When I was in college and having a lot of trouble with Bipolar disorder, I saw several different psychiatrists.
One of the stranger psychiatrists that I saw believed in a holistic approach, and in addition to medications, recommended that I take a zinc supplement. I believe it also had copper in it, but my memory is a bit hazy.
I took the supplement for awhile, but didn't really believe in it, and my symptoms were pretty strong at the time, so my focus was on taking some pretty strong medication. Whether the zinc did anything for me then, I couldn't tell.
Well, fast forward to today. I've been taking zinc for the last week because I have a cold. Without a doubt, zinc helps sore throats, and since I've been having a little bit of a sore throat and eustachian tube soreness, I've been trying to take zinc to help fight it off. I am also taking garlic and vitamin A. This regimen comes from past experience and is relatively cheap.
So my cold is staying on the mild side, and I'm hoping that it doesn't progress into a big infection. At the same time, while I've been taking this zinc, my mood has been staying really smooth. Is there a connection? I don't know, but maybe I'll keep taking it even after the cold passes. Maybe my strange psychiatrist knew what he was prescribing :)
One thing to be aware of, is that taking too much zinc can be bad for you. Here's some basic information on what you need to know about taking zinc. I see that website says that the upper dose for zinc should only be 40mg for people my age. Oddly, that contradicts the guidelines on my bottle of Zinc Lozenges (it says no more than 138mg in 24 hours). Other places I've read no more than 100mg or 125mg, or that it depends on your body weight. It seems that taking the lowest amount that works would be a good idea. I've noticed that 25mg and 50mg are the doses that are commonly sold as supplements.
There is actually quite a bit of information on the connection between zinc deficiency and depression and other mood problems.
Here are a few links:
The role of zinc in neurodegenerative inflammatory pathways in depression
Zinc Enhances Antidepressant Therapy
An animal study showing zinc works as an antidepressant
That's just a sampling. If you search Google for Zinc Antidepressant, you will find a wealth of information. However, "zinc" and "mania" and "zinc" and "mood stabilizer" don't bring up any useful results, so perhaps zinc only helps the down side of bipolar symptoms.