Sunday, March 1, 2009

On Gatorade


Did you know that the inventor of the popular sports drink "Gatorade" was a Nephrologist? The 2007 NY Times obituary of J. Robert Cade, the University of Florida nephrologist who concocted Gatorade, describes the story of the beginning of the now billion-dollar sports drink industry. Ironically, Dr. Cade passed away at the age of 80 of kidney failure.

As the story goes, football coaches of the Florida Gators football team were perplexed by the fact that their players were unable to urinate after football practices in the humid Florida swampy summers. Enter J. Robert Cade, who noted that this was a simple response to hypovolemia, and intended to correct the situation by having the players drink a solution of sodium, potassium, glucose and sucrose. The initial versions were substantially more salty than current versions, and as legend has it, it was not until Cade's wife came up with the idea of adding lemon to the stuff (and also, probably reducing the salt concentration) that it started to catch on. Also interesting, Cade initially offered the University of Florida the opportunity to purchase the patent rights--they initially declined, and once the sales of Gatorade began increasing, they sued Cade and there was a protracted legal battle for the rights to the sports drink.

In its current form, according to the Gatorade FAQ web page, Gatorade is stated as being slightly hyperosmolar compared to blood. However most of the osmolarity here is being provided by sugar, and once it is metabolized, it is in fact in essence a hypoosmolar solution, as Gatorade falls into FDA's category of "low-sodium" products. This is why ingestion of large quantities of Gatorade during a marathon, for instance, may be associated with the development of dangerous hyponatremia.

Oral rehydration solution--which has been attributed in decreasing worldwide death rates from diarrhea in developing countries by millions--has a much higher sodium content, 75 mmol/L according to WHO Guidelines. In contrast, Gatorade & other sports drinks have a typical NaCl concentration of between 10-25 mmol/L. In addition, the concentration of KCl is much lower in sports drinks (3-5 mmol/L) compared to that of oral rehydration solution (20 mmol/L) by WHO guidelines.

This study was a randomized controlled trial looking at the treatment of adult patients with viral gastroenteritis in the U.S. with either Gatorade, Pedialyte, or oral rehydration solution. Patients in all three groups showed similar rates of recovery, indicating that all three options are probably safe. However, the Gatorade group showed higher degrees of hypokalemia.

Here is the full composition of oral rehydration solution according to WHO, as taken from wikipedia:
Ingredient g/L Molecule mmol/L
Sodium chloride (NaCl) 2.6 Sodium 75
Glucose, anhydrous (C6H12O6) 13.5 Glucose 75
potassium chloride (KCl) 1.5 Potassium 20


Chloride 65
trisodium citrate, dihydrate Na3C6H5O7•2H2O 2.9 Citrate 10

1 comment:

Joel Topf said...

Sweet post. I love the mixture of history, minutia and clinical relevance.

It'll be required reading on day one of the consult service tomorrow.