Higher zinc and iron intakes may decrease tinnitus risk: Study

A population-based cohort of Australians, aged 50 years and older, was used to determine whether diet is a modifiable lifestyle risk factor for tinnitus.  Researchers observed that tinnitus prevalence was not significantly associated with vitamin and mineral intake. However, lower intake of zinc and iron significantly increased the risk of tinnitus incidence over 10 years by 44% and 35%, respectively.

“This is the first longitudinal study to explore the associative links between dietary intakes of vitamins and minerals and the prevalence and incidence of tinnitus in an older adult population,” wrote researchers from Macquarie University, Flinders University, Westmead Institute for Medical Research, University of Sydney in Australia and the Tinnitus Research Initiative in Germany.

Tinnitus and dietary vitamins and minerals intake​

Tinnitus is a condition where the sufferer perceives a sensation of sounds without actual external source of sound. Individuals with severe tinnitus develop difficulties with attention, sleep, anxiety and depression, which impact their quality of life.

The global prevalence of tinnitus has been estimated​ to be 14.4% in all adults and 23.6% in older adults. Even though most adults with tinnitus are not bothered by its symptoms, some older adults experience significant problems.

The incidence of tinnitus is associated with multiple factors including noise exposure, hearing loss, head injury, genetic factors and inflammation in the auditory pathway. Typically, clinicians treat tinnitus through cognitive behavioral therapy, sound therapy, pharmacotherapy, counseling and education. Since age is a common predictor of tinnitus and inflammation, healthy aging could be explored as an alternative treatment approach or a preventive solution.

Study details​

This longitudinal study recruited 2,947 participants at baseline from the Blue Mountains Eye and Hearing Study II, conducted between 1997 and 1999.  Most participants were female (57%), and the mean age of the cohort was 67.4 years.

A validated semi-quantitative food frequency questionnaire (FFQ) containing 145 food items was used to determine dietary vitamins and minerals consumption of the participants. In this FFQ, participants indicated the frequency of consumption of each food item through nine options ranging from 'never' to '4+ per day'. Researchers linked FFQ data to the Australian food composition tables from 1990 to determine the vitamin and mineral content of each food item.

No association between vitamin and mineral intake and tinnitus prevalence was observed in 32% of the participants who presented tinnitus symptoms at baseline. Approximately 55% of the remaining participants, who did not experience tinnitus symptoms at baseline, were followed up for 10 years to evaluate incident tinnitus.

A lower intake of iron (≤ 9.51 mg/d) and zinc (≤8.48 mg/d) significantly increased the risk of incident tinnitus by 35% and 44%, respectively, compared to those with higher intakes. The recommended dietary intake (RDI) for zinc and iron was found to be inadequate to mitigate the risk of tinnitus.

Commenting on the potential mechanism(s) of action, the researchers noted that zinc possesses antioxidant and anti-inflammatory properties and that its lower intake increases the risk of inflammation in the auditory system. Zinc deficiency could increase the susceptibility to ischemic damage that could impair inner ear functioning, causing tinnitus. A previous study​ also revealed that inflammation of the auditory pathway elevates excitatory neurotransmission and reduces inhibitory ones, which induces neuroplasticity and causes chronic tinnitus. Furthermore, another study highlighted a possible indirect association​ between adequate iron status and tinnitus risk through blood haemoglobin levels.

The researchers noted that the associations recorded in the study were “marginally significant and therefore, conclusions should be drawn with caution.” They called for large population-based longitudinal research to validate the findings and for iron and zinc supplementation trials to show causation versus correlation.

Source: Nutrients​ 
2024, 16​(15), 2535; doi: 10.3390/nu16152535​
“The Association between Dietary Intakes of Vitamins and Minerals with Tinnitus”
Authors: Diana Tang et al.