Re: Does the addition of sugar speed up the rate of water absorbtion in the gut

Aloha, Richard,
     I just re-activated my madsci listing from being off during the 
summer;  sorry about the lag-time in answering your most interesting 
questions.
     Regarding the questions of sugar speeding up the rate of water 
absorption in the gut and the mechanism:  Yes, there is ample evidence that 
that is so...and it is part of the reason that ORT works so well, 
regardless of what your friend might believe.  It works because glucose and 
sodium (from the table salt in the solutions) co-transport at the cells 
which line the small intestine.  As the sodium is transported, it 'drags' 
water with it.  Thus, the glucose, sodium and water are all absorbed into 
the capillaries that drain the gastrointestinal tract.
     There is an excellent, easily understandable, chapter about ORT in the 
latest (4th) edition of _Pediatric Nutrition Handbook_, published by the 
American Academy of Pediatrics (1998)...if you're interested in pursuing 
this further.
     Regarding the question about using 'sports drinks,' such as Gatorade; 
These drinks are what nutritionists call 'functional foods.'  You are using 
water with a bit of carbohydrate (glucose, etc.) and salt.  An expensive, 
but convenient, way to get those nutrients.  Water, by itself, is usually 
just fine for moderate exercise.  The only time that these drinks do much 
good (and are really needed) is in endurance events, such as events lasting 
more than 2 hours...or when there is really excessive sweating (like in the 
Honolulu Marathon, sometimes).  I am not a sports nutritionist, however.  
If you'd like to contact one, I could provide his e-mail address (with his 
permission, of course)...one of my colleagues that I co-teach the 
introductory nutrition course with, here at the University of Hawai`i at 
Manoa.
     I hope that this answers your questions.  Thanks for using the 
MadScientists Network.

Dian Dooley, Ph.D.
Associate Professor/Food Science and Human Nutrition 
,