ridecamp@endurance.net: carbos, fats, and insulin

carbos, fats, and insulin

Bruce Saul (kitten@resp-sci.arizona.edu)
Tue, 9 Dec 97 01:46:18 MST

Hi, I've been perusing this topic for a while, haven't caught every post,
but I was interested in whether anyone had thought about the insulin angle
with regard to carbo-loading in horses.
My mom was hypoglycemic, to the uninitiated this is low blood sugar,
in essence the opposite of diabetes (though the two are intertwined by
genetics, both genes seem to be located close to each other on the same
chromosome). Low blood sugar is a condition which results when the body
for whatever reason overreacts to severe doses of sugar coming into the blood
and releases too much insulin, kind of an insulin panic attack. In people
who have this condition the universal treatment is to tell them to eat
frequent small meals that contain very little if any short-chain carbos,
i.e. sugars or easily digested polysaccharides. Carbo loading for these
people must consist of things like pasta, or rice, no muffins, no energy
bars, no fruit, in short nothing that can be digested quickly to go into
the blood stream quickly. In fact they are told to make their diet high
in proteins because those take longer to digest and will make blood sugar
entering the blood stream more consistent. The object is to deter sugar
spikes in order to deter the offending insulin spike. The result of
an insulin spike is low blood sugar and low energy, irritability (man are
they irritable) and an inability to concentrate.
To bring this around to horses, to me horses have always seemed like
the ultimate hypoglycemics (I realize that this may just be a perception but
bear with me), they do best with constant high fiber eating, they can't
handle the digestion of carbohydrates well (they're really very poorly
designed for them unlike humans), they can't handle long periods of
abstinance from food, and they can become toxic if they overindulge in carbos.
The things that long distance riders, and horse haulers have known for
many years is that horses on long distance rides don't do well with high
carbohydrate diets, horses being hauled long distances should not be grained
for the same reason, it puts an additional stress on a stressed system
because of their poor digestive system with regard to carbohydrates. No
grain on a long trip is the recommendation. Endurance riders experiences
would seem to indicate that their horses do best when they eat hay and
grass but not if they feed grain.
Recently there has been some additional data about feeding fats.
In looking at some things that have appeared in magazines on humans as well
as horses recently I find that some studies are showing that human marathon
runners do better on a higher fat diet, as high as 50% fat seems to provide
greater stamina for human runners, carbo-loading seems to be fading as
the thing to do for humans. I would speculate that some human runners may
find that because of mild hypoglycemia carbo loading would not do those
runners much good, they would find that about a half-hour to an hour after
loading their energy might fail them. This does not mean that the majority
would have this condition but other factors may be involved. None of the
articles said to load on fat, merely that a low fat diet seems to be
associated with poor stamina in human runners, a higher fat diet is associated
with better stamina. In horses there was a recent article on feeding fat
with regard to horse activity, energy, and behavior in Equus. The article
didn't elaborate but said that a study conducted at one vet school using
sweet feed for calories vs. fat for calories and using the same horses
showed that when horses were fed sweet feed they were more nervous and stall
walked more than horses fed fat. That nervous energy may be good in a horse
racing short distances on a track but it has been shown to be detrimental in
an endurance horse. I believe the article said the horses also seemed to
concentrate better during training when on fat vs. carbos. Endurance riders
have also reported better stamina in horses fed additional fat in their
diets. Finally I have read that one of the problems with carbo loading,
especially with sugars is not just that serum blood sugar can spike and
then fall rapidly due to insulin overload, but also that shortly after
the rush from the sugar kicks in the neuro-transmitter serotonin is released
into the blood, and the serotonin causes people to become sleepy, not
exactly useful for an athletic activity.
So could it be that we are seeing the effects of hypoglycemia
in horses? Has anyone done any studies on insulin secretion by horses
with regard to carbohydrates? Could this be one of the reasons that
endurance horses tend to do better when fed additional fat for energy than
with additional carbohydrates? Is it possible that fat has an effect on
the slow continual release of blood glucose so that an insulin rebound effect
isn't seen in equine long distance athletes as well as in human long distance
athletes who consume it? Finally while we know that a muscle is a muscle
and human muscles and equine muscles are essentially the same with regard to
how they function can we then ignore the fact that human and equine
digestive systems are very different -- a horse simply cannot eat the amount
or quantity of fat, protein, and carbos a human can eat and a human simply
cannot eat the amount of roughage a horse can take it -- and not take that
factor into consideration?
Food for thought.

Tracy and everybody

Tracy Scheinkman
Misty Mountain Arabian Sport Horses
Tucson, AZ

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