Working for Long Hours Is Associated With Dietary Fiber Insufficiency

Circadian Deregulation: Back Facing the Sun Toward Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) Development

Earth's rotation around its axis has pressured its inhabitants to adapt to 24 h cycles of day and night. Humans adapted their own circadian rhythms to the Earth's rhythms with a light-aligned awake-sleep cycle. As a consequence, metabolism undergoes drastic changes throughout the circadian cycle and needs plasticity to cope with opposing conditions in the day (when there is an increase in energy demands and food availability), and during the night (when prolonged fasting couples with cyclic changes in the energy demands across the sleep stages). In the last century, human behavior changed dramatically with a disregard for the natural circadian cycles. This misalignment in sleep and eating schedules strongly modulates the metabolism and energy homeostasis, favoring the development of obesity, metabolic syndrome, and metabolic dysfunction-associated steatotic liver disease (MASLD). This review summarizes the effects of circadian disruption, with a particular focus on the feeding and sleep cycles in the development of MASLD and hepatocellular carcinoma.

Association between long working hours and metabolic dysfunction-associated steatotic liver disease: a nationwide population-based study in Korea

OBJECTIVES

Long working hour is a known risk factor for metabolic diseases. We explored the association between working hours and metabolic dysfunction-associated steatotic liver disease (MASLD).

STUDY DESIGN

Data on working hours among 22,818 workers (11,999 females) from the Korea National Health and Nutrition Examination Survey (2013-2021) were used for this study.

METHODS

MASLD was defined as a combination of hepatic steatosis combined with one or more of cardiometabolic risk factors (overweight/obesity, prediabetes/diabetes, raised blood pressure, hypertriglyceridemia, low high-density lipoprotein cholesterol). Hepatic steatosis was assessed using the hepatic steatosis index. Logistic regression was used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

The overall prevalence of MASLD was 30.4% in men and 18.1% in women. Among male workers, 20.2% worked ≥55 h/week, whereas among female workers, 10.1% worked ≥55 h/week. Compared with working 35-40 h/week, working ≥55 h/week was positively associated with overweight/obesity (OR: 1.21; 95% CI: 1.05-1.40), pre-diabetes mellitus (pre-DM)/DM (OR: 1.20; 95% CI: 1.04-1.38), raised blood pressure (OR: 1.17; 95% CI: 1.02-1.35), and presence of any cardiometabolic risk factors (OR: 1.56; 95% CI: 1.21-2.02). The adjusted OR (95% CI) of the association between working hours and MASLD was 1.27 (1.09-1.47) for ≥55 h/week compared with working 35-40 h/week in male workers. In female workers, long working hours were not clearly associated with cardiometabolic risk factors and MASLD.

CONCLUSION

Long working hours are positively associated with MASLD among Korean male workers. Policy interventions are needed to mitigate the adverse metabolic effects of prolonged working hours.

The impact of long working hours on daily sodium intake

Background

Long working hours are associated with an increased risk of cardiovascular disease, yet the underlying mechanism(s) remain unclear. The study examines how occupational factors like working hours, shift work, and employment status correlate with dietary choices and sodium intake, impacting hypertension risk.

Methods

This study used data from the Korea National Health and Nutrition Examination Survey conducted between 2013 and 2020. The dataset included 8,471 respondents, all of whom were wage workers aged 20 or older and reported working at least 36 hours per week. Individuals who have been previously diagnosed with or are currently diagnosed with hypertension, diabetes, or dyslipidemia were excluded. The average daily sodium intake was assessed via a 24-hour dietary recall method. Average weekly working hours were categorized into 3 groups: 36-40 hours, 41-52 hours, and over 52 hours. Multiple logistic regression models were used.

Results

Study findings revealed that 83.7% of participants exceeded the recommended daily sodium intake of 2 g set by the World Health Organization. After adjusting for confounding factors, a positive correlation was observed between average working hours and daily sodium intake. Among males, statistical significance was found in the group with average weekly working hours of 41-52 hours (prevalence ratio [PR]: 1.17; 95% confidence interval [CI]: 1.05-1.30) and the group exceeding 52 hours (PR: 1.22; 95% CI: 1.09-1.38) when comparing the fourth quartile of daily sodium intake to the combined quartiles of Q1, Q2, and Q3. Among females, no significance was noted.

