Abstract
Background and aims
The pathogenic mechanism of sedentary behavior involves chronic inflammation, which can be affected by dietary inflammation. This study aimed to determine the association between dietary inflammation, sedentary behavior, and risk of death.
Methods
Data from the National Health and Nutrition Examination Survey (2007–2018) were analyzed. Sedentary behavior was evaluated using self-reported sitting hours in a day, and dietary inflammation was assessed using dietary inflammatory index (DII). Deaths were ascertained through the National Death Index until December 31, 2019. The interaction between dietary inflammation and sedentary behavior was evaluated through multivariable Cox regression analysis.
Results
18,425 participants (mean age: 48.2 years; female proportion, 51.7%) were involved for analysis. During a median follow-up of 7.7 years, we confirmed 1,960 all-cause and 488 cardiovascular deaths. After adjustment for confounders, both pro-inflammatory diets and sitting for 6 h/d or more were risk factors for all-cause and cardiovascular deaths (P < 0.05). Of note, we found that dietary inflammation modified the association between sitting time and the risk of all-cause deaths (P for interaction = 0.03). Compared with shorter sitting time (< 6 h/d), prolonged sitting time (≥ 6 h/d) was correlated with an elevated risk of all-cause deaths among participants with pro-inflammatory diets (DII ≥ 0) (HR: 1.50, 95%CI: 1.35–1.66, P < 0.001), but not among participants with anti-inflammatory diets (DII < 0) (HR: 1.20, 95%CI: 0.98–1.46, P = 0.08).
Conclusions
Dietary inflammation modified the association between sedentary behavior and the risk of all-cause deaths. Anti-inflammatory diets might mitigate the detrimental effects of sedentary behavior on survival in US adults.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12986-025-00907-2.
Keywords: Modification, Dietary inflammatory index, Sedentary behavior, Deaths, NHANES
Introduction
Sedentary lifestyles are highly prevalent worldwide. On average, a US adult spends more than half of his/her waking time (approximately 7.7 h per day) sedentary [1]. Prior observational studies have shown that sedentary behaviors were independently correlated with increased risks of chronic diseases [2, 3], and death [4], regardless of physical activity levels. As for the mechanisms responsible, it was widely accepted that inflammatory processes, as well as antioxidant/oxidant homeostasis, were the main pathogenic processes [5].
Diet is a main influencing factor of health [6]. In 2021, it was estimated that 178 million disability-adjusted life years and 7 million deaths could be attributed to poor diet worldwide [7]. Studies have reported the benefits of anti-inflammation diets in reducing the risk of death among the general population [8]. According to a previous meta-analysis, the extent of dietary inflammation was correlated with linearly incremental risks of all-cause and cardiovascular disease (CVD) deaths [9]. Indeed, diet has been shown to affect chronic inflammation by modulating levels of inflammatory markers (i.e., cytokines, cytokine receptors, acute-phase proteins, and soluble adhesion molecules), as well as glucose and lipid metabolism [10, 11]. Considering this information, anti-inflammatory diets might mitigate the negative effects of sedentary behavior.
However, few studies have investigated the effect of dietary inflammation on the association between sedentary behavior and the risk of death. Indeed, sedentary behavior has been recognized as the fourth greatest risk factor for deaths worldwide, which accounted for almost 6% of global deaths [12]. Considering the prevalence and hazards of sedentary behavior, investigating whether dietary inflammation modified the correlation between sedentary behavior and risk of death had an important public health implication. Hence, we analyzed data from the National Health and Nutrition Examination Survey (NHANES) to investigate the relationship between sedentary behavior and risks of all-cause and CVD deaths among the US population consuming pro- or anti-inflammatory diets.
Materials and methods
Study population
Data analyzed in our study were collected from NHANES, a multistage stratified sampling survey conducted to evaluate the health and nutritional status of the civilian US population. Before this survey, the protocols for NHANES were approved by the National Center for Health Statistics and Ethics Review Board, and informed written consent was obtained at enrollment from all the participants.
