One of my favorite running trails in the early spring.
When you’re a runner, you’re always looking for that special something to give you that “edge”, to improve speed and/or endurance. There’s no shortage of nutrients, herbs, and even drugs to choose from. Overwhelmingly, most are not proven to work, but that doesn’t stop many runners from taking even the ones that science shows are useless. Now this may be a little different for vegan runners. Some nutrients that meat-eating athletes take for granted like iron, zinc, or possibly creatine may help improve athletic performance in vegans since these nutrients aren’t as plentiful in plant foods or are harder to absorb from them.
It is possible that this is the case with arginine, a “conditionally” nonessential amino acid, which means it is essential for some people or essential some of the time for most people. I know, it’s a bit confusing! This is in contrast to the 9 essential amino acids that are essential no matter what. For more information on the differences between essential and non-essential amino acids please read: Amino Acids.
There’s some evidence that vegetarians tend to run a little low on arginine compared to meat-eaters: Plasma homocysteine levels in Taiwanese vegetarians are higher than those of omnivores.
Now like I said before, it is possible that some nutrients may benefit vegetarians, especially vegans, but not meat-eaters and this may be the case with arginine for reasons cited above. I tried to see if I could find any studies that looked into this specific question, if arginine could benefit vegetarian athletes. I couldn’t, but here are some studies that looked into arginine in general.
According to Eur J Appl Physiol. 2013 Jul in No effect of acute L-arginine supplementation on O₂ cost or exercise tolerance:
In conclusion, acute dietary supplementation with ARG or ARG + CHO did not alter biomarkers of NO synthesis, O₂ cost of exercise or exercise tolerance in healthy subjects.
It doesn’t appear to be useful based on this.
This study came to a different conclusion. According to J Strength Cond Res. 2010 May;24 in: Effects of arginine-based supplements on the physical working capacity at the fatigue threshold:
These findings supported the use of arginine-based supplements, at the dosages examined in the present investigation, as an ergogenic aid for untrained individuals.
According to the second study, it did help, although they may have been measuring things a little different. Both studies were small studies, though the second was the larger study.
What to make of this? I don’t think anyone should take arginine based on the evidence, and more research obviously needs to be done. Now it is possible that vegans could benefit more from arginine supplementation, but this is speculation on my part. Based on my readings, it may be potentially harmful to take one isolated amino acid in large amounts since this could displace other important amino acids.
Since there’s plenty of vegan runners out there that take no arginine supplements and show no acute arginine deficiency symptoms, I really do not believe supplemental arginine is necessary. If you’re a vegan, eat as many different types of legumes, vegetables, fruits, and whole grains as you can, to make sure you are getting optimal amounts of all the necessary nutrients. A vegan multi-vitamin that has iron, zinc and B-12 may also be a good idea, just in case.
AcroTrekker 
It’s a good point! I’m strictly vegetarian and almost vegan myself (I do bend the vegan – but not vegetarian – rules a little when going out with friends, as it’s just too limiting when eating out, but at home I’m completely vegan, too!). I don’t take any supplements, and just rely on a balanced diet. Having said that, I do make sure that my soy milk is fortified with vitamin B12, which I think is important. =)
I’m often surprised by near vegans who don’t take supplements. At least you get B-12 from fortified foods. I have to take zinc and iron supplements, it seems my body can’t absorb them from plant foods. Good luck with your race.
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” L-arginine is converted in the body into a chemical called nitric oxide. Nitric oxide causes blood vessels to open wider for improved blood flow. L-arginine also stimulates the release of growth hormone, insulin, and other substances in the body,” according to Rx List. If this is so, why isn’t it useful to any athlete, whether vegan or not?
Of course it is “useful”, in the sense that our bodies need it and will use it. However, if a person isn’t deficient in it, and/or they are getting an optimal amount, it is unlikely that supplementation will be beneficial. The same could be said for vitamin C or even for getting adequate carbohydrate before exercise or any nutrient for that matter. We can only use or metabolize only so much, so there are diminishing returns beyond a certain amount. More isn’t necessarily better.
Maybe arginine would be more useful for vegans, since there is evidence many of them may not be getting enough. I would love to see studies done on this. Thanks for your input, Tony!