I must admit that my understanding of chemistry is very rudimentary at
this point. I wouldn't call it a complete ignorance, but I did pay
attention in my elementary science classes, for what that is worth.

I was referring nutrients as those substances which are required by an
organism to support itsself. also, I feel that Webter's definition of
nutrient is an oversimplification. Remember that the purpose of a
dictionary is to define language as it is used, not to dictate its use.

I am a bit limited in resorces, including time for study, as I am in
the middle of a disaster area, so it may be some time before I can
check out some of the references in these posts.

I looked up the wikipedia article on nutrients and it splits them into
substances which provide energy and substances which support
metabolism. The chemical elements of which you speak would fall under
one or the other of these groups. unfortunately, the article uses
confusing language in places and is severly lacking references. The
discussion thread for that article would probably be a better place to
hash out an exact meaning.

Anyway, I hope that my input can be of some use.