Effect of tea consumption on oxidative stress and expression of DNA repair genes among metal press workers exposed to occupational noise.

Several studies have shown that tea consumption is associated with beneficial effects on human health, which is mainly explained by the antioxidant properties of tea. However, evidence on the effect of nutrition interventions on oxidative stress in an occupational setting is limited. Therefore, the present study aimed to investigate the effect of tea consumption on oxidative stress in noise-exposed metal press workers. The study sample comprised 24 metal press workers and 24 age-matched control subjects. Metal press workers were assigned to the intervention group consisting of a glass of jujube tea and a portion of raisins per day for 4 weeks. Full-shift noise dosimetry was performed to measure noise exposure with average noise levels of 89.91 ± 2.92 dB for metal press workers and 61.54 ± 1.03 dB for control subjects. Elevated levels of baseline oxidative stress were observed in metal press workers compared with control subjects as indicated by significantly decreased levels of total antioxidant capacity (TAC) (P = 0.026) and total thiol groups (TTG) (P = 0.0001), whereas no significant difference was observed in case of malondialdehyde (MDA). Intervention with jujube tea and raisins in metal press workers led to a decrease of oxidative stress as displayed by increased levels of TAC and TTG (P = 0.0001) as well as decreased levels of MDA (P = 0.012). Moreover, the intervention significantly altered expression of repair genes in metal press workers as demonstrated by decreased levels of OGG1 (P = 0.0002) and ITPA (P = 0.009), whereas no significant difference was observed in case of MTH1. These data suggest that regular tea consumption may protect occupational noise-exposed subjects from oxidative damages.