Types of carbohydrates and their intestinal absorption

Carbohydrates They are molecules made up of carbon, hydrogen, and oxygen. They can be classified according to their degree of polymerization and can initially be divided into three groups:

● monosaccharides;
● disaccharides;
● oligosaccharides;

Glucose, fructose, and galactose are the monosaccharides present in the diet. Glucose is the only one that can be oxidized in muscle to produce energy. Fructose and galactose must be converted to glucose in the liver and then oxidized. The most important disaccharides in the diet are sucrose, which is a combination of glucose and fructose, lactose, and maltose.

In addition to the amount of carbohydrates, the type of Carbohydrate is important for adequate performance in endurance training.

Physical research

Different carbohydrate drinks and placebos were tested on cyclists who pedaled for 2 hours on a cycle ergometer at 54% of their maximum oxygen consumption. The researchers used three drinks throughout the trial: water (placebo), a glucose drink (1.8 g/min), and a combined glucose:fructose drink (2:1 with the same oxidation rate of 1.8 g/min).

Cyclists who drank the beverage with the carbohydrate combination performed better, averaging 275W compared to the group that consumed the glucose beverage, which averaged 254W (AP Currel, 2008). This was the first study to demonstrate this effect of different transporters.

Furthermore, other studies have demonstrated a reduction in gastrointestinal cramps in cyclists. In this study, the authors used a maltodextrin:fructose solution (Rowlands, 2012).

The explanation for these positive effects of carbohydrate mixing is related to the gut. Glucose is absorbed via SGLT1 (Sodium-dependent glucose transporter), a transporter located in the intestinal membrane. This transporter has a strong affinity for glucose and galactose.

Fructose is absorbed through another transporter, called GLUT5. When this combination of carbohydrates occurs, the transporters do not become saturated and therefore oxidize more glucose, generating more energy. Another benefit of its consumption is the reduction of gastrointestinal symptoms that affect runners and triathletes.

It's important to remember that SGLT1 transports glucose via a secondary active transport mechanism that is linked to sodium. Without sodium in the carbohydrate mixture, this absorption doesn't occur. Therefore, Xtratus is formulated with a variety of carbohydrates, with an ideal glucose-to-fructose ratio, and contains the necessary sodium and other minerals to restore energy levels and replenish minerals lost through sweat during activity. In addition to stimulating glucose absorption, sodium also aids in water absorption in the intestinal lumen for rehydration during exercise.