Introduction
The World Health Organization (WHO) estimated that 466 million people (6.1 per cent of the global population) were living with disabling hearing loss in 2018, and this number is expected to increase as the population ages rapidly.1 In 2019, the WHO estimated the annual global cost of hearing loss to be US$750 billion. This not only causes considerable economic losses but also seriously reduces the quality of human life. Hearing loss has recently been ranked as the fifth leading cause of years lived with a disability.Reference Stika and Hays2 Many large epidemiological studies have found that hearing loss is independently associated with falls, isolation, cognitive decline, dementia, anxiety, depression, social isolation, increased rates of hospitalisation and healthcare use.Reference Jiam, Li and Agrawal3–Reference Blazer and Tucci6 This emphasises the importance of early detection to potentially delay or prevent its onset.
The pathogenesis of hearing loss involves various factors, including microcirculation disorders, viral infections such as rubella and measles, head trauma, genetic factors, noise exposure and autoimmune diseases. These factors can lead to damage or degeneration of the hair cells in the cochlea, disruption of the auditory nerve pathways or impairment of the auditory processing in the brain, ultimately resulting in a decrease in hearing function.Reference Chandrasekhar, Tsai, Schwartz, Bontempo, Faucett and Finestone7
Multiple studies have shown that dietary intake of carbohydrates, cholesterol, fibre, protein, sugar, fruits, vegetables, saturated fats and trans-fats is associated with self-reported hearing loss and requires public health interventions to prevent it.Reference Rodrigo, Campos-Asensio, MÁ, Crespo and Olmedillas8–Reference Chen, Tan, Wu and Liu11 Comprehensive guidelines on healthy eating, however, are lacking. As the concept of dietary patterns continues to develop and evolve, the Healthy Eating Index is widely used in different types of research, including surveillance, epidemiological and intervention studies, involving different populations in the USA. It can be indexed to guide the diet of U.S. for early prevention of hearing loss.Reference Schap, Kuczynski and Hiza12
The Healthy Eating Index is a measure that assesses whether a group of foods meets the Dietary Guidelines for U.S., which measure diet quality rather than quantity, that is, it assesses density rather than absolute quantity, providing a guide to the overall diet.Reference Krebs-Smith, Pannucci, Subar, Kirkpatrick, Lerman and Tooze13 There were no changes in the components or standards between the Healthy Eating Index 2015 and the Healthy Eating Index 2020.Reference Shams-White, Pannucci, Lerman, Herrick, Zimmer and Mathieu14 The relation between the Healthy Eating Index and hearing loss is an important topic in healthcare and public health. In this context, by conducting a retrospective cross-sectional study involving 5171 US adults from the National Health and Nutrition Examination Survey, we sought to clarify the relationship between the Healthy Eating Index and hearing loss in adults.
Materials and methods
This cross-sectional study used National Health and Nutrition Examination Survey data, conducted by the Centers for Disease Control and Prevention, from 1999 to 2012 and 2015 to 2018.15 The purpose of the National Health and Nutrition Examination Survey was to assess the health and nutritional status of non-hospitalised U.S. The National Health and Nutrition Examination Survey collects demographic and in-depth health information through home visits, screenings and laboratory tests at mobile screening centers. The survey was authorised by the National Center for Health Statistics Ethics Review Committee and all participants provided written informed consent prior to participation.
The secondary analysis did not require additional approval from the Institutional Review Board.16 Data from National Health and Nutrition Examination Survey may be obtained through the National Health and Nutrition Examination Survey website (http://www.cdc.gov/nchs/nhanes.htm). Individuals aged over 20 years who completed the interviews participated in our study. We excluded individuals who lacked data on hearing loss, Healthy Eating Index or covariates. The total sample size of adults evaluated was N = 49 312, and the details are shown in Figure 1. Only publicly available data were used in the analysis and ethical approval was not required for the study.
The study’s flow diagram.
