A trend among athletes and bodybuilders involves taking nitric-oxide-boosting supplements to cause vasodilation, or widening of the blood vessels. BSN Nitrix is one such supplement. Its main active ingredient is L-arginine, a nitric-oxide precursor. Although Nitrix's creators and many of its consumers claim to have experienced positive results, clinical studies of L-arginine supplements suggest that this may be the placebo effect at work.
Function
BSN markets Nitrix as a vaso-muscular volumizer and says it maximizes muscle gain by boosting nitric oxide, or NO, in the blood. Nitrix contains L-arginine alpha ketoglutarate, or AAKG, which converts to NO in your body. An increased NO level is said to dilate your blood vessels, allowing nutrients to reach your muscles faster. This, in turn, is said to result in a swifter increase in muscle mass and strength.
Comparison
BodybuildingForYou.com compared Nitrix with one of its competitors, NO-xplode, and concluded that there was no difference in their muscle gain results. It noted that Nitrix contains very little besides AAKG and a controlled-release additive, whereas NO-xplode contains additional NO-boosting ingredients plus energy-boost components.
Effectiveness
Nutrition researcher and strength coach David Barr argues that studies don't support the claims made about Nitrix and other AAKG supplements. Oral arginine supplements, he says, don't affect blood flow; instead, it's 30 g intravenous arginine that's associated with vasodilation. That's a much higher dosage than you could take by mouth. In fact, you would need to take 43 g of AAKG orally to get the same effect as 30 g by IV. For comparison, one serving of three Nitrix tablets contains 3 g of L-arginine, which BSN directs you to take three times a day for a total of 9 g.
"Primer" magazine points out that clinical studies demonstrate no statistically significant difference between taking AAKG supplements and drinking an energy drink.
In September 2010, the "Journal of the International Society of Sports Nutrition" published the results of a study in which subjects participated in a seven-day regimen of exercise and AAKG or placebo supplementation. Compared to the placebo, the supplement increased L-arginine levels in the blood but demonstrated no increase in brachial artery blood flow or nitric oxide levels. Instead, researchers attributed the increased blood flow and NO levels in both the placebo-taking and supplement-taking groups to resistance exercise.
Side Effects
Barr states that you couldn't take large quantities of arginine orally because it would make you sick to your stomach. He cites a study showing that 10 g doses correlate with gastric upset, and another in which oral arginine caused such gastric distress that researchers had to reduce the dosage in order to finish the study. Even at the lower dose, subjects reported intestinal cramping and diarrhea.
Warning
A study published in June 2010 in the "Journal of the International Society of Sports Nutrition" warned that growing interest in nitric-oxide precursors may lead users to unwise choices. Sodium nitrate, taken as a supplement to boost nitric oxide, has led to fatalities. Nitrix does not contain sodium nitrate, but incautious Nitrix consumers could conclude that one vasodilator is much like another, leading them to take a more dangerous product as a Nitrix alternative.
References
- Bodybuilding-Help.com: BSN Nitrix
- SupplementCritic.com: BSN Nitrix Reviews
- "Primer" Magazine: Straight Talk on Supplements--BS or the Real Deal?
- David Barr: Consumer Alert -- The NO2/Arginine Scam
- Journal of the International Society of Sports Nutrition: Effects of 7 Days of AAKG Supplementation
- Journal of the International Society of Sports Nutrition: Potentially Fatal New Trend
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