Maltodextrin is a high GI source of carbohydrate. It is simply a string of glucose molecules. This string is easily digested and therefore the glucose molecules are quickly absorbed. Basically, MD acts jsut like glucose. Hence, the high GI and a rapid increase in BG.
1) I believe GI is measured by calculating blood glucose elevation (the area under the curve, over fasting baseline) relative to a reference, for two hours following administration of the food. Now if pure dextrose's curve (as GI=100) looks like a fat spike and a dive, any food that raises BG steadily and significantly without triggering a crash could achieve a high GI. Is it possible that MD falls into this category?
Our insulin is what causes the BG to "crash". As BG increases, insulin is produced to regulate the BG. Since MD acts like glucose, insulin will kick in to "crash" the BG back to normal.
2) Does the Dextrose Equivalence of the MD made a difference to absorbtion? If so, do we know what DE of MD was used to yield a GI result of 105? Does anyone know the DE of the MD they are using? (Relation question to anyone how happens to know: does our body have to split glucose down to one-molecule size before absorbing it into the bloodstream?)
In performing GI testing, the number of carbohydrate grams is kept equivalent (50 grams). So 50 grams of carbohydrate from dextrose was measured against 50 grams of carbohydrate from maltodextrin. Since they are both ~100% carbs, the test was probably performed on 50 grams of each of them.
Glucose is one-molecule in size. Any other polysaccharides (including MD) must be broken down into single units in order to be used by the body.
3) Many products that include MD as a main carb source effectively claim it is low-GI. Now I do not want to trigger a lot of "don't believe the hype" posts, but consider that if we didn't all see MD as 105 on the GI, "conventional" knowledge would say sure, MD has a low GI because the glucose polymers aren't broken down instantly, wouldn't it?
A food can have MD as its main carb source and still be considered low glyemic (does NOT mean it has a low GI), if the overall amount of carb is low. Drinks like Ultra Pure Protein have only 2-4 grams of carbs, all coming from MD. I have seen some powders that have 2-4 grams of carbs all from MD, too, and they are low glycemic. So even though the carb is high glycemic
, the glycemic load (which is the true measure of glycemic response) is low.
To calculate glycemic load, multiply glycemic index by number of carbs and then divide by 100. For foods that have multiple sources of carbs, you must know the amount of carbs from each source and then the glycemic loads can be summed to acheive the total.
If you are looking for good post-workout meals/shakes, include the powders with high carbs from MD. For pre-workouts, include low amounts of MD or just include lower glycemic carbs
. Every body is different and we all have different responses to different glycemic loads. If you are looking for a low glycemic meal replacement, I recommend Prolabs Lean Mass Matrix. Carb source is from brown rice, barley, and oat bran...mmmmm!! Hope this helps.