I wrote a review of nitric oxide boosters a while back. Here is a summary of that research:
*Actual research/testing of these NO supplements is “non-existent.”
*The primary ingredient of most NO supplements is L-arginine, which most of us already get plenty of through diet.
*Supplement companies often quote inappropriate research:
1. The dosage (of L-arginine, for example) are often much lower in NO supplements vs research.
2. The route of administration in much of the research was intravenous—not oral.
*The “pump” some get through NO supplements is likely caused by the sugar, which itself has a vasodilating effect.
*The only dietary supplement which has be scientifically proven to increase NO levels is Glycine Propionyl-L-Carnitine (GPLC). More research is needed to understand its usefulness for fitness/exercise.
A new study has come out, and here are the findings:
We compared Glycine Propionyl-L-Carnitine (GlycoCarn(R)) and three different pre-workout nutritional supplements on measures of skeletal muscle oxygen saturation (StO2), blood nitrate/nitrite (NOx), lactate (HLa), malondialdehyde (MDA), and exercise performance in men. Methods: Using a randomized, double-blind, cross-over design, 19 resistance trained men performed tests of muscular power (bench press throws) and endurance (10 sets of bench press to muscular failure). A placebo, GlycoCarn(R), or one of three dietary supplements (SUPP1, SUPP2, SUPP3) was consumed prior to exercise, with one week separating conditions. Blood was collected before receiving the condition and immediately after exercise. StO2 was measured during the endurance test using Near Infrared Spectroscopy. Heart rate (HR) and rating of perceived exertion (RPE) were determined at the end of each set. Results: A condition effect was noted for StO2 at the start of exercise (p=0.02), with GlycoCarn(R) higher than SUPP2. A condition effect was also noted for StO2 at the end of exercise (p=0.003), with SUPP1 lower than all other conditions. No statistically significant interaction, condition, or time effects were noted for NOx or MDA (p>0.05); however, MDA decreased 13.7% with GlycoCarn(R) and increased in all other conditions. Only a time effect was noted for HLa (p<0.0001), with values increasing from pre- to post-exercise. No effects were noted for HR, RPE, or for any exercise performance variables (p>0.05); however, GlycoCarn(R) resulted in a statistically insignificant greater total volume load compared to the placebo (3.3%), SUPP1 (4.2%), SUPP2 (2.5%), and SUPP3 (4.6%). Conclusion: None of the products tested resulted in favorable changes in our chosen outcome measures, with the exception of GlycoCarn(R) in terms of higher StO2 at the start of exercise. GlycoCarn(R) resulted in a 13.7% decrease in MDA from pre- to post-exercise and yielded a non-significant but greater total volume load compared to all other conditions. These data indicate that 1) a single ingredient (GlycoCarn(R)) can provide similar practical benefit than finished products containing multiple ingredients, and 2) while we do not have data in relation to post-exercise recovery parameters, the tested products are ineffective in terms of increasing blood flow and improving acute upper body exercise performance.
Quoted from the Journal of the International Society of Sports Nutrition (emphasis mine).
So let’s review the main points:
*With the exception of GlycoCarn (Glycine Propionyl-L-Carnitine), NONE of the NO supplements used did much of anything.
*None of the products (including GlycoCarn) significantly improved blood flow or performance.
I still see no compelling reason to spend money on “nitric oxide boosters” for the goal of building muscle or increasing strength.
Note: I do think L-arginine may have potential to improve sexual health when combined with other supplements.
I believe learning how to eat and train are much more important than supplements. Check out some of my recommended programs if you are wanting to build muscle.