Fructose: Good or Bad?
What Athletes Need to Know
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 source of
glucose to fuel your muscles.
When athletes train heavily or compete, it is important that they replace any
used glycogen stores between bouts of exercise to enable optimal
performance in later events. They also need to get a lot of
carbohydrate, in the form of fructose and other carbohydrates, into their
bloodstream quickly during and after exercise so that their liver and
muscles can use it as fuel.
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 is thought to have a
maximum capacity for glucose transport because it can only transport
around one gram of glucose per minute. Fructose, however, can be
transported into the bloodstream using a different “door”, called GLUT5.
By using both routes, rather than just SGLT1, athletes can increase the
amount of ingested carbohydrate the body can use during exercise.
If you don't use fructose then your 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.