Glycerol Hyperhydration?

An interesting discussion on glycerol hyperhydration. Does it work?

-->http://www.ultrunr.com/glycerin.html

An excerpt;

I have read the postings on the glycerol issue with interest, and need to inform you of several facts.
I am one of the University of New Mexico scientists who first researched glycerol hyper hydration for improved exercise performance. Based on our and Bud Riedesel's findings (1987), the university invested in patent protection for using glycerol as a hyper hydration agent suitable for use during exercise. In 1996, the patent was purchased by InterNutria, a nutritional supplements company within the larger InterNueron Pharmaceutical Company. Thus, InterNutria has patent protection for using glycerol hyper hydration for enhancing exercise performance.
I am currently contracted by InterNutria to provide scientific advice and commentary on their glycerol product - "ProHydrator". ProHydrator was scheduled to be released to market this June, but the USOC ban on glycerol 'came out of the blue' and has delayed the product release. Such a delay was decided by the company due to the sponsorship of USA Triathlon, as well as several professional triathletes.
From my understanding, the USOC ban is based on glycerol being classified as a tissue dehydrator. Other tissue dehydrators are mannitol, sorbitol, and urea. Such substances are routinely used in clinical practice to dehydrate the brain and eye as a treatment for edemas resulting from a variety of clinical disorders. It just so happens that mannitol, sorbitol, and urea are also potent osmotic diuretics. Glycerol seems to have been included in the banned list of mannitol and sorbitol due to the potential for glycerol-induced diuresis.
I have recently written a major review of the clinical and applied uses of glycerol ingestion. It is currently in review. Within this manuscript is a section that pertains to glycerol-induced diuresis. It is important to remember that glycerol ingestion is not the same as glycerol hyper hydration. The latter involves the additional ingestion of 1-2 L of water. Simply ingesting a concentrated solution of glycerol will not hyper hydrate the body, but dramatically increase glycerol concentrations in the blood, interstitial fluid, and kidney filtrate. Increased urinary glycerol has the potential to increase urine flow due to retarding water reabsorption in the kidney. This is the mechanism of the diuresis from mannitol and sorbitol.
Glycerol does not cause a marked diuresis, however, because glycerol is still rapidly reabsorbed in the proximal and distal tubules. Mannitol and sorbitol are not. There is no evidence in the medical literature for a glycerol-induced diuresis. Nevertheless, anecdotal expressions of glycerol-induced diuresis occur in many manuscripts.
I have written a scientific reply to InterNutria for use in the company petitioning the USOC to remove the ban on glycerol.
It is ironic that glycerol has been used by the world's elite athletes for many years. Although it is easy to assay for urinary glycerol, and interpret data, I do not think the testing lab has or is currently performing the assay. It would be easy to detect exaggerated use of glycerol as the kidney can reabsorb almost all glycerol up to blood glycerol concentrations approximating 1.2 mmol/L. As resting blood glycerol approximates 0.05 mmol/L and may increase to 0.5 mmol/L during extreme prolonged exercise and carbohydrate depletion, the only way to cause glycerol to appear in the urine is to ingest large quantities. Thus, if the USOC wanted to, they could easily determine a urinary concentration indicating large amounts of glycerol ingestion. For your information, urinary glycerol can increase to above 20 mmol/L within 30 min after ingesting 1.2 g glycerol/kg body wt.
The USOC is not justified in the ban on glycerol for hyper hydration or proposed metabolic advantages to athletes. Hyper hydration is no worse than ingesting liquid carbohydrate or water during exercise. In addition, glycerol turnover data indicate that 60% of glycerol is converted to glucose in the liver and kidney, 30% is incorporated into glycolysis for oxidation, and the remainder is presumably involved in triacylglycerol metabolism.
It appears that the ban on glycerol is a mistake and should be reversed in the near future. Failure to reverse the ban will not only expose to elite athletes to continued high risks of heat injury, but potentially result in a series of law suits from athletes and nutritional companies against the USOC.
I hope these facts help you understand the glycerol saga !
Rob Robergs, Ph.D. Director: The Center For Exercise and Applied Human Physiology The University of New Mexico