We used data collected from 6 cycles (2007–2018) of NHANES. Among the 59,842 participants in NHANES between 2007 and 2018, we excluded individuals aged < 20 years old, pregnant, and those with incomplete information for dietary inflammatory index (DII), sitting time, death, or covariates. After excluding the above, 18,425 eligible individuals were selected for final analysis (Fig. 1).
Fig. 1.
Study cohort. Abbreviation: DII, dietary inflammation index
Assessment of sitting time and DII
Sitting time, defined as time spent sitting at home, at school, getting to and from places, or with friends on a typical day, was evaluated by the Physical Activity Questionnaire in NHANES. Following recent literature [13], sitting time was classified by predefined thresholds: < 6 h and ≥ 6 h per day (h/d). Details of the dietary inflammatory index (DII), a tool frequently used in assessing the dietary inflammatory potential, have been previously reported [14]. In our study, 27 dietary nutrients associated with inflammatory potential were selected for the computation of DII, including carbohydrates, protein, fiber, total fat, saturated fat, cholesterol, polyunsaturated fatty acid, monounsaturated fatty acid, n-6 fatty acid, n-3 fatty acid, iron, zinc, selenium, manganese, alcohol, caffeine, folic acid, β-carotene, niacin, thiamin, riboflavin, vitamins A/B6/B12/C/D/E. Participants were divided into anti-inflammatory diets (DII < 0) or pro-inflammatory diets (DII ≥ 0) groups.
Ascertainment of deaths
We identified deaths via the National Death Index search up to December 31, 2019. Moreover, the causes of death were obtained by referring to the International Classification of Diseases (ICD), tenth revision. CVD deaths were defined as deaths due to cerebrovascular (ICD codes: I60-I69) or cardiac diseases (ICD codes: I00-I09, I11, I13, or I20-I51).
Assessment of covariates
Covariates comprised socio-demographic factors, lifestyle behaviors, and medical history. Socio-demographic factors, such as age, sex, race, education level, and family income-poverty ratio (PIR), were ascertained by interview in person. Anthropometric measurements (weight, height, and waist circumference [WC]) were performed by the staff members using standardized procedures. Body mass index (BMI) was calculated by body weight (kg)/height (m)2. For education level, individuals were classified into below high school, high school, and beyond. For smoking, individuals were grouped as never, former, or current smokers. For alcohol use, individuals were classified into heavy drinkers (consuming alcohol ≥ 10 drinks per month), light-to-moderate drinkers (1–10 drinks per month), or non-drinkers. Physical activity (PA) level was computed as the weekly minutes spent in moderate-intensity physical activity plus twice the weekly minutes of vigorous-intensity physical activity. PA level was defined as active if the total amount of PA was greater than or equal to 150 min/week [15]. The neutrophil/lymphocyte ratio (NLR) and systemic inflammation response index (SIRI), have been considered reliable indicators for systemic inflammation [16]. NLR was calculated by dividing neutrophil count by lymphocyte count, and SIRI was calculated as NLR multiplied by monocyte count (109/L). Diabetes was determined through laboratory results including fasting glucose, 2 h plasma glucose, and glycated hemoglobin or the self-reported presence of diabetes. Chronic kidney disease (CKD) was considered when estimated glomerular filtration rate was less than 60 mL/min/1.73m2. Hypercholesterolemia was determined through total cholesterol ≥ 240 mg/dL or the self-reported presence of hypercholesterolemia. Hypertension was determined through blood pressure ≥ 140/90 mmHg or the self-reported presence of hypertension. The use of antihypertensive, lipid-lowering, and antidiabetic medication was identified using questionnaire data and examiner documentation of prescription medications presented during personal interviews. CVD history was determined through the self-reported presence of coronary heart disease, angina pectoris, myocardial infarction, heart failure, or stroke.
