Effects of Curcumin in Workers with Noise-Induced Hearing Loss: Preliminary Report

Prolonged loud noise exposure causes sensorineural hearing loss through cochlear oxidative stress, requiring heat shock protein 70 (HSP70) for protection. Curcumin boosts antioxidant expression and safeguards the cochlea. Pure tone audiometry (PTA) measures the type of hearing loss and otoacoustic emission (OAE) detects early auditory issues. This study evaluated the impact of Curcumin on noise-exposed workers via PTA, OAE, and HSP70.

This preliminary study included 54 noise-exposed workers with hearing thresholds ≥26 dB and SNR values <6 dB. Participants were randomized into three noise-exposed groups: placebo (positive control), 500 mg Curcumin, or 1,000 mg Curcumin for 4 weeks. A negative control group of 18 non-exposed workers with normal hearing who received no treatment, served as an external reference only. HSP70 levels, PTA, and OAE were measured before and after intervention in all groups.

PTA showed a significant worsening of hearing threshold in the positive control group (p=0.001), significant improvement in Curcumin 500 mg group (p=0.046), in the Curcumin 1,000 mg (p=0.059). OAE revealed substantial worsening of SNR in the positive control group (p<0.001) and significant increase in the Curcumin 500 mg (p<0.05) at 4, 7, 8, and 9 kHz, and in the 1,000 mg groups (p<0.05) at 5, 8, and 9 kHz. HSP70 levels significantly increased in the positive control group (p=0.021), both Curcumin groups showed a non-significant increase.

Curcumin was associated with improved hearing thresholds and favorable SNR changes in noise-exposed workers. Changes in HSP70 levels were minimal and not statistically significant in the curcumin groups.