Impacts of Digital Healthy Diet Literacy and Healthy Eating Behavior on Fear of COVID-19, Changes in Mental Health, and Health-Related Quality of Life among Front-Line Health Care Workers

Background: We aimed to examine the impacts of digital healthy diet literacy (DDL) and healthy eating behaviors (HES) on fear of COVID-19, changes in mental health, and health-related quality of life (HRQoL) among front-line healthcare workers (HCWs). Methods: An online survey was conducted at 15 hospitals and health centers from 6–19 April 2020. Data of 2299 front-line HCWs were analyzed—including socio-demographics, symptoms like COVID-19, health literacy, eHealth literacy, DDL, HES, fear of COVID-19, changes in mental health, and HRQoL. Regression models were used to examine the associations. Results: HCWs with higher scores of DDL and HES had lower scores of FCoV-19S (regression coefficient, B, −0.04; 95% confidence interval, 95% CI, −0.07, −0.02; p = 0.001; and B, −0.10; 95% CI, −0.15, −0.06; p < 0.001); had a higher likelihood of stable or better mental health status (odds ratio, OR, 1.02; 95% CI, 1.00, 1.05; p = 0.029; and OR, 1.04; 95% CI, 1.00, 1.07; p = 0.043); and HRQoL (OR, 1.02; 95% CI, 1.01, 1.03; p = 0.006; and OR, 1.04; 95% CI, 1.02, 1.06; p = 0.001), respectively. Conclusions: DDL and HES were found as independent predictors of fear of COVID−19, changes in mental health status, and HRQoL in front-line HCWs. Improving DDL and HES should be considered as a strategic approach for hospitals and healthcare systems.


Introduction
The burden of mental health problems among healthcare workers (HCWs) has been highlighted, especially in low and middle-income countries [1]. The high prevalence of psychological health problems in HCWs was reported in meta-analyses [2][3][4][5]. The problem has similarly been reported in Vietnam during the COVID-19 pandemic [6].
HCWs face social stigma, discrimination, raising concerns about their safety and family members' health [7][8][9]. Front-line HCWs are even at high risk of COVID-19 infection [10]. These affect their psychological health and well-being [7][8][9], especially when they do not feel protected [11]. Therefore, their fear reaction, changes in mental health, and healthrelated quality of life during the pandemic should be addressed. It suggests developing early evidence-based sustainable interventions to prevent and mitigate the short-and longterm effect of the COVID-19 pandemic on HCWs' mental health and well-being [12][13][14][15]. The improvement of psychological health and well-being could enhance the infection control practices among HCWs [16], which may further improve patient care quality [17]. Therefore, we must address the impact of facing COVID-19 in HCWs on their psychological health and well-being and identify the associated predictors which might further contain the pandemic.
The symptoms like COVID-19 negatively influenced on people's mental health and health-related quality of life (HRQOL) [18]. Digital healthy diet literacy (DDL) was linked with healthier eating behavior [19] which further modified the negative effect of COVID-19 on mental health [20]. In addition, health literacy, eHealth literacy (eHEALS), and DDL significantly modified the negative impact of COVID-19 on HRQOL [21].
The roles of DDL and healthy eating behaviors (HES) on mental health and quality of life have been investigated in patients and students [19,20]. However, the roles of DDL and HES have not been studied on HCWs. In addition, their role in fear was also remained to be explored. Therefore, we aimed to examine the associated predictors of fear of COVID-19, changes in mental health, and health-related quality of life (HRQoL) among front-line HCWs, in which impacts of DDL and HES were emphasized.

Study Design and Participants
A cross-sectional study was approved by the Ethical Review Committee of Hanoi University of Public Health, Vietnam (IRB no. 133/2020/YTCC-HD3). The informed consent was achieved from all participants before taking the survey.
An online survey was conducted from 6-19 April 2020 on HCWs who were working at 12 hospitals and three health centers across Vietnam [22]. We analyzed a sample of 2299 front-line HCWs (who were working at the outpatient department, emergency department, isolation areas, imaging and laboratory diagnosis department, patient administration areas), including 90  The first part of the questionnaire was to ask HCWs about their age, gender, marital status, ability to pay for medication, self-perceived social status, types of health care personnel (doctors, nurses, or others), and previous epidemic containment experiences (e.g., SARS, tuberculosis, influenza A). Body mass index (BMI, kg/m 2 ) was calculated by weight (kg)/height (m 2 ). In addition, comorbid conditions were assessed using the items of the Charlson comorbidity index [23,24].

