All carbohydrates are sugar. It doesn’t matter if it is classified a “sugar” or a “starch” or even “fiber,” all types of carbohydrate are formed from 3 simple sugars – glucose, fructose, and galactose. When the carbohydrate is just one or two sugar molecules, it is classified as sugar. When the carbohydrate is 3-10 sugar molecules, it is classified as an oligosaccharide (oligo-, representing the 3-10 length, and -saccharide, meaning sugar). Finally, when the carbohydrate is longer than 10 sugar molecules, it is classified as a polysaccharide (poly-, meaning many), otherwise referred to as “starch.” Since we are only dealing with, essentially, 3 different molecules, how do we have so many different types of carbs?
Well, we can have different sequences of sugars, which means a glucose could be linked up with another glucose then another glucose in a linear chain, or glucose could be linked up with a fructose then a galactose. These would both be 3 sugar molecules, but they would be fundamentally different in their biological effects including absorption, osmotic load, and glycemia. While different sequences are possible, most starches are composed of glucose. Maltodextrin, for example, is all glucose (and also found on supplement labels as “glucose polymers”), mostly linked together in straight lines. This introduces another concept – branching.
Branching is kind of like sequencing, but because we are almost always dealing with glucose, branching is a better “difference maker.” Notice how we keep saying “linear” and “chains” of glucose and other sugar molecules? Carbohydrates are mostly straight in their structure with one sugar molecule following another sugar molecule following yet another sugar molecule etcetera. Under normal conditions, every once in a while the carbohydrate chain will “branch.” This means it takes off in two directions instead of continuing in one straight line. Usually, the branch is not very long and when cleaved from the main chain, it would be an oligosaccharide by itself. Different branching patterns and lengths makes different sources of carbohydrate unique. Branching carries an especially important function for endurance athletes and other athletes replacing carbohydrates, particularly during exercise.
Branching increases carbohydrate digestibility. Have you ever had a sugar-based drink during exercise and it just sits in your stomach, feeling heavy? Sugars (as simple sugars and labeled as sugar on the nutrition facts – not to be confused with all carbohydrates) have low molecular weight and high osmolality. Osmolality basically means how much water the carb will suck into the intestines during absorption. Starches have high molecular weight and low osmolality. They do not pull as much fluid into the gut, but they are digested more slowly, which is why they are recommended as healthier carbs – because they have a slower release of glucose into the blood.
For the endurance athlete, there are pros and cons to both sides. Simple sugars can rapidly increase blood glucose, which gets more fuel to active muscles more quickly, but they can cause gastric distress. Starches do not create much, if any, osmotic GI stress, but they are more difficult to digest. Starches with little branching also tend to sit in the stomach longer before moving on into the intestines. In the scientific literature, this is referred to as “gastric emptying time.” Although the stomach usually gets the credit, it is actually in the intestines where carbohydrates are absorbed into the blood stream, so until the carbohydrate passes the stomach, blood glucose will not be increased and muscles will remain “hungry.” Carbohydrates with more abundant branching have a faster gastric emptying time. If you’ve ever had a carbohydrate such as cyclic cluster dextrin (CCD – also known as highly branched cyclic dextrin [HBCD]), Ucan, or vitargo, you may notice that you almost feel hungry ~30 minutes afterwards. This is because the stomach has mostly emptied its contents and you can actually sense the emptiness. I, for one, love this effect because having to eat near exercise always feels like a burden to me. Having a fast gastric emptying time doesn’t only increase absorption and decrease potential for GI stress, it improves performance to a greater extent than starches like maltodextrin and sugars like glucose.
Now that we know about sequencing, branching, gastric emptying time and a bunch of other interesting aspects of carbohydrates and their metabolism, let’s talk about what is likely the best carbohydrate for athletes – cluster dextrin, aka cyclic cluster dextrin, aka highly branched cyclic dextrin, aka the spicy chicky choop choop. Okay, not that last one – I’ve officially seen too many Taco Bell commercials, but we know cluster dextrin is a hot customer just because it has so many aliases!
