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HIV NUTRITION UPDATE
VOLUME 8, ISSUE 5
 

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Questions & Answers On Sugar

The question and answer below highlights the Virtual Faculty at Jennifer Jensen's Nutrition Power web site (sugar questions).

 
"Readings of blood sugar would be up and down within the 2-hour mark too."

 
 
 
 
 
 
 
 
 
 

Question #1: Sugar Metabolism
I am doing a research project on sugar metabolism, and I was wondering, after you eat something, say a bowl of cereal, on an average, how long does it take for your sugar (as in blood sugar) to metabolize and affect the blood sugar? (Time as in hours.) (January, 2002)

Answer: Charlie Smigelski, RD, responds: Stomach emptying from a bowl of cereal would depend on cereal type, fiber content, and total volume of milk combined with the cereal. In general, though, within an hour or two the stomach would be emptied of the average bowl of Rice Krispies or Cheerios, the rice quicker than the whole grain oats. Full-fat milk would also be slower than skim milk. Readings of blood sugar would be up and down within the 2-hour mark too. 

Question #2: Sugar Metabolism
Comments on the metabolism of fructose versus glucose or sucrose? Is there a difference? And, if so, what does it mean? (July, 1998)

Answer: Chester Myers, PhD, responds: This is a complicated area, and the answers you want may not even be known. I would like to have my biochemistry text in front of me (which I don't), but for now, here are a few comments. Even so, this may be a bit lengthy.

 

 

 

 Fructose and glucose are both simple sugars, also called monosaccharides. Glucose also is known by the name dextrose - that's the name we often see on those plastic bags of clear liquid beside hospital beds, with a tube dripping into the vein of a patient. Glucose is the sugar in corn syrup, and is produced by the breakdown of starch, a polymer made up of glucose molecules joined together. Fructose has the same atoms as in glucose (carbon, oxygen, and hydrogen), but when joined together we get sort of the mirror image of glucose - so think of glucose and fructose as left-handed and right-handed versions. Honey contains both glucose and fructose.

Sucrose is a disaccharide meaning there are two simple sugars joined together. It is the sugar found especially in sugar cane, sugar beet, and maple syrup. For sucrose, the two sugars are glucose and fructose.

In the body, the glucose and fructose are absorbed as they are, although the absorption mechanisms differ. Sucrose, on the other hand, is broken down to the fructose and glucose by an enzyme of the small intestine. [Lactose and maltose are two other disaccharides, and the enzymes that break these and sucrose down are called, as a group, disaccharidases, and more specifically lactase, maltase and sucrase, respectively. You may already be aware of lactase since it has often been found "wanting" in HIV/AIDS resulting in gut cramps and/or diarrhea from dairy products.]

 
Once absorbed into the body, it is glucose that has special importance for the body. It is the central "fire wood" for our energy. Our body has a wonderful mechanism to make sure it gets an adequate, BUT CAREFULLY CONTROLLED, supply of glucose. Enzymes that break down starch to glucose are even in our saliva - since many of our foods are rich in starch, this seems to be one way Nature makes sure the starch digestion gets "on its way" early in the digestive process. If we don't have enough carbohydrate (carbohydrates include simple sugars and complex polymers such as starch that are sugars joined together), then our body has a complex system of chemical reactions that make it possible for glucose to be made from some parts of the protein in our food, or from some of the fat. There is also a series of reactions that enable fructose to supply some energy. This gets complicated, and I would want my biochemistry text in front of me to go further on this. The bottom line here, the control, is that the body uses other signals to try to maintain a fairly constant level of glucose in the blood stream. Insulin is a hormone that participates in this regulation. When our body stops making enough insulin we have Insulin Dependent Diabetes Mellitus (IDDM). When our body doesn't use the insulin properly (insulin insensitivity) there may be higher than normal levels of it, and then we have what is called Non-Insulin Dependent Diabetes Mellitus (NIDDM).
 
 
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4/1/2004