Statistical analysis
We used mean and standard error to present continuous variables and compared them by analysis of variance. Categorical variables were presented by numbers (weighted percentages) and compared by χ2 tests. Survey weights were considered to ensure data were nationally representative. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated with Cox regression models. Three models were constructed. Model 1 adjusted for age. Model 2 adjusted for Model 1 confounders plus sex, race, WC, education level, family PIR, smoking status, alcohol use, and PA. Model 3 adjusted for model 2 confounders plus the history of diabetes, CKD, hypertension, hypercholesterolemia, use of antihypertensive, lipid-lowering, and antidiabetic medication, CVD, and cancer. A stepwise selection process was applied, with all variables significant (p < 0.05) in univariable analysis retained in the initial multivariable model, followed by backward elimination. Colinearity among independent variables was assessed by examining variance inflation factors, and no evidence of colinearity was found. Restricted cubic splines (RCS) analysis with 3 knots was performed to explore dose-response association. To examine whether dietary inflammation modified the correlation between sedentary behavior and risk of death, we further stratified data according to pro- or anti-inflammatory dietary groups. Multiplicative and additive interaction terms between sitting time and DII were also included to test effect modification. To address the concern on reverse causality, sensitivity analyses were performed by excluding participants with follow-up of less than three years. Subgroup analyses were also conducted to test the association between sedentary behavior and risk of death according to pro- or anti-inflammatory dietary groups in participants of different ages (< or ≥ 65 years) or genders.
The following R packages were used: the “survey” package was used to perform complex survey analyses; the “car” package was used to check the collinearity between variables; the “survival” and “rms” packages were used to examine the association of DII or sitting time with the risk of death; the “interactionR” package was used to calculate the additive and multiplicative interactions. Analyses were conducted through R and associated packages (version 4.3.1), and two-sided P values less than 0.05 were considered statistically significant.
Results
Participant characteristics
We included a total of 18,425 participants (weighted average age, 48.2 years; weighted female proportion, 51.7%). The mean sitting time was 6.3 h/d, and the mean DII was 0.95. Baseline characteristics for participants stratified by DII and daily sitting time were summarized in Table 1. 54.0% spent 6 h or more sitting in a day, and 70.6% had pro-inflammatory diets. Whether participants consumed anti-inflammatory or pro-inflammatory diets, those who sat for 6 or more hours per day were more likely to be non-Hispanic whites or other races, inactive, more educated, have higher BMI, WC, and PIR, smoke less, drink more, prevalent diabetes, hypertension, hypercholesterolemia, and medication use compared to those who sat for less than 6 h per day.
Table 1.
Baseline characteristics of different groups stratified by DII and daily sitting time
| Characteristic | Total | Anti-inflammatory diets (DII < 0) | P value* | Pro-inflammatory diets (DII ≥ 0) | P value** | ||
|---|---|---|---|---|---|---|---|
| Sitting time < 6 h/d | Sitting time ≥ 6 h/d | Sitting time < 6 h/d | Sitting time ≥ 6 h/d | ||||
