The most common cause of Meniere's disease results from a decreased blood flow around the eustachian. This can be from a vertebrae being out, stress (increases blood vessel constricting epinephrine), smoking, blood vessel constricting drugs like ibuprofen (Advil, Motrin, Nuprin, etc.), and other causes of blood vessel constriction or blockage.
Magnesium can help in some cases since it relaxes blood vessels by displacing calcium, which contracts blood vessels.
If the neck is out then a chiropractor can help.
If the problem is inner ear damage then there is not a lot you are likely going to be able to do.