The Healthy Eating Index assesses diet quality and refers to how well a group of foods meets the Dietary Guidelines for U.S.17 The Healthy Eating Index 2020 contains 13 components and scoring criteria, and this is the first time that there has been no change in the index; the scores in the Healthy Eating Index 2020 is the same as those in the Healthy Eating Index 2015. Krebs-Smith et al. described the details of each component in the Healthy Eating Index 2015 update.Reference Krebs-Smith, Pannucci, Subar, Kirkpatrick, Lerman and Tooze13
Healthy Eating Index 2015 scores range from 0 to 100 and are graded as follows: Grade A (highest score), total score between 90 and 100 points, indicating that an individual’s dietary nutrient intake is very consistent with dietary guidelines; Grade B, total score between 80 and 89 points, indicating that an individual’s dietary nutrient intake is somewhat consistent with dietary guidelines; Grade C, total score between 60 and 79 points, indicating that an individual’s dietary nutrient intake has room for improvement, but still has a healthy eating pattern; Grade D, total score below 60 points, indicating that an individual’s dietary nutrient intake needs significant adjustment to improve dietary quality; Grade F, total score between 0 and 59 points, indicating that an individual’s dietary nutrient intake is severely inadequate and requires special attention and improvement. A higher score reflects better diet quality. We used day 1 total nutrient intake to calculate the 13 components of Healthy Eating Index 2015.
All hearing tests were performed by a trained examiner on candidates aged 20–69 years in a dedicated soundproof room at a mobile test center. Hearing thresholds were tested in both ears at 7 frequencies (500, 1000, 2000, 3000, 4000, 6000 and 8000 Hz), with observed values ranging between −10 and 120 dB. The pure tone average (PTA) of speech frequency in both ears was calculated as the average of the hearing thresholds at 0.5, 1, 2 and 4 kHz. Good ear PTA is a continuous variable: the higher the value, the worse the hearing. Low-frequency PTA calculations used hearing thresholds at 0.5, 1 and 2 kHz in the better ears, while high-frequency PTA calculations used hearing thresholds at 4, 6 and 8 kHz in the better ears. All hearing thresholds were reported as dB HL.
Sensitivity analysis was performed using PTA with the bad ear rather than the good ear. In addition, good ear PTAs were classified according to clinical cut-off points defined by the 181997 WHO, where a hearing level of 25 dB HL or less indicates normal hearing and a hearing level of more than 25 dB HL indicates hearing loss.19 As defined by the WHO in 2021, hearing loss is defined as the speech frequency of good ear PTA of 20 dB or more and less than 20 dB is normal hearing.Reference Jiang, Spira, Reed, Lin and Deal20
Multiple potential covariates were evaluated based on the literature,Reference Jung, Kim, Cho, Jeon and Song21–Reference Scinicariello, Przybyla, Carroll, Eichwald, Decker and Breysse23 including age, sex, marital status, race and/or ethnicity, education level, household income, smoking status, physical activity, high blood pressure, diabetes mellitus, history of cardiovascular disease, body mass index (BMI) and noise exposure.
Race and/or ethnicity was classified as Mexican American, other Hispanic, non-Hispanic White, non-Hispanic Black or other races, including multiple races. Marital status was divided into married, never married, living with a partner, widowed, divorced or separated. The level of education was classified as less than 9th grade, 9−11th grade (including 12th grade with no diploma), high-school graduate and/or General Educational Development or equivalent, college or Associate of Arts (AA) degree, or college graduate or above.
Smoking status, as defined in previous literature, was classified as never smoked (smoking fewer than 100 cigarettes), current smoker or former smoker (quitting after smoking more than 100 cigarettes). Physical activity was classified as sedentary, moderate (at least 10 minutes of exercise in the past 30 days that resulted in only slight sweating or a mild-to-moderate increase in breathing or heart rate) or vigorous (at least 10 minutes of exercise in the past 30 days that resulted in heavy sweating or an increase in breathing or heart rate). Previous medical conditions (including hypertension, diabetes, stroke and coronary heart disease) were determined based on questions regarding whether a doctor had been informed of the condition in the past. Body mass index was calculated using a standardised technique based on weight and height. Noise exposure included exposure to gun noise outside the workplace, noise outside the workplace, working in a noisy environment and exposure to loud noise at work.
For statistical analysis, categorical variables were expressed as proportions (percentages) and continuous variables were expressed as the mean (standard deviation) or median (interquartile distance). To compare the differences between groups, one-way ANOVA (normal distribution), the Kruskal–Wallis test (skewed distribution) and the chi-square test (categorical variables) were performed. After adjusting for all covariates, linear regression was used to describe the relationship between the Healthy Eating Index and hearing.
Logistic regression models were used to determine the odds ratios and 95 per cent confidence intervals (CIs) between the Healthy Eating Index and hearing loss. Model 1 was adjusted for sociodemographic characteristics, including age, sex, race, marital status, household income and educational level. Model 2 was adjusted for sociodemographic characteristics, smoking status, alcohol consumption, physical activity and BMI. Model 3 was comprehensively adjusted for sociodemographic characteristics, smoking status, alcohol consumption, physical activity, BMI, cardiovascular disease (CVD), hypertension, diabetes mellitus (DM) and noise exposure.
