Gels
Quentin Grady Writes:
What I am wondering is what effect if any do the various gelling agents have on lowering the glycemic index.
Marty B. Responds:
There have been human studies on adding fiber to foods that produce a high glycemic index to see if the fiber will slow the absorption of glucose and therefore lower the glycemic index. Some work, others don't.
For fiber to work this way, it has to form a gel-like colloidal state in the small intestine.
For water-soluble fiber, there are two main properties, water-holding ability and viscosity. If the fiber increases viscosity, it can slow glucose absorption.
The fiber in carrots is a fiber that has good water holding ability but no viscosity. That's why carrots have such a high glycemic index. The fiber in beans has some water holding ability but it produces good viscosity, that's part of the reason why beans have such a low glycemic index.
I do not list carrots as a high glycemic index food to be avoided. I have used glycemic index plus carbohydrate content per 100 grams of the food to refine my advice on what are good foods and what are bad foods as far as glycemic index is concerned.
Both white (baking) potatoes and sweet potatoes (yams) have large amounts of starch with nearly identical properties (mostly amylose) along with decent amounts of water-soluble fiber. But the glycemic index for these two foods is very different. Using glucose as the standard, white potatoes have a glycemic index of 70 while sweet potatoes have a glycemic index of 51. The difference is that white potatoes have no fiber that can form a viscous gel-like state in the small intestine while sweet potatoes do.
Mixing beans with rice in a meal will lower the glycemic index of the rice (but the combined glycemic index of the bean/rice combination is still going to be higher than the beans alone).
Citracel is hydroxycellulose which has good water-holding capacity but no viscosity capability. Metamucil (psyllium) has even better water-holding ability compared to Citracel but it does not increase viscosity that much.
Gelatin is highly viscous when eaten but once it gets into our body, the viscosity is gone. Now if you mixed guar gum with the gelatin, you have a dynamite combination.
I cover all of the food additives in my course and some of them turn out to be highly beneficial to human health (contrary to popular opinion).
Gelatin and guar gum are both approved food additives that are used to stabilize and thicken food. Gelatin can not form a viscous mix in the human gut because it is partially degraded by human digestive enzymes (starts in the stomach). Guar gum on the other hand can only be handled by bacteria in the human gut so in the upper end of the small intestine where the food comes out of the stomach, you will have an extremely viscous mix that stays intact for a long way through the small intestine if there was a decent amount of guar gum in the food that you ate.
Health food stores sell guar gum but you have to be extremely careful if you decide to use it. You need plenty of water or you can end up with a mass that is so viscous that you will have trouble moving it through your small intestine (can cause intestinal obstruction).
Most of us use flour to thicken our sauces, if you substitue guar gum for the flour, you have done something really good to help control your blood glucose level.
This is the method that I prefer because you will add just enough guar gum to thicken the sauce. If you use the guar gum capsules, you are never sure if you drank enough water to prevent potential problems.
Guar gum can be added to any food that you are cooking. For stir-fry, just a little guar gum sets the juices up nicely at the end of the cooking so that you can get all of the juice which often gets left behind.
Guar gum is one fiber that has been extensively studied in humans and it has been proven to significantly reduce the absorption of glucose from any food that it is mixed with. But it also slows mineral absorption, vitamin absorption and essential amino acids absorption.
The key word here is "slows", I did not say stops. As the food with guar gum makes it's way along the small intestine it will eventially come in contact with bacteria that will start to break it down and decrease the viscosity which will then result in a normal rate of absorption for the essential nutrients in food.
However, if you have absolutely no bacteria in your small intestine, guar gum could cause some problems. For the typical American with just 12 grams of fiber in the diet, most of the bacteria are in the colon.
Metamucil and guar gum where chosen as fiber supplements for humans because they produce less gas than some other kinds of fiber would. Metamucil and guar gum can both produce gas but they are not digested by bacteria as well as other kinds of fiber. If you have seen the adds for Citracel you know that gas production by metamucil is used as a selling point for Citracel which can not be metabolized by human gut bacteria at all.
What I tell my students is that if they want to add guar gum to their diet, change their diet first to get the RDA for fiber and then start to use the guar gum.
Marty B, "You are what you eat."
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