NitraFlex is a testosterone, nitric oxide, and focus boosting pre-workout supplement designed to allow users to surpass previous training plateaus and pack on muscle.
“This new breed of concentrate is an annihilating force to reckon with. So illicitly strong, it may become extinct,” says one advertisement.
These claims are bold, so I took a closer look at the ingredients to see if they are clinically proven.
What’s Under the Lid?
NitraFlex comes in powder and capsule form and its ingredients are featured in a proprieceutical (proprietary + nutraceutical) blend. Both forms contain the same ingredients; however, the powder contains additional 325 mg caffeine per serving.
With the exception of caffeine, amounts for the remaining ingredients in both products are not provided. Consequently, it is impossible to know if amounts in NitraFlex are clinically effective.
Here is a look at some of the key ingredients:
This ingredient is also known as citrulline. This amino acid is an L-arginine precursor. Hence, it influences nitric oxide production, a compound that enhances blood flow by widening blood vessels.
However, excessive arginine amounts stimulate arginase activity, an enzyme that destroys arginine. Citrulline is not metabolized in the liver or intestine and does not induce arginase, “but rather inhibits its activity.” Research shows citrulline enters kidney, vascular endothelium and other tissues to raise L-arginine and boost NO levels. 
Research shows 6 g citrulline before exercise increased urea, nitrate (“indicative of nitric oxide”), and growth hormone. 
Also known as L-arginine, 2-Amino-5-guanidinopentanoic acid converts to nitric oxide to improve athletic performance.
One study shows 6 g arginine for 3 days enhanced nitric oxide production and improved time to exhaustion (24.8%) when compared to a placebo. 
Arginine alpha-ketoglutarate is said to enhance blood flow, arginine, and nitric oxide metabolites. However, studies supporting its benefits are weak.
One study shows an arginine alpha-ketoglutarate-based supplement increased plasma arginine levels combined with resistance exercise.. But, researchers indicate the brachial-artery blood flow and nitric oxide metabolite effects “can only be attributed to the resistance exercise.” 
This ingredient is better known as beta alanine. Beta alanine enhances muscular endurance by boosting carnosine production. Carnosine buffers lactic acid to reduce muscle fatigue.
One study shows 4.8 g beta alanine per day over a 4-week period increased carnosine content and enhanced fatigue attenuation during repeated bouts of exhaustive dynamic contractions. 
2-Amino-4-(Ethylcarbamoyl) Butyric Acid
Another name for this ingredient is theanine. Theanine is used to reduce psychological and physiological stress and increase relaxation.
One study shows stress, heart rate, and anxiety that occurred during placebo administration was attenuated with 200 mg L-theanine. 
However, another study analyzed theanine and benzodiazepine anxiolytic alprazolam’s independent effects on anticipatory anxiety after acute usage. Both failed to modify these parameters, but theanine was shown to “have some relaxing effects under resting conditions.” 
Calcium Fructopyranose Borate
Borates are names for oxyanions that contain boron and oxygen. Boron is known to influence testosterone levels.
One study analyzed consumption of 10 mg boron with breakfast for 7 days. Research reveals boron increased plasma free-testosterone levels. 
What Is the Best Way to Use NitraFlex?
Directions for taking NitraFlex are different depending on whether you buy the powder or tablet form.
According to the manufacturer, NitraFlex is potent, so users need only take 1 scoop (1 serving) with 6-8 oz. water before working out. Though the manufacturer doesn’t specify how long before working out NitraFlex needs to be taken, third party retailers like BodyBuilding.com mention it should be taken around 30 minutes prior.
It is recommended users start with a lower dose (1/2 serving) to assess tolerance. If users respond favorably, the dose may be increased to a full serving.
NitraFlex tablet doses are different depending on user’s weight.
Users under 200 lbs. take 3-4 tablets three times a day on an empty stomach.
Users over 200 lbs. take 5-6 tablets three times a day on an empty stomach.
Tolerance should be assessed with the tablets as well. Take smaller doses in the beginning to assess its benefits. If responding well, increase tablets to recommended servings per day.
Are There Side Effects?
The company doesn’t specify whether there are side effects associated with NitraFlex.
However, side effects may occur such as stomach irritation, nervousness, insomnia, nausea, and increased heart rate and respiration due to caffeine content. 
Side effects of arginine include abdominal pain, bloating, diarrhea, allergies, airway inflammation, and blood abnormalities. 
It is difficult to tell whether users will experience these side effects because I am unsure how much of these ingredients are found in NitraFlex.
Are Users Satisfied?
Several users review their NitraFlex experience on third party retail websites. The powder receives an awesome 9 out of 10 rating on BodyBuilding.com and the tablets receive an overall 4.9 out of 5 star review on Amazon.com. Here is what some users are saying:
“Amazing pump, amazing strength gains and amazing focus,” says DuranBrother69 on BodyBuilding.com. “Although, green apple I find was very bitter/sour, would not recommend green apple.”
Another Bodybuilding.com user, BHeath11, says, “By far the best pre-workout I have ever taken! Always gets me hyped for my workouts. Unlike other pre-workouts I have taken, this one seems to have the longest and by far strongest effect!” He mentions his skin broke out into a red rash after use but it wasn’t severe and was gone before his workout was over.
“Amazing pre workout!!!” exclaims Getswole on Amazon.com. “Best pumps I have ever had from a product, no crash from energy and insane vascularity. Tastes amazing and digests well!!!”
Dwayne says, “It’s the only pre-workout I’ve used that seems to be effective and actually gives me those few extra meaningful reps. Read all the reviews you want but this pre-workout is awesome!”
Where Are the Best NitraFlex Deals?
One NitraFlex bottle (powder) provides 30 servings per container and is available in several flavors: Green Apple, Watermelon, Pineapple, and Fruit Punch.
One NitraFlex container (capsule) provides 60 servings.
NitraFlex is available for purchase through several websites like Amazon.com, BodyBuilding.com, VitamineShoppe.com, A1Supplements.com, and the official website, TeamGAT.com.
NitraFlex powder form retails anywhere from $28.49-$62.99, and Nitraflex tablets retail between $38.68 and $62.99.
I found the best deals through Amazon.com.
Is NitraFlex a Great Product?
It’s hard to ignore such favorable reviews surrounding both NitraFlex products on several third party retailer sites. Its ingredients are clinically proven to enhance blood flow, improve athletic endurance and focus, and boost testosterone levels.
It is moderately priced and provides a decent serving amount per container.
However, NitraFlex may not be for everyone. If you are caffeine-sensitive and interested in buying NitraFlex, I suggest trying the capsule form because it is stimulant-free.
Some users may not respond well to the ingredients based on personal tolerance. But, overall, I am convinced NitraFlex is worth checking out, especially if you are looking for a new pre-workout supplement to optimize your lifting performance.
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 Naghii Mr, et al. “Comparative effects of daily and weekly boron supplementation on plasma steroid hormones and proinflammatory cytokines.” J Trace Elem Med Biol. 2011 Jan;25(1):54-8. doi: 10.1016/j.jtemb.2010.10.001. Epub 2010 Dec 3.
 “Caffeine.” WebMD. Available from: http://www.webmd.com/vitamins-supplements/ingredientmono-979-CAFFEINE.aspx?activeIngredientId=979&activeIngredientName=CAFFEINE
 “L-Arginine.” WebMD. Available from: http://www.webmd.com/vitamins-supplements/ingredientmono-875-L-ARGININE.aspx?activeIngredientId=875&activeIngredientName=L-ARGININE