sridd...@aol.com wrote:
(...)

This is a bit like saying 'I'm not a racist, but...'...!

So, that's 8 times the price for half as much? (How does it differ from
human-grade L-lysine, I wonder?)

Indeed. It's cheap. I think 500mg may be a popular dosage because
that's the common gelcap size (for human use). Whatever works.

S.

I think you mean Viralys- 1.25 ml (1/4 teaspoon) contains 250 mg of
L-Lysine.  A 5 oz tube cost about $7-8.

Phil

(...)

Well, they have different functions, and they can't entirely be lumped
together in terms of safety (although all may be considered 'safe' in
general terms).

Caveat: Pretty much all I know about aminos is in the context of humans
and amino supplementation for sport and related stuff (e.g.,
http://www.sportsci.org/jour/9901/rbk.html). People are very cavalier
in their supplementation doses, taking many grammes of some aminos,
with (possible) benefit and (rarely) problems. Problems AFAIK seem to
be mostly due to impurities in poor examples of such supplements -
metals AFAIK. Also, GI issues are possible with large doses.

I have not heard of any reports in any context of L-lysine toxicity per
se; I have heard of problems with some other aminos, but rarely. There
will be the usual issues from feeding (excess) protein, but given that
cats are designed to deal with lots of protein and bits thereof, I
would expect problems to be less likely in cats than in humans.

Some more info (in humans) here:
http://www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/lly_0166.shtml

There's also a paper I've not read (Flodin 1997; J Am Coll Nutr 16:
7-21) all about L-lysine, which states in the asbtract 'Data on
toxicity are reviewed and recommendations made regarding safety of
chronic dosage levels.'. If I remember when I'm next in the library
I'll grab a copy. I expect this paper will not note any cases of
toxicity, either.

But: Being cautious is good - there's certainly no harm in starting at
250mg and then increasing the dose if no effect is seen - but there's
no evidence for 250mg as a kitten dose, or whatever, nor any evidence
that worrying over the dose is time well spent. (Unless you decided to
feed 83g or somesuch).

S.

Too much lysine can affect another amino acid Arginine because it competes
with arginine- IOW, increasing lysine decreases arginine (which the
herpesvirus needs to replicate). Arginine detoxifies ammonia in the cat's
kidneys- low arginine levels can lead to severe hyperammonemia, coma and
death.  Arginine is also important for the heart and pancreatic function and
intestinal health.

Phil