From http://www.althealth.co.uk/services/...amin_b12_2.php

A vitamin B12 deficiency can raise blood levels of homocysteine, an amino acid that is thought to be toxic to nerves. Low levels of B12 have been linked to a number of nervous system disorders, including memory loss, decreased reflexes, impaired touch or pain perception--and, apparently, tinnitus and noise-induced hearing loss.


Researchers from the Institute for Noise Hazards Research and Evoked Potentials Laboratory at Chaim-Sheba Medical Center in Ramat Gan and from Tel Aviv University, both in Israel, looked at a group of 385 people with tinnitus and found that 36 to 47 percent suffered from vitamin B12 deficiency. All of the people low in B12 received injections of 1,000 micrograms weekly for four to six months. At the end of that time, their hearing and tinnitus were evaluated. Fifty-four percent reported improvement in their tinnitus, and approximately one-fourth reported reductions in the measured loudness of their tinnitus, according to Joseph Attias, D.Sc., head of the institute and one of the study's main researchers.


"vitamin B12 deficiency is somehow associated with chronic tinnitus," says Dr. Attias. "Long-term exposure to noise may deplete body levels of B12 and so make the ears more vulnerable to noise-induced damage."


Most of the people in this study had tinnitus for six years or longer. "It's possible that people who are treated earlier for vitamin B12 deficiency may have more improvement in their tinnitus than occurred in this study," says Dr. Attias.


If you have tinnitus, and especially if you also have memory problems, ask your doctor to check your blood level of vitamin B12, he suggests.