Reduction in noise-induced temporary threshold shift in humans following oral magnesium intake.

A previous study demonstrated the prophylactic effects of magnesium on noise-induced permanent threshold shift in humans. For the first time, this study explores the effects of magnesium on temporary threshold shift in 20 human subjects, all men (16-37 years, mean age 21 years). The study was conducted in a double-blind manner on the same subjects tested in three different phases (placebo, magnesium, no-drug). The cochlear changes were assessed using both behavioural (audiograms) and objective (otoacoustic emission) measures. Blood samples were collected at the beginning and end of each phase. Amongst subjects and phases, magnesium intake was associated with significantly lower temporary threshold shift, compared with the other two phases, which were reflected both by the behavioural and cochlear measures. A correlation was found between the blood magnesium levels and temporary threshold shift reduction. No side-effects were associated with the oral ingestion of the magnesium. Magnesium provides significant protection against temporary threshold shift, complementing the previous permanent threshold shift human study. Both human noise-induced hearing loss studies introduced a novel, biological, natural agent for prevention and possible treatment of noise-induced cochlear damage in humans.