Highly branched cyclic dextrin (HBCD) is a carbohydrate popular in sports nutrition supplements. Athletes use it for a source of energy that is fast-acting and easy on the digestive system. HBCD is often marketed as a superior alternative to traditional sugar-based sports drinks due to its unique molecular structure. It provides sustained energy without causing the gastric distress or sharp blood sugar fluctuations associated with some other carbohydrate sources.
Defining Highly Branched Cyclic Dextrin
Highly branched cyclic dextrin is a complex carbohydrate, or polysaccharide, derived from the breakdown of starch, typically waxy maize or corn starch. It is created through an enzymatic process that breaks down the amylopectin component of the starch. This results in a unique, helix-shaped, globular molecule.
The defining characteristics of HBCD are its high molecular weight and narrow molecular weight distribution. It is highly soluble in water and provides a solution with very low osmolality. Osmolality refers to the concentration of particles in a solution; a low concentration means the solution exerts less osmotic pressure. This low osmolality directly influences how the body processes HBCD.
How HBCD Works in the Body
The mechanism that distinguishes HBCD is its effect on gastric emptying, the rate at which fluid leaves the stomach and enters the small intestine. Due to its low osmolality, an HBCD solution passes through the stomach quickly compared to solutions containing simple sugars like glucose. This rapid transit minimizes the time the carbohydrate solution sits in the stomach, reducing feelings of fullness or gastric distress during exercise.
Once HBCD reaches the small intestine, digestive enzymes gradually break down its complex cyclic structure. This allows for a sustained and steady release of glucose units into the bloodstream. The combination of rapid gastric emptying and controlled glucose release provides a continuous energy supply. This avoids a significant spike in blood sugar and subsequent insulin response, which is beneficial for maintaining performance during prolonged activity.
Practical Use and Timing
HBCD is water-soluble, making it easy to mix into beverages without clumping or a thick consistency. Its neutral flavor profile makes it versatile for combining with other supplements, such as electrolytes or amino acids. Consumption typically revolves around the exercise window to optimize energy availability and recovery.
Timing Uses
For pre-workout fueling, HBCD can be consumed to top off glycogen stores before a session. Intra-workout consumption is most frequently utilized during prolonged exercise, providing a steady stream of glucose to delay fatigue. Post-workout, it is effective for rapidly replenishing muscle and liver glycogen stores, which accelerates recovery. Dosing recommendations often fall within the range of 15 to 45 grams per hour of exercise, adjusted based on activity duration and intensity.
HBCD Versus Other Sports Carbohydrates
The primary distinction between HBCD and other common sports carbohydrates, like dextrose and maltodextrin, centers on molecular size and osmolality. Dextrose is pure glucose, a simple sugar with a high osmolality, while maltodextrin is a chain of glucose units that also has a relatively high osmolality. Both simple sugars and straight-chain starches can delay gastric emptying if consumed in high concentrations, leading to gastrointestinal upset.
HBCD’s unique cyclic structure and high molecular weight result in significantly lower osmolality than an energy-equivalent solution of glucose or maltodextrin. This difference allows HBCD to empty from the stomach faster, minimizing discomfort and bloating during intense exercise. Furthermore, while dextrose and maltodextrin tend to cause a rapid surge and crash in blood sugar, HBCD facilitates a slower, more sustained increase in blood glucose, providing a more reliable and prolonged energy curve.