Here is an article on why you should not regularly supplement with vitamin C. It makes sense to me. I hope you find it at least informational or helpful.
Why adding Vitamin C to your dog's diet is
not always a wise thing to do…(This article is also available as a simple text file version)
The dog's internal production of Vitamin C (Ascorbic Acid)
In their bodies, dogs produce about 40 milligrams of this vitamin per kilogram
bodyweight - or 18 milligrams per pound. A 40-pound dog thus produces the
equivalent of about two big tablets (500 milligrams) per day! A dog the size of a
human would produce about 6-8 of those big 500-mg tablets per day - a huge dose,
even compared to what a human needs!
Research has shown that, for dogs as well as for people, a large overdose of Vitamin
C can significantly boost the immune system and help the body to a fast healing of
many injuries.
Form there, it makes sense to conclude that extra Vitamin C is good for people. But
it does not make sense to make the same conclusion for dogs…
Some fundamental body chemistry
In order to understand this, you need to understand some fundamentals of
chemistry. Let consider two chemicals, A and B, who react with each other to
produce the products C and D. Let's assume we have a nice equilibrium with A and B
in balance with C and D:
A + B C + D
This means that every time a molecule of A meets a molecule of B, they may
combine and produce C and D - or depart again as A and B. Same thing with C and
D. When two representatives of them meet, they may react with each other and regenerate
A and B. But they could also remain C and D. We have equilibrium when
we cannot measure any changes of the total concentrations of any of the four
chemicals. That equilibrium is maintained through a constant chemical activity
through two reactions that exactly oppose each other.
When we have achieved equilibrium, we can watch what happens when we add more
of A to the mixture of the four: This will greatly increase the chances of a B molecule
meeting an A molecule, so we will have a greater likelihood of B molecules reacting
with A molecules. The result of this will be that our addition of A will consume a big
chunk of what was left of B - and produce more of C and D!
But if we instead add a large amount of C, then the process will "run the other way",
and the excess amount of C will react with a big portion of D to generate more of
both A and B.
So, in essence, when we add C, the result in the body is a reduction of D!
The problem with supplementing…
The bad news is that we do not know in detail the specific chemical reactions in the
dog's body that produce Ascorbic Acid, which could be chemical C in our example
above. We also do not know what other chemicals are generated along with Ascorbic
Acid in the process - the D's are unknown. Some of them could be very important
for the dog's metabolism, though - we don't know!
But we do know that, whatever those D's are, they will cease to be produced when
we add significant amounts of Vitamin C to our dog's diet! And we do know that
when we constantly supply Vitamin C to a dog, it will shut down its own ability to
generate this vitamin, maybe permanently.
Getting the perspective right
Now, 18 milligrams per pound body weight is quite a lot... You cannot feed enough
fresh fruits to ever reach more than about few percent of that! So, feeding fresh fruit
will not cause a shutdown of the body's internal productions.
However, there are many people who have seen great effects of using Vitamin C
supplementation in large doses to deal with a specific problem, like an infection or
injury, and they then conclude that it is great to continue doing it....
On a temporary basis, this can be OK. But the chemical laws involved in this are as
fundamental as gravity - there are NO EXCEPTIONS! The danger, of cause, is that
you may not see the effects of the shutdown immediately - in fact, you might not see
it until many months or years later, and then you will have no clue about connecting
the problem to your supplementing an unnecessary ingredient.
The bottom line is that you should NOT add vitamin C to a dog's diet at all, unless
you have a very specific acute target (infection, injury) as the reason. In those cases,
please help your dog fight the infections faster by giving it some huge amounts of
Vitamin C over the few days it takes to get well - and then stop the supplementing
again! Use it as you would take antibiotics for yourself.
Mogens Eliasen
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Mogens Eliasen holds a Ph.D. level degree in Chemistry from Århus University, Denmark and has 30+
years of experience working with dogs, dog owners, dog trainers, and holistic veterinarians as a coach,
lecturer, and education system developer. He publishes a free newsletter "The Peeing Post" containing lots
of tips and advice on dog problems of all kinds, particularly about training, behavioral problems, feeding,
and health care.
For more information about Mogens Eliasen, including links to other articles he has published, please send
a short e-mail to
contact@k9joy.com.