Waxy maize and dextrose/maltodextrin are popular ingredients to throw into a post exercise concoction. The hope is that after consumption, an insulin spike is provided, shunting nutrients to muscles to aid in repair, recovery, and growth.
Dextrose (glucose) is a simple sugar found mostly in fruits. It is a major source of energy in the body. When ingested or produced by the breakdown of disaccharides and polysaccharides, glucose is absorbed into the blood from the intestines by a facilitated transport mechanism using carrier proteins. Excess glucose in circulation is polymerized and stored in the liver and muscles as glycogen, which is depolymerized to glucose and liberated as needed. Dextrose has many uses. It is recommended to diabetics for consumption when they have low blood sugar. It is used as a sweetener for food products. It is also currently used to spike insulin for post exercise purposes.
Currently, waxy maize is advertised to be used for pre and post workout carbohydrates. Here are some of the advertised claims:
“Waxy Maize Starch compared to dextrose or maltodextrin has a higher molecular weight.
Waxy Maize Starch compared to dextrose or maltodextrin bypasses the stomach, is absorbed by the intestines and immediately is assimilated at a much faster rate, reportedly almost double the rate.
Waxy Maize Starch can assist in the absorption of supplements (creatine…etc) as it helps bypass the stomach and allow the body to assimilate them at a higher rate.
Waxy Maize Starch compared to Dextrose/maltodextrin has the ability to refuel glycogen stores much faster. Again this is accomplished through the bypassing of the stomach and go straight to the intestines for absorption. Through this is where the immediate pump in your muscles can be observed.
Compared to dextrose and maltodextrin, waxy maize starch won’t cause the bloating and water retention.
Waxy maize is considered a long chain complex carbohydrate making it sugar free.”
The molecular weight (MW) of dextrose (anhydrous) is 180.16. The MW of waxy maize and maltodextrin both vary. Maltodextrin is a short chain of dextrose molecules linked together, making its molecular weight greater than dextrose. Chain sizes vary, leaving molecular weight varied. However, the chain sizes of maltodextrin are significantly smaller than those of amylopectin. Maltodextrin is known to reach approximately 20 glucose units. Waxy maize starch is composed of amylose and amylopectin. Amylose consists of a straight chain of glucose molecules bound to their neighbors by oxygen links. The bulk of the product is amylopectin, which has a branch chain linked in after every 25 molecules of glucose on the main chain.2 Chains of amylopectin vary in size leaving molecular weight difficult to determine. Amylose molecules consist typically of 200 to 20,000 glucose units.
Amylopectin differs from amylose in being highly branched. Short side chains of about 30 glucose units are attached approximately every twenty to thirty glucose units along the chain. Amylopectin molecules may contain up to two million glucose units. This makes its molecular weight inconsistent yet very large.
As much as I have researched, there have been no studies on waxy maize bypassing the stomach and being absorbed at “double the rate” of dextrose/maltodextrin. In fact, there are very few studies on waxy maize at all. The most relevant study I found involved the comparison of waxy maize, maltodextrin and white bread. And I have read nothing that contradicts any of the information.
According to this graph, the quickest thing to be absorbed into the blood stream was the maltodextrin. This resulted in elevated blood glucose levels. In order to “refuel” glycogen to the muscles, glucose must be delivered to the blood stream. It is then delivered to the liver and muscles where it is converted and stored as glycogen. The fastest way to refuel muscle glycogen is to spike blood glucose levels as fast as possible.
Not only did the experiment yield that maltodextrin provided a larger insulin spike, but it was absorbed into the blood stream faster than waxy maize was. According to Graph 1, the control group (50g of white bread) provided a larger insulin spike than waxy maize did.
The release of insulin is very important. Insulin causes cells in fat, muscle and liver to take in glucose and store it. Without insulin, glucose cannot be delivered to the cells. Insulin is produce
d in the pancreas and is released when protein is ingested and when glucose is detected in the blood. Insulin increases DNA replication an
d protein synthesis via control of amino acid uptake. When insulin levels are high, the body’s ability to transport nutrients elevates.
|Calculated glucose control||White bread control||Maltodextrin||Waxy maize|
|Glycemic index (2-h)||100 ± 0a (100)||71 ± 0a (71)||163 ± 37a (106)||63 ± 11b (58)|
|Glycemic index (4-h)||100 ± 0a (100)||71 ± 0a (71)||127 ± 27a (89)||60 ± 11b (64)|
According to Table 1, maltodextrin, when compared to dextrose, yields a larger insulin spike. However, because dextrose is a simple sugar, it does not need to be broken down any farther. It hits the blood stream faster, providing a faster spike.
