To      : Deborah
Re      : Vitamin A toxicity

There have not been many studies on the transmission of vitamin A to
breastmilk, particularly under various conditions such as heavy maternal
supplementation.

First,  toxicity from overdose of Vitamin A is well known and it has actually
killed a number of adult individuals.  The oil soluble vitamins, particularly
vitamin A (90%) are stored for long periods in the liver,  and with continued
overdose,  they are extremely hepatotoxic as well as produce intracranal
hypertension. Whereas toxicity from doses less than 100,000 IU per day are
rare, this depends totally on the health status of the adult individual.
Hypervitaminosis A is known to occur at much lower doses(4000 IU) in
individuals with renal problems.

Vitamin A in infants is also toxic in overdose,  leading primarily to
hepatotoxicity and elevated intracranal pressure (bulging fontanelles).

Apparently,  the amount transferred into milk is tightly controlled by the
alveolvar epithelium and taking higher doses may not necessarily transfer (at
higher levels) to the milk in the normal mother.  This may be controlled in
part by the amount in plasma however, so that once the liver stores are
overwhelmed, plasma levels (and hence milk levels) could rise. But we know very
little about this transfer at this time.

Unfortunately, this area is somewhat obscure, and excessive dosing of vitamin A
should never be recommended.  While infants can take "single" large doses
(50,000 units as in one African Study to prevent blindness) with minimal
increase in intracranial pressure,  prolonged exposure to high doses may be
extremely dangerous (Agoestina JH.  Bull. WHO 72:859, 1994).

So, I would concur with most medical sources,  that chronic doses above
5-10,000 IU per day should be strongly discouraged.  There are suggestions that
chronic hypervitaminosis A can lead to "Chronic" liver failure.  So vitamin A
is not without hazards.

Regards
Tom Hale, PH.D.