[Sherman Logan]

The reason they began putting wheat into everything was to counter thiamine deficiencies in this country, particularly in the south.

I think you're mixed up. Beriberi is the deficiency disease for thiamine (B1), and is most often caused by people eating rice and not much else. Never been much of a problem in US.

Pellagra is the deficiency disease for niacin (B3) and is most common among people who eat corn (that hasn't been nixtamalized) and not much else, which used to be pretty common in the American South.

I seriously doubt anybody in America today has such a restricted diet that pellagra is a serious issue. Unless they decide to.

[MarMema]

Well thanks for the correction.