The glycemic index ranks carbohydrates according to their effect on blood glucose levels. Maltodextrin has a glycemic index of 163, glucose 100, white bread 71 and waxy maize 63.1
There are several reasons for the glycemic index of waxy maize to be so low. The body’s salivary amylase can only break down so much. Waxy maize must enter the intestines where pancreatic amylase can break down the remainder into maltose (disaccharide), maltriose (trisaccharide), and a group of alpha-limit dextrins (shorter chains of amylopectin) which contain branch points from amylopectin. Then, maltose and maltriose are broken down by hydrolysis into molecules of glucose. Then, alpha-limit dextrins (amylopectin) go through the process again to be broken down.
Amylopectin and amylose are both complex molecules of carbohydrates. Amylose is easier to break down because it’s a linear chain. Amylopectin however, is highly branched. The more branches amylopectin has, the more time it takes to break down. This reflects its lower glycemic index and high molecular weight.
There are several reasons for the glycemic index of dextrose and maltodextrin to be so high. Once a carbohydrate is ingested, it must be absorbed through the intestines. The majority of glucose is absorbed in the duodenum. Unless you are absorbing pure glucose, the only way to get glucose from carbohydrates is to break it down. Maltodextrin begins to break down in the mouth, as the salivary amylase has little problem breaking the weak hydrogen bonds.
Majority of maltodextrin is in powder form. This is then added to water, and unless mastication occurs, very little, if any digestion occurs in the mouth. Salivary amylase is then neutralized in the stomach. This leaves digestion to wait until maltodextrin hits the small intestine. This digestion delays absorption, making the insulin spike set in quicker with dextrose. Dextrose is absorbed faster than maltodextrin. It does not need to break any hydrogen bonds. Once in the small intestine, no enzymes need to be released, it’s ready for absorption.
For post exercise consumption dextrose/maltodextrin is more beneficial than waxy maize. This is because of the insulin spike it creates, therefore increasing the rate of absorption. Thus far, the only claims stated about waxy maize that have been proven are: it has a higher molecular weight and it is considered a long chain complex (redundant) carbohydrate, making it sugar free. Studies prove that the greater the molecular weight of the carbohydrate, the more chains of glucose it contains and the harder and longer it takes to break down, delaying absorption.
A prolonged insulin spike leads to an increase in fat storage. Waxy maize is easy on the stomach and in some instances better to sip on throughout the workout, compared to Gatorade. Using waxy maize as a semi-slow digesting source of carbohydrates is safe. It’s better than eating white bread for a carbohydrate meal replacement.
If you’re looking for a carbohydrate replacement with a fairly low glycemic index, waxy maize is not a horrible choice. Adding it to protein for a meal replacement is more beneficial than the majority of the meal replacements on the market that contain maltodextrin as their “complex” carbohydrates. (Do not be fooled by advertising. Though maltodextrin is complex by definition, it does not deliver desired effects.) However, simple sugar is preferred over complex carbohydrates for post workout consumption, based on facts.
1. Sands A.L., Leidy H.J., Hamaker B.R., Maguire P, Campbell W.W. Consumption of the slow-digesting waxy maize starch leads to blunted plasma glucose and insulin response but does not influence energy expenditure or appetite in humans
Nutrition Research. 2009; 29(6):383-390
2. Human digestive system. (2009). In Encyclopedia Britannica. Retrieved November 12, 2009, from Encyclopedia Britannica Online: http://www.britannica.com/EBchecked/topic/1081754/human-digestive-system
3. Database pages created by A/Prof Gareth Denyer and Scott Dickinson using data collected by Professor Jennie Brand-Miller & SUGIRS Last Modified: February 9, 2005 Retrieved from: http://www.glycemicindex.com/