MadSci Network: Biochemistry

Re: How does sugar effect physical and academic skills.

Date: Mon Sep 8 18:01:09 2003
Posted By: Dian Dooley, , Associate Professor, Food Science and Human Nutrition, University of Hawaii at Manoa
Area of science: Biochemistry
ID: 1062010917.Bc


      Let me begin with a bit of basic nutrition.  'Sugar' is a term for 
simple carbohydrate;  the most common type of sugar in our food supply is 
probably sucrose (cane or beet sugar)...and it is 'pure' carbohydrate, 
since it has been extracted and purified from one of those two plants.  
All carbohydrates that can be absorbed by the human digestive tract 
(sugars and starches) are handled the same way, once in the body.  The 
simple sugars that result from starch digestion are handled just the same 
as the simple sugars directly absorbed, as is.

     The main difference between how the body absorbs sugars from starches 
or sugars, as they occur in nature or as they are added to processed 
foods, is in the speed at which they are absorbed through the small 
intestine into the blood stream.  The simple sugars (glucose, fructose, 
galactose)...sucrose is simply a chemical combination of glucose and 
fructose)...are absorbed more quickly than those from starch, since the 
starch molecules must first be broken down in the digestive tract into the 
simple sugars, before they can be absorbed.

     Now, to your question...'sugar,' especially when eaten as part of a 
food, even a processed food, like a candy bar, would have little effect on 
your ability to function (either physically or mentally), because any 
effect would be blunted by the other nutrients (especially fat and 
protein) which would be part of the food.  Eating straight sugar might 
have a small effect on your blood sugar (glucose) concentration, but your 
body, when everything is working correctly, has very effective feedback 
biochemical mechanisms (controlled mainly by the hormones insulin and 
glucagon) to restore your blood glucose to a safe/normal range.  The 
tissues in your body rely on a certain range of glucose in the blood 
stream to function properly, so the body will protect the blood glucose 
level...this is what goes wrong when a person has diabetes...the control 
mechanisms just don't work right...and the blood glucose gets way too 
high, for too long...and permanent damage can occur.

     I've actually done research in this field...looking at the effect of 
high doses of sugar (sucrose) on behavior in juvenile delinquent males.  
The interesting thing that we found was that in a subset of these 
guys...the ones who had major problems with attention...sugar seemed to 
calm them down and allowed them to complete some of the behavioral tasks 
better...exactly what the biochemistry would predict...probably something 
related to increasing serotonin levels in the brain (which we did not 
measure directly).

     If you were severly deficient in energy, then maybe a dose of sugar 
would help you 'recup'...but, so would eating food...either containing 
sugar or not.  So, I guess my answer is that long-term, sugar would have 
little effect on either academics or physical skills.  Eating FOOD, 
however, has been shown to have a large effect on learning...skipping 
breakfast is not a good thing...this has been shown in a number of 
studies.  Likewise, semi-starving (like on a reducing diet or during 
eating disorders) effects the brain because of lack of adequate calories, 
and learning and physical functioning can be severly affected.  Kind of 
like trying to start a car with little/no gas in the tank (after an 
overnight 'fast').

     I hope this helps answer your questions.


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