|MadSci Network: Biochemistry|
Aloha, 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.
Try the links in the MadSci Library for more information on Biochemistry.