Does Oral Monosodium Glutamate Have a Cochleotoxic Effect? An Experimental Study

Area of Science:

• Ototoxicology
• Neuroscience
• Food Science

Background:

• Monosodium glutamate (MSG) is a widely used food additive.
• The cochlear effects of oral MSG consumption remain largely uninvestigated.

Purpose of the Study:

• To investigate the potential cochleotoxic effects of oral MSG in guinea pigs.
• To evaluate MSG's impact using electrophysiological, biochemical, and histopathological methods.

Main Methods:

• Guinea pigs received daily oral MSG doses (100 mg/kg or 300 mg/kg) for one or two months.
• Auditory function was assessed via distortion product otoacoustic emissions (DPOAE) and auditory brainstem response (ABR).
• Perilymph and blood glutamate levels, along with cochlear histopathology, were examined.

Main Results:

• Significant changes in DPOAE signal-to-noise ratio were observed at specific frequencies in the high-dose MSG group.
• While ABR wave latencies showed no significant difference, ABR thresholds tended to increase.
• Histopathological analysis revealed moderate-to-severe degeneration in cochlear hair cells, support cells, and spiral ganglia.

Conclusions:

• Oral MSG administration, at doses and routes relevant to human consumption, may induce cochlear toxicity.
• MSG exposure can lead to structural damage within the cochlea.
• Further research is warranted to understand the full implications of MSG on auditory health.