| Participants | 18,425 | 2281 | 2484 | 6896 | 6764 | ||
| Age years | 48.23 (0.29) | 48.30 (0.47) | 49.36 (0.48) | 0.07 | 47.11 (0.34) | 48.70 (0.32) | 0.001 |
| Female, n (%) | 9420 (51.7) | 887 (42.2) | 898 (35.3) | 0.001 | 3815 (57.6) | 3820 (57.0) | 0.62 |
| BMI, kg/m2 | 29.04 (0.09) | 27.39 (0.17) | 28.40 (0.18) | < 0.001 | 28.70 (0.11) | 30.19 (0.12) | < 0.001 |
| WC, cm | 99.33 (0.23) | 95.61 (0.46) | 99.00 (0.45) | < 0.001 | 97.99 | 107.94 | < 0.001 |
| Race, n (%) | < 0.001 | < 0.001 | |||||
| Mexican American | 2658 (7.8) | 462 (10.7) | 230 (4.5) | 1326 (11.2) | 640 (5.1) | ||
| Other Hispanic | 1833 (5.0) | 237 (5.7) | 188 (3.6) | 883 (6.9) | 525 (3.7) | ||
| Non-Hispanic White | 8579 (70.6) | 1051 (70.7) | 1334 (77.8) | 2806 (64.4) | 3388 (72.9) | ||
| Non-Hispanic Black | 3646 (10.0) | 306 (6.0) | 363 (6.0) | 1429 (11.8) | 1548 (11.7) | ||
| Other Race | 1709 (6.6) | 225 (6.9) | 369 (8.2) | 452 (5.7) | 663 (6.6) | ||
| Education level, n (%) | < 0.001 | < 0.001 | |||||
| Below high school | 4144 (14.7) | 471 (12.7) | 225 (5.4) | 2185 (21.8) | 1263 (13.1) | ||
| High school | 4207 (22.2) | 466 (19.5) | 382 (14.2) | 1804 (27.2) | 1555 (22.3) | ||
| Beyond high school | 10,074 (63.1) | 1344 (67.9) | 1877 (80.5) | 2907 (51.0) | 3946 (64.6) | ||
| Family, PIR | 3.03 (0.05) | 3.18 (0.06) | 3.70 (0.04) | < 0.001 | 2.62 (0.04) | 3.05 (0.05) | < 0.001 |
| Smoking status, n (%) | 0.01 | 0.05 | |||||
| Never | 10,119 (54.8) | 1305 (58.6) | 1469 (59.1) | 3749 (53.3) | 3596 (53.0) | ||
| Former | 4662 (25.9) | 638 (27.9) | 736 (31.5) | 1572 (22.8) | 1716 (25.4) | ||
| Current | 3644 (19.3) | 338 (13.5) | 279 (9.4) | 1575 (23.8) | 1452 (21.5) | ||
| Alcohol use, n (%) | 0.02 | 0.01 | |||||
| Never | 5045 (22.0) | 535 (19.9) | 504 (16.0) | 2153 (25.6) | 1853 (22.3) | ||
| Light-to-moderate | 10,721 (59.6) | 1341 (59.4) | 1468 (58.3) | 3899 (58.2) | 4013 (61.6) | ||
| Heavy | 2659 (18.3) | 405 (20.7) | 512 (25.7) | 844 (16.2) | 898 (16.1) | ||
| NLR | 2.20 (0.02) | 2.13 (0.03) | 2.20 (0.03) | 0.08 | 2.18 (0.02) | 2.25 (0.02) | 0.01 |
| SIRI, ×109 | 1.26 (0.01) | 1.17 (0.02) | 1.27 (0.03) | 0.001 | 1.22 (0.02) | 1.32 (0.02) | < 0.001 |
| Active physical activity, n (%) | 5024 (31.9) | 938 (47.2) | 691 (32.9) | < 0.001 | 2138 (36.4) | 1257 (22.2) | < 0.001 |
| Diabetes, n (%) | 3422 (14.1) | 304 (9.4) | 400 (12.3) | 0.01 | 1320 (13.6) | 1418 (16.8) | < 0.001 |
| CKD, n (%) | 3102 (14.1) | 273 (10.4) | 350 (10.6) | 0.85 | 1061 (13.2) | 1418 (17.6) | < 0.001 |
| Hypertension, n (%) | 7830 (37.6) | 840 (32.2) | 1015 (36.5) | 0.03 | 2869 (36.9) | 3106 (40.6) | 0.002 |
| Hypercholesterolemia, n (%) | 7596 (41.0) | 914 (39.2) | 1051 (45.1) | 0.002 | 2764 (38.6) | 2867 (41.8) | 0.01 |
| Antidiabetic medication, n (%) | 2141 (8.7) | 181 (5.7) | 248 (7.6) | 0.02 | 810 (8.3) | 902 (10.6) | 0.001 |
| Antihypertensive medication, n (%) | 6133 (28.8) | 621 (22.9) | 821 (28.1) | 0.003 | 2097 (26.2) | 2594 (33.3) | < 0.001 |
| Lipid-lowering medication, n (%) | 3739 (18.6) | 373 (15.0) | 530 (20.3) | 0.001 | 1319 (16.7) | 1517 (21.7) | < 0.001 |
| CVD, n (%) | 2024 (8.7) | 158 (5.8) | 246 (7.8) | 0.05 | 686 (7.8) | 934 (10.8) | < 0.001 |
| Cancer, n (%) | 1863 (10.7) | 225 (10.3) | 305 (12.4) | 0.09 | 589 (9.3) | 744 (11.4) | 0.01 |
