There are also recommendations that include avoiding caffeine, alcohol, smoking and stress (how this latter is avoided when you feel so rotten I don`t know). Other suggestions tend to be contradictory; some say plenty of sleep, others plenty of exercise. I think it may be more of a case of doing what makes you feel better.
After a series of severe attacks my GP prescribed some medication that was ineffective, and then prescribed betahistine dihydrochloride (3x16mg per day) which I have found very effective - only 3 mild attacks in nearly 3 years. The drug is also known as Serc. It is not approved by the FDA in the USA, and so is not mentioned on most US medical websites. It is not approved by FDA because it cannot be proved to work, because Menieres attacks happen at unpredictable, often long, intervals, so those taking the drug might not be going to have an attack anyway.
Plenty of information including a book download and lifestyle suggestions on click here.
and I'm saying it again - nobody here is qualified to give any kind of medical advice, and your wife should not follow any advice you see in this thread without first consulting her doctor.
It's fine for people to recount their personal experiences,or to suggest other sources of information, but that's as far as it goes. People react differently to medical treatments - even when suffering from the same complaint.
I think the FE is just covering himself, as is only right, and just making sure that you realise that any advice given is not necessarily good for your wife and that any "suggestions" should be checked with the doc first. Sorry if that sounded like preaching, I'm sure you realise this is the case.
I wish I could help my friend but sadly I know nothing of this ailment, but do wish you luck with sorting things out.