For nitrate endurance boost, stick to beet juice and avoid supplements

I’ve blogged a bunch of times this year about the incredible performance-boosting effects of juice; studies showing that it’s the nitrates in beet juice that are responsible; and further studies exploring how nitrate from beets is converted (by bacteria in your mouth) to nitrite, and then to nitric oxide, which is where all the magic happens. This has led to all sorts of questions, like (a) aren’t nitrates, as found in hot dogs and so on, really bad for you?, and (b) can I just take a nitrate supplement instead of drinking all that beet juice that turns the toilet a funny colour?

The answer to the first question is, well, I don’t know — but scientists are definitely rethinking the idea that nitrates are a big villain. Stephan Guyenet had a good blog post that explored some of this change in thinking.

As for the second question, there’s a series of letters to the editor in the current issue of the Journal of Applied Physiology that should make you think twice before considering supplementing. The first is from a group of Swedish researchers who have pioneered some of the research into the health benefits of nitrates. They basically suggest that direct supplementation of nitrate (in the form of nitrate salt) is probably okay (it’s “nontoxic even in higher doses”), because the body can only convert it slowly to nitrite through the help of friendly mouth bacteria. But taking nitrite supplements directly has a toxicity comparable to cyanide — and there’s great potential for confusion, according to the researchers:

A case of unintentional ingestion of nitrite by an athlete was recently reported on a runners’ internet forum. The subject had taken a nitrite salt before exercise in the belief that it was nitrate, and he developed symptoms suggestive of methemoglobinemia.

They also point out that “organic nitrates and nitrites, for example nitroglycerine and amyl nitrite” can be fatal at too high a dose. The bottom line, they say:

In summary, at this time we advise athletes to refrain from the uncontrolled use nitrate and nitrite salts as dietary supplements. While the acute toxicity of nitrate is very low or absent, any confusion leading to a large unintentional intake of nitrite or organic nitrates and nitrites is potentially life threatening. In contrast, with natural sources of nitrate such as whole vegetables or vegetable juices, we do not foresee any acute risks.

There are a couple of letters in response from beet juice researchers, and they’re basically in agreement. To paraphrase very roughly, they basically say “Yes, taking nitrites would be a really dumb thing to to do, so stick with whole fruits and vegetables as a nitrate source.”

Having read all of that, it’s still not entirely clear to me if there’s a problem with taking nitrate salt. However, my confusion on that point is precisely the point, I guess: if nitrites and organic nitrates are potentially very dangerous, it’s best not to mess around if you’re not absolutely sure you’ve got the right stuff. Stick with the beets.