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NITROGEN BALANCE THE AMINO ACID POOL
Nitrogen balance is one of the phrases you will hear batted around all of the
time when you begin looking into the realm of exercise training and nutrition.
But what exactly is nitrogen balance and why is it so important?
Nitrogen is provided by all proteins. Exercise causes the body to use proteins
at a much faster rate than at rest. Now, a positive nitrogen balance means that
the body is obtaining sufficient proteins from the diet that you are supplying.
Whenever your body slips into a negative nitrogen balance this is the state
where your body has insufficient input of protein and is therefore cannibalising
muscle and other protein structures to provide its daily needs. You don't need
to be a rocket scientist to understand that this means that all of that time
and effort you spent building that muscle up is being flushed down the toilet,
as your body literally eats its own muscle to provide the proteins it requires.
A study performed by Gontzea at the institute of medicine in Bucharest (1974)
shows us that athletes instructed to stop exercising and remain sedentary for
2 weeks, and were given a daily intake of 1 gram of protein per kg of bodyweight
(this being 33% above the RDA). Now so long as these athletes remained sedentary
they maintained a positive nitrogen balance. When these subjects were returned
to their two hour daily workouts, within two days, nitrogen balanced dropped
into a negative state. This means they began breaking down their own muscle
tissue as opposed to building it up as you would hope for from regular intense
training.
Dr Peter Lemon et al, at the Kent State University Ohio (1989) repeated the
above Gontzea study and found that endurance athletes in regular training required
1.14 - 1.39 grams/kg of bodyweight daily to remain in a positive state of nitrogen
balance.
There is absolutely no doubt that a very high protein diet of around 3.0grams
per kg of bodyweight per day maintains a highly positive nitrogen balance. But
the use of nitrogen for building muscle is not controlled by the protein that
you eat, it is controlled by the liver that holds the available store at precisely
the level required to meet daily demands, and all excess protein is simply broken
down as it is not needed.
So theoretically there are no additional benefits to consuming an intake of
protein above and beyond what your body is in demand for, with the exception
of dietary manipulation in order to achieve certain specific health or fat loss
goals.
It is also worthwhile to note that excess protein fills your blood with more
than the amino acids that make it up. And excess amino acids are converted into
highly toxic ammonia.
One thing that you should bear in mind when it comes to choosing the quality
of your proteins is that a deficiency in just one amino acid results in a negative
nitrogen balance - more protein is degraded than is synthesised and so more
nitrogen is excreted.
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