Furthermore, potential changes in the relationship between the Healthy Eating Index and hearing loss were assessed, including for the following variables: age (20–65 years vs >65 years), sex, marital status (married vs never married, living with a partner, other, i.e. widowed, divorced or separated individuals) and BMI (<25, 25–30, ≥30 kg/m2). Multivariate logistic regression was used to assess the heterogeneity among the subgroups, and the interaction between the subgroups and the Healthy Eating Index was examined using the likelihood ratio test.
All analyses were performed using the statistical package R 4.3.1 (R Foundation, Shanghai, China; http://www.R-project.org) and Free Statistics software version 1.9. Descriptive statistics were calculated for all participants. In the bilateral test, statistical significance was set at p less than 0.05.
Results
Study population
A total of 49 312 participants, all aged 20 years and older, completed interviews. We excluded those with missing data on the Healthy Eating Index 2015 (n = 8162), those with missing data on hearing loss (n = 32 422) and those with covariates (n = 3557). Ultimately, this cross-sectional study included 5171 participants from the National Health and Nutrition Examination Survey between 1999 and 2012, and 2015 and 2018. The detailed inclusion and exclusion processes are presented in Figure 1.
Baseline characteristics
Table 1 illustrates the baseline characteristics of all participants according to the Healthy Eating Index 2015. We included a total of 5171 patients with a mean age of 50.9 ± 18.5 years, of whom 60.9 per cent were non-Hispanic Whites and 52.9 per cent were men. Hearing loss was defined according to speech frequency PTA in the better-hearing ear, with more than > 25 dB HL and 20 dB HL or more as having hearing loss. The overall prevalence rates of hearing loss in the study population were 25.0 and 37.6 per cent, respectively.
Population characteristics by categories of the Healthy Eating Index 2015
SD = standard deviation; IQR = interquartile range.
The group with higher Healthy Eating Index scores was observed to have a higher proportion of men, non-Hispanic Whites, married individuals, higher family poverty income ratio, higher educational level, more never smokers, more mild alcohol users, lower BMI, greater physical activity, lower incidence of stroke and history of cardiovascular disease, no hypertension, no diabetes, no noise and normal hearing.
Relationship between Healthy Eating Index 2015 scores and hearing loss
Univariate analysis demonstrated that age, sex, race, marital status, family income, educational level, smoking status, alcohol consumption, physical activity, BMI, coronary heart disease, hypertension, DM and noise exposure were associated with low-frequency hearing loss, speech-frequency hearing loss and high-frequency hearing loss (see Tables S1, S2 and S3, respectively).
In linear multifactor analysis (Table 2), after adjusting for potentially confounding factors, there was a significant negative association between the Healthy Eating Index 2015 and low-frequency hearing, with a coefficient of −0.03 (95 per cent CI = −0.05 to −0.01, p = 0.001), speech-frequency hearing, with a coefficient of −0.04 (95 per cent CI = −0.06 to −0.01, p = 0.003), and high-frequency hearing, with a coefficient of −0.05 (95 per cent CI = −0.08 to −0.02, p = 0.003).
Association between Healthy Eating Index 2015 scores and hearing loss
When the Healthy Eating Index 2015 was a continuous variable, after adjusting for potential confounders, there was a significant negative association between the Healthy Eating Index 2015 and low-frequency hearing loss (Table 3), with odds ratio values of 0.99 (95 per cent CI = 0.98−0.99, p < 0.001) and 0.98 (95 per cent CI = 0.98−0.99, p < 0.001). The odds ratio was 0.99 in speech-frequency hearing loss, defined as hearing loss greater than 25 dB (95 per cent CI = 0.98−1, p = 0.008), and was 0.99 (95 per cent CI = 0.98−1, p = 0.006) in high-frequency hearing loss, defined as hearing loss greater than or equal to 20 dB.
Association between Healthy Eating Index 2015 scores and hearing loss
Model 1 was adjusted for sociodemographic variables (age, sex, race, marital status, PIR, education). Model 2 was adjusted for sociodemographic variables (age, sex, race, marital status, PIR, education), smoking status, alcohol intake, physical activity and body mass index. Model 3 was adjusted for sociodemographic variables (age, sex, race, marital status, PIR, education), smoking status, alcohol intake, physical activity, body mass index, CVD, hypertension, DM, noise. CI, confidence interval.
