Vitamin B12 has shown no toxicity to animals at several thousand times their nutritional requirements. In man, pernicious anemia patients have received daily doses for years 10 to 20 times that of the highest estimate of average daily consumption. The only reaction to vitamin B12 so far demonstrated in man is the development of sensitivity that can become manifest as allergy or anaphylaxis after parenteral administration of relatively high doses.
Vitamin B12 absortion is pecific and limited, so that only a very small proportion of vitamin B12 given orally becomes physiologically available and active. The body stores are depleted very slowly because of enterohepatic recirculation.
The addition of vitamin B12 to food, in amounts far in excess of need or of absorbability appears to be without hazard. On the basis of available evidence, the Select Committee concludes that: There is no evidence in the available information on vitamin B12 that demonstrates, or suggests reasonable grounds to suspect, a hazard to the public when it is used at levels that are now current and in the manner now practiced, or that might reasonably be expected in the future.