Fructose: Good or Bad? What Athletes Need to Know
How fructose improves performance in endurance athletes
Fructose sometimes gets a bad rap for endurance athletes because it is thought to cause stomach and GI discomfort. Like anything else, if you take too much fructose it can be a problem. But if you use it properly it can actually significantly improve performance … without stomach issues.
Here’s why:
Most of the energy that we use during endurance sports comes from consumed carbohydrates that are converted into glycogen and stored in our muscles. Glycogen can then be quickly broken down into glucose and used to fuel the muscles. The liver also stores glycogen which has been converted from fructose and serves as an additional “fuel tank” to power your muscles.
here's where it gets interesting
The main route for glucose absorption from the gut is through a transporter called SGLT1 – a protein that acts like a door, helping glucose go from the gut to the bloodstream. SGLT1 has a maximum capacity and can only transport around one gram of glucose per minute (240 calories/hour). Fructose, however, is absorbed with a different transporter, called GLUT5. By using both transporters you can increase the amount of carbohydrate the body can use during exercise up to approximately 300 calories/hour.
GLUT5’s sole job in life is to transport fructose, so if you’re not consuming fructose then you’re not using the GLUT5 transporter … it’s like have an additional fuel line and not using it, why would you do that? In addition, your secondary fuel tank (your liver) will be under utilized as well.
The rapid absorption of fructose mixtures and special handling of fructose in the liver are the two main reasons that fructose can also help to speed up recovery after exercise. A recent study found that when athletes drank sports drinks containing both fructose and complex carbohydrates after exercise, they accelerated the recovery of their liver glycogen stores. It almost doubled this rate of recovery compared with drinks that didn’t have fructose, when the same total amount of carbohydrate was consumed.
bottom line
If you want to “be your best”, incorporate some fructose into your training and competition nutrition program.
Both e-Gel and e-Fuel are formulated with this in mind. The main ingredient in our products is maltodextrin, a complex carbohydrate from corn. Added to the maltodextrin is fructose in levels that can be efficiently processed and stored by the liver, thus supplementing your total available energy without causing stomach issues.
fructose research references
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