Questions about metabolism: Vitamin B 3 helps metabolic function, without B3 would an organism fail to grow or

Question

thrive? If deprived of this will the organism be permanently premature and dwarfed? Will larger amounts cause the organism to metabolize faster?

Answer 1

Deficiency of B3 causes pellagra, but the entries don't seem to say anything about growth retardation.  

I would guess that a major deficiency for an extended time during development might cause permanent small stature, but that in most developed countries this would be rare because most small stature kids who were sick due to deficiency would be seen by doctors and treated.

As for speeding growth or development, I would again guess that there might be some effect, but maybe not a very pronounced one.  Also, one should be careful not to overdo it with vitamins because in some cases they can become toxic at high doses - and the phenol ring in B3 makes it look like it could be one of those.