Continuous variables were presented as the mean and standard error, and category variables were described as the unweighted number and weighted percentage. All estimates accounted for complex survey designs. *P value referred to the comparison between groups (sitting time < 6 h/d versus ≥ 6 h/d) in participants with DII < 0. **P value referred to the comparison between groups (sitting time < 6 h/d versus ≥ 6 h/d) in participants with DII ≥ 0. Abbreviation: BMI, body mass index; WC, waist circumference; NLR, neutrophil/lymphocyte ratio; SIRI, systemic inflammation response index; CKD, chronic kidney disease; CVD, cardiovascular disease; DII, dietary inflammation index; PIR, income-to-poverty ratio
Relationship between sitting time, DII, and risks of deaths
During a median follow-up of 7.7 years (maximum follow-up, 13.3 years), 1,960 deaths occurred, of which 488 were due to cardiovascular disease. After adjusting for age, sex, race, WC, education level, family PIR, smoking status, alcohol use, PA, history of diabetes, CKD, hypertension, hypercholesterolemia, use of antihypertensive, lipid-lowering, and antidiabetic medication, CVD, and cancer, participants sitting for more than 6 h/d had higher risks of all-cause (HR: 1.42, 95%CI: 1.29–1.56, P < 0.001) and CVD deaths (HR: 1.41, 95%CI: 1.17–1.70, P < 0.001) than those sitting for less than 6 h/d. Meanwhile, compared with anti-inflammatory diets, pro-inflammatory diets were correlated with increased risks of all-cause (HR: 1.15, 95%CI: 1.03–1.29, P = 0.01) and CVD deaths (HR: 1.37, 95%CI: 1.08–1.75, P = 0.01) (Table S1). The RCS curve indicated that both sitting time and DII were linearly positively correlated with risks of all-cause and CVD deaths (P for non-linearity > 0.05) (Figure S1).
In joint analyses, individuals with pro-inflammatory diets and sitting time of 6 h/d or more had increased risks of all-cause (HR: 1.52, 95%CI: 1.29–1.79, P < 0.001) and CVD deaths (HR: 1.79, 95%CI: 1.25–2.57, P = 0.001) than those with anti-inflammatory diets and sitting time of less than 6 h/d (Table S2).
Interaction between dietary inflammation and sedentary behavior
Further analyses indicated a significant interaction between dietary inflammation and sitting time about the risk of all-cause deaths on both additive (P for additive interaction: 0.002) and multiplicative scales (P for multiplicative interaction: 0.03). The relative excess risk due to interaction (RERI) was 0.32 (95%CI: 0.10–0.55), suggesting the joint effect of pro-inflammatory diets and sitting time ≥ 6 h/d exceeded the sum of two individual effects on all-cause deaths (Table S3). Of note, after multivariate adjustment, the relationship between prolonged sitting time (≥ 6 h/d) and increased risk of all-cause deaths was only observed among participants who consumed pro-inflammatory diets (HR: 1.50, 95%CI: 1.35–1.66, P < 0.001), but not in participants who consumed anti-inflammatory diets (HR: 1.20, 95%CI: 0.98–1.46, P = 0.08) (Table 2; Fig. 2). In addition, the relationship between prolonged sitting time (≥ 6 h/d) and the risk of CVD deaths also seemed to be stronger among participants who consumed pro-inflammatory diets (HR: 1.48, 95%CI: 1.20–1.82, P < 0.001), compared with participants who consumed anti-inflammatory diets (HR: 1.21, 95%CI: 0.78–1.89, P = 0.39), although the interaction for the risk of CVD deaths was not significant (P for multiplicative interaction: 0.34). Moreover, no additive interaction effect was found between sitting time and dietary inflammation on the risk of CVD deaths (P for additive interaction: 0.05). Sensitivity analyses, after excluding individuals who had less than 3-year follow-up, showed similar results (Table S4-S7 and Figure S2).