Conclusions

Long working hours were associated with increased sodium intake, primarily among male workers. This connection is likely attributed to having less time for home-cooked meals, resulting in higher fast food consumption and dining out. A workplace intervention promoting healthy eating and reducing stress is essential to lower sodium consumption and mitigate hypertension risk.

Differences of nutritional intake habits and Dietary Inflammatory Index score between occupational classifications in the Korean working population

Background

Human nutrient intake is closely related to the conditions of their workplace.

Methods

This study used data from the Korean National Health and Nutritional Examination Survey (KNHANES) conducted between 2016 and 2020. The study population comprised individuals aged 19 to 65 years who were engaged in paid work, excluding soldiers (total = 12,201, male = 5,872, female = 6,329). The primary outcome of interest was the Dietary Inflammatory Index (DII) score, which was calculated using dietary intake data. Generalized linear models were used for statistical analyses.

Results

Pink-collar workers had higher DII scores, indicating a potentially higher inflammatory diet than white-collar workers (mean: 2.18 vs. 1.89, p < 0.001). Green and blue-collar workers displayed lower levels of dietary inflammation (green: 1.64 vs. 1.89, p = 0.019, blue: 1.79 vs. 1.89, p = 0.022). After adjusting for sex, age, income, education, and energy intake, the sole trend that persisted was the comparison between white-collar and pink-collar workers.

Conclusions

DII scores and dietary patterns differed among occupational groups and genders.

Association between long working hours and diet quality and patterns: A latent profile analysis of a nationally representative sample of Korean workers

BACKGROUND

Long working hours are associated with cardiovascular and metabolic diseases. This study investigated the relationship between the working hours and dietary qualities and patterns in Korean workers.

METHODS

Data from 24,523 workers were extracted from the Korea National Health and Nutrition Examination Survey, 2013-2021. The Korean Healthy Eating Index (KHEI), which ranges from 0 to 100, with a higher score indicating greater adherence to Korean dietary guidelines and superior dietary quality, was used for dietary assessment. We identified dietary patterns and classified workers using latent profile analysis. Logistic regressions were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Five distinct dietary patterns emerged: healthy diet (24.8%), low-vegetable diet (14.0%), average diet (7.8%), low-fruit diet (31.4%), and poor diet (22.0%). The mean KHEI score was 60.8, with the highest score observed in the healthy diet pattern (71.3) and the lowest, in the poor diet pattern (50.0). Compared with working 35-40 h/week, working ≥55 h/week was negatively associated with KHEI scores (β: -1.08; 95% CI: -1.67, -0.49). Those working ≥55 h/week were less likely to have a healthy diet pattern (OR: 0.81; 95% CI: 0.72, 0.91) and more likely to have a low-fruit diet (OR: 1.36; 95% CI: 1.20, 1.55) or poor diet pattern (OR: 1.23; 95% CI: 1.05, 1.43) compared with those working 35-40 h/week.

CONCLUSION

Long working hours are associated with undesirable dietary quality and patterns. Policy interventions aimed at enhancing dietary quality are needed to alleviate the health burdens associated with long working hours.

Association between Obstructive Sleep Apnea and Chronic Kidney Disease According to Sex, Long Working Hours: The Korean National Health and Nutrition Examination Survey (2019-2020)

This study aimed to investigate whether obstructive sleep apnea (OSA) is associated with an increased risk of chronic kidney disease (CKD) and to perform subgroup analysis by sex and working hours. This cross-sectional study was conducted on 8157 subjects who participated in the Korea National Health and Nutrition Examination Survey (KNHANES). The adults completed the STOP-BANG score to measure their risk of OSA, and blood and urine samples were collected to ascertain the severity of CKD based on the estimated glomerular filtration rate and urine albumin-to-creatinine ratio. Multivariate logistic regression was used for complex sample analysis. After fully adjusting for the confounding variables, the high-risk OSA group showed a significantly higher risk of developing albuminuria and CKD than the low-risk group, particularly among men. Odds ratio (OR) 1.72, 95% confidence interval (CI) 1.13-2.6 and (OR 1.67, 95% CI 1.14-2.45), respectively. Additionally, men who worked for 40 h/week showed a significant association between OSA, CKD, and albuminuria. This study supports the link between OSA and the risk of kidney disease, especially among men and those who work long hours. Screening and treating OSA may be a crucial strategy for preventing kidney disease, particularly in high-risk populations.

