Na & NaCl: My Mobile Nutrition Laboratory
As you know, I’ve been giving my running nutrition quite a bit of thought lately. The next few months of training runs will serve as a running laboratory for my nutrition intake, as I seek the perfect combination for my body during ultra-distances. I’ve used the pinole wafers on a few runs now, and have been pretty happy with the results, although I am going to try and make them smaller, and find ways to add a bit more flavor. However, the combination of pinole and water on my long runs got me thinking about my sodium/salt intake as well. Most electrolyte drinks and gels contain some level of sodium in order to help regulate the levels in your body. While cutting these items out to some degree is certainly lowering my sugar intake, it also has the potential to throw off my sodium balance since there is no added salt in the pinole. I am going to experiment with adding salt to the pinole to be certain, but I also started thinking and reading more about the need for added salt/sodium in my nutrition plan, and I discovered some interesting things.
First, I should note that I have been using the terms “sodium” and “salt”, but there is a difference. Some nutritional supplements will list “sodium” content, which includes sodium chloride (NACl), as well as the possibility of several other sodium containing salts, such as sodium citrate. It’s easier for companies to list the sodium content than it is to calculate the pure salt (Na) content, since NaCl typically has a higher chloride to sodium ratio. Since it’s also easier to add salt (NaCl) to your diet, I’m basing my decisions on the use of this compound. Now, to say that the evidence varies in terms of the need for added salt in your nutrition is an understatement. The only reliable answer to the question “should I be supplementing my salt intake on longer runs?” is “it depends”. This is certainly not the most helpful of answers, but it drives home the need for experimentation prior to race day.
There has been a great deal of focus lately on eating a low-sodium diet as a way of combating high blood pressure. In reality, the research is pretty clear that unless you are among the 30% or so of Americans who already have high blood pressure, cutting back on the sodium isn’t going to have a significant impact on your health (assuming you aren’t grossly overdoing it, of course). None-the-less, pre-packaged foods love to add “low sodium” to the labels in the hopes of enticing health-conscious but relatively uninformed consumers. Since we started mass-producing food and moving away from locally grown sources, our average sodium intake has gone up substantially due to preservatives and additives for flavor. The recommended amount of sodium for the average adult is 2400 mg, which is much less than the 3400 mg average in the U.S.
Now, as a runner, I’m well aware that I lose salt through sweating while I am working out. In fact, this is the main reason that sodium supplements have proliferated on the market. The research is quite varied when it comes to the need for sodium replacement to prevent hyponatremia (low sodium concentration in the blood), with some studies indicating that sports drinks with varying levels of osmolality had no impact on absorption or the prevention of muscle cramps, whereas other studies have found a significant impact. Whether or not it has a positive impact on the absorption into the bloodstream, it seems safe to assume that moderate levels, based on sweat replacement, can’t hurt.
In order to calculate fluid loss during running, you need to accurately measure weight change and fluid consumption. Once you do that, you can plan accordingly for how much fluid you should be consuming, preferably at 20 to 30 minute intervals. This also tells you how much sodium you are sweating out, as sweat contains between 2.25 and 3.4 grams/liter, and the average runner will sweat out 1 liter of water per hour. I plan to couple this fluid consumption with my nutrition, based on needing around 250 calories per hour (this seems to vary between 200 and 300 based on height, weight, pace, etc.). Ideally, I’ll be getting a majority of my calories from carbohydrates until I’ve been running for 4-6 hours, after which point I can start adding in 25% protein to my nutrition. There is really no needed for added fat, since you body has enough to run on for days, but it’s unavoidable in most nutritional supplements. Ideally my nutritional choices will allow for the 500-700 mg of sodium per hour recommended by the American College of Sports Medicine.
There is no question that this is a complicated puzzle, and I feel as though every time I think I might have one piece figured out, the rest start moving again. This is the curse I must endure as a quintessential inputer!