The best carb source for cycling, running, and triathlon.

As we learned in the first CCD blog, CCD stands for Cyclic Cluster Dextrin and is actually a common term for the trademark name (CCD®) of Highly-Branched Cluster Dextrins (HBCDs). CCDs are made from corn starch by fermentation and molecularly resemble small pieces of glycogen, something your body knows how to assimilate into glucose.

CCD is found in First Endurance’s EFS-PRO, our Electrolyte Fuel System for use before, during, and after intense endurance exercise. EFS-PRO provides more carbohydrates and electrolytes per serving than EFS, and has the dipeptide L-Alanyl-L-glutamine (Sustamine®) that aids exercise performance during hydration (Hoffman et al., 2012; McCormack et al., 2015; Pruna et al., 2016). It also includes CCD as the predominant form of carbs, which may be its most significant upgrade compared to the standard EFS formula. Here’s why.

CCD is Simply Better

Advantages of Cyclic Cluster Dextrin over other carb sources include more rapid stomach emptying at rest (Takii et al., 2005), more rapid stomach emptying during 30-minute cycle ergometry (Takii et al., 2004), more rapid digestion to individual glucose molecules in exercising rats (Takii et al., 1999), and less GI disturbances and more comfort during cycle ergometry (Takii et al., 2004). In fact, belching was doubled when subjects consumed glucose and maltodextrin compared to water or CCD (Takii et al., 2004).

Blood glucose levels during cycle ergometry were maintained equally well by glucose, maltodextrin, and CCD , and always better than water alone (Takii et al., 2004). These results meant that CCD was better tolerated, delivered glucose to muscle as well as anything else, and had less GI discomfort (burping, flatulence). All desirable traits – but how was performance?

The first indication of enhanced exercise performance from Cyclic Cluster Dextrin in humans was from the exercise tolerance test, when perceived exertion during cycle ergometry for a fixed time was lower (but data was not shown) (Takii et al., 2004). Before that, animal exercise (swimming rats) was improved by CCD over other simulated sports drinks (Takii et al., 1999). Japanese men cycled for two hours and were given CCD or maltodextrin at one hour (Furuyashiki et al., 2014). Changes in Ratings of Perceived Exertion (RPE) were lower in the CCD group, although measures of blood energy metabolites were not different. This means that the brain may have had access to more glucose, perhaps lowering central fatigue, a known hindrance to performance.

“The ingestion of HBCD resulted in a significant increase in the time to exhaustion.”

[Shiraki et al., 2015]

When Cyclic Cluster Dextrin was ingested just before a strenuous bout of intermittent swimming lasting more than 80 minutes, a 70% longer time to exhaustion in the 90% VO2max end phase was seen compared to control or glucose feedings (Shiraki et al., 2015). Swim time to exhaustion was ~500 seconds for CCD vs. 300 seconds for water and glucose.

Elite swimmers were the subjects in a randomized, double-blind, placebo-controlled, crossover trial, making these results relevant to endurance sports. The dose was rather high (1.5 g CHO/kg), but is consistent with repeated dosing of CCD-containing sports drinks over the same time period in exercise lasting over 80 minutes. Plasma glucose and lactate were elevated by CCD more than the control and glucose groups at the end of the trial. Again, the results pointed to CCD having different effects than equicaloric amounts of glucose for extending endurance exercise performance.


Cyclic Cluster Dextrin is turning out to be a premier form of carbohydrates for extending exercise performance, largely because it doesn’t have the gut-busting drawbacks of other carbohydrate sources while delivering just as much fuel. CCD’s unique molecular structure gives it the ability to not have gastric side effects that other carbohydrates have, and it helps prevent central fatigue, which other carb sources simply cannot do as well. CCD is a better mousetrap for delivering carbs during endurance exercise.


Furuyashiki T, Tanimoto H, Yokoyama Y, Kitaura Y, Kuriki T, Shimomura Y. Effects of ingesting highly branched cyclic dextrin during endurance exercise on rating of perceived exertion and blood components associated with energy metabolism. Biosci Biotechnol Biochem. 2014;78(12):2117-9.

Hoffman JR, Williams DR, Emerson NS, Hoffman MW, Wells AJ, McVeigh DM, McCormack W, Mangine GT, Gonzalez AM, Fragala MS. L-alanyl-L-glutamine ingestion maintains performance during a competitive basketball game. J Int Soc Sports Nutr. 2012 Mar7;9(1):4.

McCormack WP, Hoffman JR, Pruna GJ, Jajtner AR, Townsend JR, Stout JR, Fragala MS, Fujuda DH. Effects of l-alanyl-l-glutamine ingestion on one-hour run performance. J Am Coll Nutr. 2015;34(6):488-96.

Pruna GJ, Hoffman JR, McCormack WP, Jajtner AR, Townsend JR, Bohner JD, La Monica MB, Wells AJ, Stout JRR, Fragala MS, Fukuda DH. Effect of acute L-alanyl-L-glutamine and electrolyte ingestion on cognitive function and reaction time following endurance exercise. Eur J Sports Sci. 2016;16(1):72-9.

Takii H, Ishihara K, Kometani T, Okada S, Fushiki T. Enhancement of swimming endurance in mice by highly branched cyclic dextrin. Biosci Biotechnol Biochem. 1999 Dec;63(12):2045-52.

Takii H, Takii Nagao Y, Kometani T, Nishimura T, Nakae T, Kriki T, Fushiki T. Fluids containing a highly branched cyclic dextrin influence the gastric emptying rate. Int J Sport Med. 2005 May;26(4):314-9.

Takii H, Takahashi K, Nishimura T, Kuriki T, Fushiki T. A sports drink based on highly branched cyclic dextrin generates few gastrointestinal disorders in untrained men during bicycle exercise. Food Sci Technol Res. 2004;10(4):428-31.

June 15, 2023 — Luke Bucci
Tags: research

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