When the Healthy Eating Index 2015 was analysed using quintiles (see Table S4), a significant negative association was found between the Healthy Eating Index 2015 and hearing loss after adjusting for potential confounders. The adjusted odds ratio values of Healthy Eating Index 2015 scores and F scores (0–59), D(60–69), C(70–79), B(80–89) and A(90−100) for hearing loss are shown in Table S4. With hearing less than 20 dB as the normal value, the odds ratio value of low-frequency hearing in B(80–89) was 0.54 (95 per cent CI = 0.34−0.88, p = 0.013). The odds ratio values of speech-frequency band listening were 0.7 (95 per cent CI = 0.53−0.93, p = 0.013) in C(70–79) and 0.14 (95 per cent CI = 0.03−0.56, p = 0.005) in A(90−100). The odds ratio values for high-frequency hearing were 0.76 (95 per cent CI = 0.61−0.96, p = 0.02) in D(60–69) and 0.66 (95 per cent CI = 0.47−0.91, p = 0.012) in C(70–79). The odds ratio value in B(80–89) was 0.52 (95 per cent CI = 0.3–0.91, p = 0.021). However, when hearing was less than or equal to 25 dB, the odds ratio values of low-frequency hearing were 0.7 (95 per cent CI = 0.51–0.96, p = 0.029) in C(70–79) and 0.54 (95 per cent CI = 0.3–0.96, p = 0.035) in B(80–89).
Stratified analyses based on additional variables
Stratified analysis was performed on several subgroups to assess the potential impact of the relationship between the Healthy Eating Index 2015 and hearing loss. When stratified by sex, age, BMI and marital status, no significant interactions were observed between the subgroups. Given the sample size, a p value of less than 0.05 for marriage and BMI may not be statistically significant (see Figures S1, S2 and S3).
Discussion
We found that Healthy Eating Index scores are associated with hearing loss, and subgroup analyses showed stable results.
Spankovich’s findings support the link between healthier diets and lower high-frequency thresholds in adults.Reference Spankovich and Le Prell24 Adherence to healthy eating patterns has been linked to a reduced risk of hearing loss in women.Reference Curhan, Wang, Eavey, Stampfer and Curhan25 An Australian cross-sectional study found that overall diet quality was associated with concurrent vision and hearing loss.Reference Gopinath, Schneider, Flood, McMahon, Burlutsky and Leeder26 Previous studies have linked a healthy diet to hearing loss, which is similar to our findings.
Some studies have suggested that dietary supplement use is positively associated with hearing improvement at all frequencies.Reference Kang, Choi, Kim and Choi27 Studies by Rosenhall et al. have shown that eating fish is beneficial for hearing, while eating ‘junk food’ rich in low-molecular-weight carbohydrates is detrimental.Reference Rosenhall, Idrizbegovic, Hederstierna and Rothenberg28 A diet high in saturated fat, cholesterol and carbohydrates is a risk factor for hearing loss, and, conversely, increasing the intake of antioxidants in the form of protein, zinc, magnesium, selenium, iron, iodine, fruits, vegetables, polyunsaturated fatty acids (omega-3) and vitamins A, C, and E can prevent hearing loss from developing.Reference Rodrigo, Campos-Asensio, MÁ, Crespo and Olmedillas8, Reference Kim, Sim, Kim and Choi29–Reference Jung, Kim and Yeo31
Choi et al. believe that a high intake of seeds, nuts, fruits, seaweed and vitamin A has protective effects on hearing, and dietary antioxidants or anti-inflammatory foods may help reduce the occurrence of hearing loss.Reference Choi, Ahn and Moon32 Wei believes that the dietary intake of Mg and Ca is associated with a lower risk of hearing loss.Reference Wei33 Many scholars have studied the relationship between diet and hearing loss; some diets are protective factors, whereas others are risk factors.