Table 2.
Association of sitting time with all-cause and CVD deaths stratified by DII
| Death/No. | Weighted death (%) | Hazard ratio (95% CI) | ||||
|---|---|---|---|---|---|---|
| Model 1 | Model 2 | Model 3 | ||||
| All-cause Deaths | ||||||
| Anti-inflammatory diets (DII < 0) | Sitting time < 6 h/d | 184/2281 | 419,494 (4.9) | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| Sitting time ≥ 6 h/d | 229/2484 | 649,377 (7.0) |
1.21 (0.99–1.47) |
1.25 (1.02–1.53) |
1.20 (0.98–1.46) |
|
| Pro-inflammatory diets (DII ≥ 0) | Sitting time < 6 h/d | 652/6896 | 1,329,387 (6.0) | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| Sitting time ≥ 6 h/d | 895/6764 | 8,344,986 (8.5) |
1.56 (1.41–1.72) |
1.50 (1.40–1.72) |
1.50 (1.35–1.66) |
|
| CVD Deaths | ||||||
| Anti-inflammatory diets (DII < 0) | Sitting time < 6 h/d | 36/2281 | 60,650 (0.7) | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| Sitting time ≥ 6 h/d | 50/2484 | 145,892 (1.6) |
1.33 (0.86–2.04) |
1.29 (0.83–2.01) |
1.21 (0.78–1.89) |
|
| Pro-inflammatory diets (DII ≥ 0) | Sitting time < 6 h/d | 62/6896 | 238,410 (1.1) | 1 [Reference] | 1 [Reference] | 1 [Reference] |
| Sitting time ≥ 6 h/d | 240/6764 | 2,201,005 (2.2) |
1.64 (1.34-2.00) |
1.57 (1.28–1.93) |
1.48 (1.20–1.82) |
|
Model 1: adjusted for age. Model 2: multivariable model additionally adjusted for sex, race, waist circumference, education level, family income-poverty ratio, smoking status, alcohol use, and physical activity. Model 3: additionally adjusted for the history of diabetes, chronic kidney disease, hypertension, hypercholesterolemia, use of antihypertensive, lipid-lowering, and antidiabetic medication, cardiovascular disease, and cancer. Abbreviation: CI, confidence interval; CVD, cardiovascular disease; DII, dietary inflammation index
Fig. 2.
The effect of DII on the association between sitting time with all-cause and CVD deaths. Analyses were adjusted for age, sex, race, waist circumference, education level, family income-poverty ratio, smoking status, alcohol use, physical activity, history of diabetes, chronic kidney disease, hypertension, hypercholesterolemia, use of antihypertensive, lipid-lowering, and antidiabetic medication, cardiovascular disease, and cancer. P value was tested on the multiplicative interaction term. Abbreviation: CI, confidence interval; CVD, cardiovascular disease; DII, dietary inflammation index; HR, hazard ratio
Subgroup analyses in the association between sedentary behavior and the risk of death stratified by dietary inflammation in different age or gender groups
We conducted subgroup analyses stratified by age and gender, and the adjusted HR and 95% CI values for the risk of death associated with sedentary behavior were presented in Table S8. In all age and gender subgroups, the relationship between sedentary behavior and increased risk of all-cause death was only observed among participants consuming pro-inflammatory diets, but not in those consuming anti-inflammatory diets. The relationship between sedentary behavior and the risk of CVD deaths also seemed to be stronger among individuals with pro-inflammatory diets, compared with those with anti-inflammatory diets. In addition, for participants with pro-inflammatory diets, stronger associations of prolonged sitting time (≥ 6 h/d) with increased risks of all-cause and CVD deaths were observed in the female subgroup (P for interaction < 0.05).