Symptoms like COVID-19
The next part was to ask HCWs about the symptoms that were similar to COVID-19 symptoms (S-COVID-19-S) [25], including fever, cough, and dyspnea, myalgia, fatigue, sputum production, confusion, headache, sore throat, rhinorrhea, chest pain, hemoptysis, diarrhea, and nausea/vomiting. HCWs were classified as having S-COVID-19-S if they had any of those symptoms. The S-COVID-19-S showed the negative impact on mental health and HRQOL in previous studies [18,26].

Health Literacy and Digital Healthy Diet Literacy
Health literacy (HL) and digital healthy diet literacy (DDL) were assessed using a 12-item short-form health literacy questionnaire (HLS-SF12) [27,28], and four-item digital healthy diet literacy (DDL-4) [19]. These tools were validated and used in the Vietnamese context [19,21]. HCWs responded to each item on a four-point Likert scale from 1 (very difficult) to 4 (very easy). HL index and DDL index scores were standardized to a unified metric from 0 to 50, using formula (1), with a higher score indicating better HL [19,29] where Index is the specific index calculated, Mean is the mean of all participating items (12 items for HL index, 4 items for DDL index), 1 is the minimal possible mean (leading to a minimum index of 0), 3 is the range of the mean, and 50 is the chosen maximum index value.

eHealth Literacy Scale
HCWs' eHealth literacy was assessed using the eHealth literacy scale (eHEALS) with eight items [30] which was validated and used in Vietnam [21,22]. HCWs reported their experiences on a five-point Likert scale from 1 (strongly disagree) to 5 (strongly agree). The sum scores range from 8 to 40, with high scores indicating better eHEALS.

Healthy Eating Behavior
Healthy eating behavior was assessed using the 5-item healthy eating score (HES-5) [31,32]. The HES-5 utilization was comparable with the 2015 health eating index in assessing the overall diet quality [32] which was validated and used in Vietnam [20]. HCWs reported their eating/drinking frequency of fruits, vegetables, whole grains, dairy, and fish over the last 30 days on a five-point scale from 0 (rarely or never) to 1 (1-2 times/week), 2 (3-6 times/week), 3 (once/day), 4 (twice/day), and 5 (3 or more times/day). The total HES scores range from 0 to 25, the higher score the better healthy eating behavior.

Fear of COVID-19
The fear was assessed using the seven-item fear of COVID-19 scale (FCoV-19S) [33] which was used in Vietnam [21,34]. HCWs responded to each item on a five-point Likert scale from 1 (strongly disagree) to 5 (strongly agree). The sum score of seven items ranges from 7 to 35, with higher scores indicating greater fear.

Changes in Mental Health and Health-Related Quality of Life
Healthcare workers (HCWs), in fact, have better knowledge and ability to detect the changes in their mental health and HRQOL than the general public. Therefore, to assess the changes, HCWs were asked using the question "All in all, how could you say your mental health currently is, as compared with that before the pandemic?", and "All in all, how could you say your health-related quality of life (HRQoL) is, as compared with that before the pandemic?". The response options were (1) "worse", (2) "stable", or (3) "better". To facilitate the analysis, we classified the responses into two groups (worse vs. stable or better).

Data Collection Procedure
Investigators and research assistants (doctors, nurses, medical students) of each hospital sent to survey link to front-line HCWs via messenger or email. The contact information was available from human resource office of each hospital. HCWs had signed the online informed consent before took the survey. It took about 15-20 min to complete the survey. The mandatory fields were applied for all survey questions to eliminate the missing data. Data were coded and analyzed confidentially by researchers.

Data Analysis
Firstly, one-way ANOVA test and chi-square test were used appropriately to explore the distributions of FCoV-19S, changes in mental health, and HRQoL by different categories of independent variables. Secondly, bivariate and multivariate linear regression models and logistic regression models were used to examine the associated factors of FCoV-19S, changes in mental health, and HRQoL. To minimize residual effects of confounders, all the factors in the bivariate model were analyzed in the multivariate model [35]. To eliminate the multicollinearity in multivariate models, the correlations among independent variables were analyzed using Spearman correlation. Since the DDL moderately correlates with HL (rho = 0.68) and eHEALS (rho = 0.38; Table S1), DDL and other independent variables were analyzed in the multivariate models. Data were analyzed using the IBM SPSS Version 20.0 for Windows (IBM Corp, Armonk, NY, USA). The significance level was set at a p-value < 0.05.