Most previous studies on diet and hearing have focused on the analysis of single nutrients, with the limitation that nutrient intake is correlated, making it difficult to isolate the effects of one nutrient from those of others. Single-nutrient analyses, which do not consider biochemical interactions between nutrients, also increase the possibility of false-positive associations.Reference Dawes, Cruickshanks, Marsden, Moore and Munro34 As a supplement to single-nutrient analysis, dietary pattern analysis can better capture the synergistic and cumulative effects of total dietary intake on health outcomes.Reference Shelley35
The Healthy Eating Index assesses whether a group of foods meets the Dietary Guidelines for U.S. The index can be applied to any group of foods by assigning a score to each component and comparing its density to the relevant criteria. It has been widely used in numerous studies on diet quality in populations, the relationship between diet quality and health outcomes, the impact of interventions on diet quality, and economic and food-context-based studies.Reference Krebs-Smith, Pannucci, Subar, Kirkpatrick, Lerman and Tooze13
The Healthy Eating Index includes eating more fruits, vegetables, legumes, whole grains, nuts, dairy products, seafood, plant proteins and fatty acids, and less saturated fat, sugar and sodium. There are many mechanisms by which this healthy eating pattern prevents hearing loss, including the prevention of microvascular and macrovascular damage to cochlear blood flow, inhibition of oxidative damage and reduction of inflammation.Reference Curhan, Wang, Eavey, Stampfer and Curhan25 A lower high-fat diet in a high-quality diet may reduce induced oxidative stress, mitochondrial damage and apoptosis in the inner ear, which has a protective effect on inner-ear cells.Reference Tang, Hwang, Yang, Hsu, Wu and Liu36, Reference Le Prell, Gagnon, Bennett and Ohlemiller37 Inadequate blood supply to the cochlea can lead to hypoxia and ischaemic injury, oxidative stress, mitochondrial dysfunction, cellular damage, and peripheral and central auditory neurodegeneration.Reference Yamasoba, Lin, Someya, Kashio, Sakamoto and Kondo38
Dietary nutrients of polyunsaturated fatty acids and multivitamins, such as vitamin B12, vitamin C, calcium and selenium, may have antioxidant and neuroprotective effects.Reference El Soury, Fornasari, Carta, Zen, Haastert-Talini and Ronchi39 They may also protect against neurodegeneration of auditory nerve fibres and central auditory pathways.Reference Curhan, Wang, Eavey, Stampfer and Curhan25 Dietary guidance for patients with potential hearing loss is provided by examining the effects of a healthy diet index on hearing loss.
This study has several limitations. First, the cross-sectional design was a major limitation, and no causal relation can be inferred from this study. Second, the use of self-reported 24-hour food recall data is limited because this is prone to overestimation or underestimation. Finally, more participants were excluded because of the lack of data on any covariates that could have affected the results. Despite these limitations, our study has several strengths, a major one being the use of a large, nationally representative database to assess diet quality.
We found an association between Healthy Eating Index 2015 scores and hearing loss, therefore attention should be paid to the relationship between dietary quality and hearing loss. Future cohort studies or randomised controlled trials are needed to confirm this relationship.
• Hearing loss is a major global health burden linked to cognitive decline, depression and reduced quality of life, with modifiable risk factors understudied
• Prior studies suggest associations between single nutrients (e.g. vitamins, fatty acids) and hearing loss, but evidence on overall dietary patterns remains limited
• The Healthy Eating Index is a validated tool for assessing diet quality, but its relationship with hearing loss in adults is poorly characterised
• This was the first large-scale study demonstrating a significant inverse association between Healthy Eating Index 2015 scores and hearing loss across low-, speech-, and high-frequency thresholds in US adults
• Higher Healthy Eating Index 2015 scores (indicating better diet quality) correlate with reduced odds of hearing loss, particularly in quintile-based analyses (e.g. odds ratio = 0.52 for high-frequency hearing loss in the 80–89 score group)
• The study provide actionable evidence for integrating dietary guidelines into hearing loss prevention strategies, highlighting diet quality as a modifiable lifestyle factor and strengthens the rationale for future longitudinal studies to explore causal links between diet and auditory health.
Conclusions
We found that higher Healthy Eating Index scores were associated with better hearing, and that a healthy diet may also help to reduce the risk of hearing loss.
Supplementary material
The supplementary material for this article can be found at https://doi.org/10.1017/S0022215125000659.
Acknowledgments
The authors extend their gratitude to all National Health and Nutrition Examination Survey participants and staff members whose dedication made this study possible. Special thanks are extended to Dr Liu Huanxian from the Department of Neurology, Chinese PLA General Hospital, for his invaluable expertise in statistical methodology, consultation on study design rigor and critical review of the manuscript. This work was supported by the Zhejiang Provincial Traditional Chinese Medicine Science and Technology Project (2023ZF070).
Competing interests
None declared
