Cyclodextrins are discussed in the sources as potential supplements for athletes, with information provided on two main types: Highly Branched Cyclic Dextrin (HBCD) and Alpha-cyclodextrin (αCD).

Highly Branched Cyclic Dextrin (HBCD), often referred to as Cluster Dextrin, is described as a complex carbohydrate derived from starch that has high digestibility and absorption rates, allowing for relatively quick bioavailability of D-glucose molecules in the bloodstream. It is noted for providing better gastric emptying processes and a favorable glycemic response compared to some other carbohydrate formulations. The properties of HBCD may be beneficial for athletes in high-intensity sports, such as weightlifting, by potentially providing faster glucose availability without significantly increasing insulin levels, and for athletes in long-duration exercises by potentially reducing gastrointestinal discomfort. However, a study investigating the effects of a 30g intake of cyclodextrin (Cluster Dextrin) during CrossFit® training did not find significant metabolic or performance effects in general CrossFit tests, although some differences were observed in specific tests like countermovement jump power. The data regarding performance improvements from this specific study were not conclusive, and further research is needed.

Alpha-cyclodextrin (αCD) is a different type of cyclodextrin, described as a cyclic hexasaccharide composed of six glucose units. Unlike HBCD, αCD is not digested in the human small intestine but is completely fermented by gut microbes. Studies in healthy, active non-athlete men have shown that supplementation with αCD significantly improved endurance exercise performance, specifically the 10 km biking time trial, compared to a placebo group. αCD supplementation was also associated with a significant reduction in post-exercise fatigue and a suppressed heart rate increase during exercise. The potential mechanism for these benefits may involve gut bacteria that ferment αCD to produce short-chain fatty acids like propionate, which could facilitate hepatic glucose production for energy during exercise. αCD is considered a safe substance and may serve as a supplement to support endurance exercise performance and reduce post-exercise fatigue.

Highlighting the difference between cyclic dextrin and cyclodextrin: While Highly Branched Cyclic Dextrin (often called Cluster Dextrin) is sometimes referred to as cyclodextrin, the sources note that it is a different molecule from alpha-cyclodextrin.