Characteristics of Front-Line HCWs
In 2299 HCWs, 19.9% were aged 41-60, 33 * Health care workers were asked whether their mental health got worse, stable, or better during the pandemic as compared to that before the pandemic. ** Health care workers were asked whether their HRQoL got worse, stable, or better during the pandemic as compared to that before the pandemic. *** suspected coronavirus disease-2019 symptoms include fever, cough, dyspnea myalgia, fatigue, sputum production, confusion, headache, sore throat, rhinorrhea, chest pain, hemoptysis, diarrhea, and nausea/vomiting.

Discussion
Results of the current study highlight the associations of digital healthy diet literacy (DDL) and healthy eating behavior (HES) with fear of COVID-19 (FCoV-19S), changes in mental health, and health-related quality of life (HRQoL).
In the current study, higher scores of DDL and HES were associated with a higher likelihood of having stable or better mental health status and HRQoL during the pandemic. The link between eHEALS and DDL was also found in this study. They both showed the benefits on HRQOL during the pandemic as reported in a previous study [21]. In addition, DDL was linked with higher likelihood of healthier eating behavior in nursing and medical students [19]. In turn, healthy eating behavior showed a beneficial impact on depression in outpatients [20], on depression, and quality of life in college students [36]. Fruits and vegetables showed positive impacts on mental health in the adult population [37]. Moreover, healthy eating behavior was also associated with a higher score of well-being in HCWs [38]. Therefore, improving HCWs' DDL and providing healthy meals are the important responsibility of managers, policymakers which could significantly improve HCWs' mental health and HRQoL life amidst the pandemic. Improving DDL and HES should be added in the global actions to protect HCWs from negative effects of the COVID-19 pandemic [39].
Both DDL and HES were associated with lower FCoV-19S scores in HCWs in the current study. This finding is in light of previous evidence that people with higher health literacy had lower fear scores [34]. Healthy dietary habits were associated with lower depression states in college students [36]. In addition, healthy food habits were also linked to better psychological health during the pandemic [40]. HCWs are not immune to fear and may suffer from a higher rate of fear than others, especially front-line HCWs. Therefore, courage is a decision to enhance DDL, and HES, and in turn, reduce fear, and adhere to infection prevention practices to provide a higher quality of care [41].
Besides, as compared to HCWs with no previous epidemic containment experience, those with the experiences had a higher likelihood of stable or better mental health status and HRQoL. In addition, doctors had lower FCoV-19S scores. This could be explained that experienced HCWs have a better ability to regulate their negative emotions, and maintain their quality of life. In addition, male HCWs had lower FCoV-19S scores but worse HRQoL during the pandemic. A previous study has reported that female HCWs are more vulnerable to mental health problems than males [42]. Male HCWs reported a lower fear of COVID-19 than females [43].
In addition, front-line HCWs with ever married status had a higher FCoV-19S score. This could be linked with HCWs' concerns about their own and family members' safety and health which made them feel a greater fear of COVID-19 [7,8].
Lastly, HCWs aged 41-60 years, or those with better ability to pay for medication had a higher likelihood of stable or better HRQoL during the pandemic. This could be explained that HCWs at the age of 41-60 years usually had a better financial status which may help to facilitate their life better and keep quality of life stable during the pandemic. The older age was also found to be associated with better well-being in HCWs in a previous study [38].
Our study has some limitations. First, the reporting bias might happen in measuring the changes in mental health and HRQoL states. However, the studied population is HCWs which could minimize the bias. Second, COVID-19 infection may influence the results as we cannot identify the positive COVID-19 cases. The results can be guaranteed as no new confirmed case in HCWs during the survey time [44]. Third, the causal relationship cannot be drawn from a cross-sectional design. Despite the mentioned drawbacks, the findings could help to suggest potential research directions and interventions that improve HCWs' mental health and quality of life.

Conclusions
Digital healthy diet literacy (DDL) and healthy eating behaviors (HES) were found as independent predictors of fear of COVID-19, changes in mental health status, and health-related quality of life (HRQoL) in front-line healthcare workers (HCWs). A strategic approach to improve DDL and HES is highly suggested to protect HCWs' psychological health and quality of life during the pandemic, especially for front-line HCWs.
Supplementary Materials: The following are available online at https://www.mdpi.com/article/10 .3390/nu13082656/s1, Table S1: Spearman correlations (rho) of independent variables (n = 2299).  Informed Consent Statement: The online informed consent was obtained from all subjects involved in the study.
Data Availability Statement: Data will be available on the reasonable request from the corresponding author.