[Anotheroneagain]

The opposite should be investigated as well. The deficiencies in nutrients like copper, selenium or molybdenum are generally only known in animals, and rarely investigated among people. Copper deficiency can cause various symptoms like weight loss, loss of pigment, indigestion, or neurological problems. It seems that molybdenum deficiency shifts the symptoms towards neurological, while the rest happens from copper deficiency alone.

[pjc50]

I think some people have been talking about selenium deficiency since the 1970s. The trace metals are something of a problem since it's also possible to have harmful effects from too much.

[stef25]

Why would these deficiencies occur in one specific geographical area ?

[nucleardog]

All of the milk in Canada is fortified with vitamin D because the population is more at risk of vitamin D deficiency due to geography. (Less sunlight for more of the year.)

So it's not entirely _impossible_, but I agree it doesn't seem very likely.