning or engaging in resistance training, this enhanced blood flow and oxygen delivery can support better overall performance.
Enhanced Endurance
By extension, this improved blood flow can have a positive impact on your endurance. Research on ingredients like L-citrulline and dietary nitrates suggests they can help reduce fatigue and your rate of perceived exertion (often referred to as RPE) and improve your exercise efficiency. For this reason, many cyclists and runners utilize nitric oxide boosters.
Faster Recovery
Despite being mostly associated with muscle pumps, dietary nitrates may also support recovery in certain conditions. Research shows they can accelerate post-exercise muscle metabolic recovery when training in low-oxygen environments, such as at altitude (6).
How to Choose the Best Nitric Oxide Supplement
Look for a product with at least 6g of L-citrulline per serving, a transparent label, and no unnecessary fillers. Project-1 meets those thresholds while also delivering 200 milligrams of caffeine per serving.
However, if you already use caffeine in a separate pre-workout, you may want to opt for a stimulant-free formula so you don’t exceed the common caffeine intake recommendation of 400 milligrams. If you’re looking for a stim-free glycerol pump option, AlphaSurge Pump Shot is a wise choice, as it delivers a loaded dose of nitric oxide precursors in a pre-workout liquid shot format.
Available in three flavors, it can help support:
- Nitric oxide production
- Oxygen & nutrient delivery
- Muscle cell volumization (aka the pump)
- Training performance
- Muscular endurance*
Whether you take it standalone or stack it with your regular pre-workout, AlphaSurge is built to amplify the pump without adding any stimulants to your regimen.
The Bottom Line on Nitric Oxide Supplements
When it comes to the best nitric oxide supplements, you should ensure there’s an evidence-backed dose of L-citrulline (6 grams), as it’s considered the gold standard compound for supporting nitric oxide production. Because of its ability to support enhanced pumps and blood flow, L-citrulline is a staple ingredient in many pre-workout supplements, including Project-1. Meanwhile, AlphaSurge Pump Shot contains glycerol, agmatine sulfate, and L-norvaline as its pump-enhancing ingredients.
While the former contains 200 mg of caffeine per serving, the latter is stim-free, making it a viable option whether you train in the morning or at night. Ultimately, adding a nitric oxide supplement won’t magically make your biceps grow or turn you into a marathon runner, but it can support enhanced blood flow, oxygen delivery, and other physiological processes that contribute to better performance.
Frequently Asked Questions
Does nitric oxide help with muscle growth?
Nitric oxide does not directly build muscle. However, consistent use may support growth over the long haul by enhancing blood flow, nutrient delivery, and workout performance when combined with proper nutrition and resistance training protocols.
When should I take a nitric oxide supplement?
Most nitric oxide supplements should be taken about 30 minutes before your workout. Check the label for the manufacturer’s serving instructions, as this can vary.
Is L-citrulline the same as a nitric oxide supplement?
No, L-citrulline is a commonly used ingredient in several types of supplements, including pre-workout formulas like Project-1.
Can I take a nitric oxide supplement with a stimulant pre-workout?
Yes, you can pair this supplement with a caffeinated pre-workout to enhance muscle pumps and blood flow without increasing your overall caffeine intake.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
References:
(1) Chen, K., Pittman, R. N., & Popel, A. S. (2008). Nitric oxide in the vasculature: where does it come from and where does it go? A quantitative perspective. Antioxidants & redox signaling, 10(7), 1185–1198. https://doi.org/10.1089/ars.2007.1959
(2) Kiani, A. K., Bonetti, G., Medori, M. C., Caruso, P., Manganotti, P., Fioretti, F., Nodari, S., Connelly, S. T., & Bertelli, M. (2022). Dietary supplements for improving nitric-oxide synthesis. Journal of preventive medicine and hygiene, 63(2 Suppl 3), E239–E245. https://doi.org/10.15167/2421-4248/jpmh2022.63.2S3.2766
(3) Rhim, H. C., Kim, S. J., Park, J., & Jang, K. M. (2020). Effect of citrulline on post-exercise rating of perceived exertion, muscle soreness, and blood lactate levels: A systematic review and meta-analysis. Journal of sport and health science, 9(6), 553–561. https://doi.org/10.1016/j.jshs.2020.02.003
(4) Pérez-Guisado, J., & Jakeman, P. M. (2010). Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness. Journal of strength and conditioning research, 24(5), 1215–1222. https://doi.org/10.1519/JSC.0b013e3181cb28e0
(5) van Rosendal, S. P., & Coombes, J. S. (2012). Glycerol use in hyperhydration and rehydration: scientific update. Medicine and sport science, 59, 104–112. https://doi.org/10.1159/000341959
(6) Vanhatalo, A., Jones, A. M., Blackwell, J. R., Winyard, P. G., & Fulford, J. (2014). Dietary nitrate accelerates postexercise muscle metabolic recovery and O2 delivery in hypoxia. Journal of applied physiology (Bethesda, Md. : 1985), 117(12), 1460–1470. https://doi.org/10.1152/japplphysiol.00096.2014