The association between long working hours and obstructive sleep apnea assessed by STOP-BANG score: a cross-sectional study

PURPOSE

The relationship between night-shift work and obstructive sleep apnea (OSA) is well known, but that between OSA and long working hours is still unknown. This study explores the association between long working hours and OSA.

METHODS

Using cross-sectional Korean National Health and Nutrition Examination Survey 2020 data, we made multiple logistic regression models to calculate odds ratios (ORs) between weekly working hours and STOP-BANG scores for OSA screening. Stratified regression models by night or rotating shift work were also made.

RESULTS

In an adjusted model of STOP-BANG high-risk versus low-risk groups, the OR in the group exceeding 40 h/wk was higher but not statistically significant, 1.19 [95% confidence interval (CI) 0.66-2.15] compared to the group working 40 h/wk (standard working hours) or less. In the group exceeding 52 h/wk, the OR was 2.03 with statistical significance (95% CI 1.08-3.80). In the stratification analysis of daytime and night-shift work, the daytime worker results were similar to those in the non-stratified model. The point estimation values of ORs in the night-shift workers were higher than in the daytime workers; however, we did not observe a statistical significance.

CONCLUSION

Long working hours can increase the risk of OSA assessed by STOP-BANG scores.

Long Working Hours and the Risk of Glucose Intolerance: A Cohort Study

Long working hours have negative effects on the health of workers. Several studies have reported the association between long working hours and both diabetes and prediabetes. Therefore, we aimed to examine the temporal relationship between long working hours and glucose intolerance. Our cohort study collected data from 25,803 healthy male participants at baseline. To evaluate the risk of incident glucose intolerance, we estimated the hazard ratios (HRs) and 95% confidence intervals (CIs) using the Cox proportional hazards regression analyses. During 77,605.0 person-years of follow-up, 6741 participants developed glucose intolerance. Multivariable-adjusted HRs (95% CI) for weekly working 41-52 and >52 h compared with working 35-40 h, were 1.28 (1.17-1.40) and 2.80 (2.54-3.09), respectively. In the dose-response analyses, long working hours had a nearly linear relationship with the development of glucose intolerance across most working hours per week. The association between long working hours and incident glucose intolerance was stronger in the younger-age subgroups than in the older-age subgroups (p for interaction <0.001). Our large-scale cohort study demonstrated that long working hours were associated with incident glucose intolerance, with a dose-response relationship.

The Association Between Long Working Hours of Parents and Dyslipidemia in Their Children

The purpose of our study is to examine the association between children's low-density lipoprotein cholesterol (LDL-C) levels and their parents' working hours. We used data from the 2010–2018 Korea National Health and Nutrition Examination Survey in which lipid profile samples of 3,799 children were eligible. Logistic regression analyses were used with an outcome variable of the dichotomous LDL-C group and an exposure variable of the father's and mother's working hours, respectively. In logistic regression models adjusted for age, sex, household income, education level of children and parents, and working hours of the parents, mothers' working hours more than 52 h per week were significantly associated with their children's dyslipidemia [OR 2.14, 95% confidence interval (CI) 1.33–3.47] compared to working 40 h or less, whereas fathers' working hours did not show statistical significance (OR 1.08, 95% CI 0.71–1.66) in the same manner. The association was greatest for elementary school students for mothers working more than 52 h per week (OR 3.42, 95% CI 1.64–7.14) compared to those working hours 40 h per week or less. Mothers' long working hours were associated with a higher prevalence of dyslipidemia in their children. The association was strongest for elementary school students. Proper working time of parents is required for their children's health.