Some wild ass speculation posted for further discussion:

[hedgehog]

1. We know the old recommendation for Vitamin D was based on how much was needed to avoid rickets, an acute disease.


2. Recently, medical scientists have proposed much higher recommendations based on prevention of chronic disease and/or improvement of the immune system, etc.

3. What if Linus Pauling was right about Vitamin C?

[Warpy]

1. 3. He wasn't, that one has been tested to death

The minimum daily requirement is the level at which vitamin deficiency diseases won't occur. The recommended daily allowance is above that, but not by much.

Science is marching on and the role of vitamins has continued to be researched beyond their role in curing deficiency diseases. Vitamin C didn't do much of anything when the RDA was exceeded. Vitamin D did.

Linus Pauling and Albert Szent-Gyorgyi were both scientific powerhouses who managed to get a lot of research into Vitamin C funded in their lifetimes. Most of it came up empty, especially regarding the functioning of the immune system in high doses. It does, however, prevent scurvy and is an essential nutrient.