When compared head-to-head with maltodextrin, simple sugars, and other sources of carbs, cluster dextrin has a much faster gastric emptying time. This has been documented to reduce athletes’ sensations of GI stress. Better yet, cluster dextrin increases total glucose absorption from the gut. It is slower to peak than pure sugar, yet slightly faster than other starches, but because of its highly branched structure, it is very easily metabolized and absorbed. When cluster dextrin is consumed before or during exercise, its superiority for increasing total glucose absorption enhances the fuel supply to active muscles, which improves their ability to continue performing at high work rates.
In cyclists, cluster dextrin reduced athletes’ perceived exertion to a fixed amount of work over a 2 hour span. The athletes consumed the highly branched cyclic dextrin or maltodextrin after the first hour of exercise and felt the exercise become easier with just 15 grams of highly branched cyclic dextrin. In swimmers, cluster dextrin was compared to glucose at a dose of 1.5 grams per kg body weight consumed 20 minutes before exercise. Each swimmer completed 10 sets of 5 minutes at 75% VO2Max separated by 3 minutes rest followed by a swim to exhaustion test at 90% VO2Max. Blood glucose values collected between each set showed that cluster dextrin maintained higher blood glucose values during exercise, and the time to exhaustion was enhanced nearly 2-fold when athletes drank the cluster dextrin beverage.
Superman has the Justice League; LeBron James can’t win it all without Kyrie Irving or Dwayne Wade; and Wolverine had the X-Men … well, he kind of tried to run his own show, but (spoiler) he’s dead now – at least as far as the movies are concerned. The point here is, although there is an undeniable greatness about Superman, LeBron, and Wolverine (and cluster dextrin, of course), they don’t do it alone. If you want to be performing at your absolute best, just one source of carbohydrate isn’t the answer – not as cluster dextrin, not as maltodextrin, not as glucose or fructose or honey or bread. To be the best, it is pride you must shed. Check your ego at the door. Keep confidence in your head. Multiple carb sources are from what champs are bred!
They said I could be a doctor of philosophy, but they didn’t say I couldn’t be a Dr. Seuss!
Having more than one carb source is important for athletes competing in sports with high energy demands. The highest energy demands are found in the endurance sports. To run, bike, or swim at the greatest speed possible for extended periods of time requires a ton of calories (in case that is news). Most of these calories come from carbohydrate. Unfortunately, the body can only store a limited amount of calories as carbs as liver and muscle glycogen. Hence, we must refuel, and to maintain performance, we must refuel pretty large quantities in relatively narrow windows of time.
Glucose can only be absorbed from the gut at a rate of about 1 gram per minute. Adding a mixture of glucose and starch enhances absorption rate by a small margin, but adding fructose to glucose and/or glucose-based starch nearly doubles the rate of carbohydrate absorption. More on the topic of multiple carbohydrate fueling can be found in our article, Race Fueling for Endurance Athletes.
Yes, and we believe it to be cluster dextrin. No carb is best for performance when ingested alone, but if there were to be a single source, our money is on cluster dextrin. It is faster than other starches but doesn’t carry with it the risk of GI stress, and its easy digestion makes it easier for the athlete to keep on fueling through an entire race. For these reasons, cluster dextrin has been included in our landmark sports drink, SustainElite. Unlike most supplements, which are pieced together with a first priority of fitting a budget then seeing what science is available to support it, EndurElite is born from science. We start with the research and formulate based on what it tells us will work best. The results are the best supplements for endurance athletes on the planet. When it comes to a sports drink, we want NO gastric distress and high nutrient availability, and that is exactly what is provided by cluster dextrin. Combined with a quantity of fructose equal to 20% of total carbohydrates, maximal absorption is enabled, and the athlete can experience maximal performance.