Discussion
During up to 13.3 years of follow-up, we observed an interaction between dietary inflammation and sedentary behavior on the risk of all-cause deaths. After stratifying participants according to dietary inflammation, sedentary behavior was correlated with an elevated risk of all-cause deaths only among participants consuming pro-inflammatory diets; no association was found among participants consuming anti-inflammatory diets. Similar results were observed for the risk of CVD deaths despite no significant interaction.
Our findings revealed an additive interaction between dietary inflammation and sedentary behavior on the risk of all-cause deaths. Prior research focused on the relationship between specific nutrients and sedentary behavior on the risk of death has yielded similar results [22, 23]. By analyzing the data of 10,610 adults in the US, Edwards et al. found that the greatest reduction in the risk of all-cause deaths was achieved by intakes of less-inflammatory diets concomitantly with adequate levels of PA (150 min/week of moderate-to-vigorous physical activity) [24]. These nutrients included vitamins such as A, B6, B12, and C, dietary fiber, carotene, niacin, thiamine, and riboflavin. However, an integrated assessment of the status of dietary inflammation was still missing. DII allowed us to consider diet as a whole and to assess the cumulative effects of multiple anti-inflammatory nutrients.
Indeed, sedentary behavior and dietary inflammation shared some common mechanisms of action. Both played a central role in determining adiposity levels and influencing chronic inflammation and metabolic dysfunction [25, 26], which in turn was correlated with increased risks of death. Considering this, the observed additive effect could be explained as a result of joint action of sedentary behavior and dietary inflammation.
It has been reported that dietary inflammation might contribute to an increased risk of death by triggering oxidative stress and thereby inflammatory responses [27, 28], which was in agreement with our study. After comparing the baseline data, we found that participants with pro-inflammatory diets had higher levels of NLR and SIRI. Such differences in levels of inflammatory markers suggested that systemic inflammation might play a role in the increased risk of death for those consuming pro-inflammatory diets.
According to our study, sedentary behavior seemed to be not significantly related to an elevated risk of all-cause deaths in participants with anti-inflammatory diets. However, the results were inconsistent with several previous studies [17–21]. A study conducted among UK Biobank participants provided evidence for the association between lower levels of PA and increased risks of all-cause and CVD deaths, regardless of the dietary quality [17]. Additionally, one previous study based on the general population also reported a positive relationship between sedentary behavior and the risk of death [4]. The discrepancy in results may be due to inadequate consideration of potential confounding factors, like dietary inflammation. However, interpretation of our results should also be treated with caution, and future studies were necessary to clarify this association.
Subgroup analysis indicated a stronger association between sedentary behavior and the risk of all-cause and CVD deaths in females among participants consuming pro-inflammatory diets. Homogeneity might be explained by gender-specific hormonal disparities. Specifically, estrogen has been reported for its cardiovascular protective effects [29], while androgens have been associated with an increased risk of CVD [30]. A relatively healthy status that females carried highlighted the effect of sedentary behavior on death.
Our results emphasized the benefits of individualized dietary management in the general population. According to our results, reducing sedentary time was important for ordinary people, especially for females. Moreover, for those who took up sedentary occupations, anti-inflammatory diets were strongly recommended to reduce the risk of death.
This study had several advantages. We covered the US national adult population, which helped guarantee representativeness. Moreover, consistent results in sensitivity analysis demonstrated the reliability and robustness of our conclusions.
This study also had some limitations. Firstly, information on diets and sitting time was self-reported. Thus, recall bias might exist. Second, it was hard to include all dietary nutrients associated with oxidative stress and inflammatory response through DII. Nevertheless, it was adequate for grouping participants into different levels of diet inflammation. Third, since our population included only US adults, caution was required in extrapolating results to other populations. Fourth, despite adjusting for critical covariates based on previous studies, there was still a high probability that certain confounders were not included, and causality was also difficult to determine due to the observational design. Finally, careful attention should be paid to interpreting the results considering the observational and exploratory nature of the study.
Conclusion
In conclusion, anti-inflammatory diets might mitigate the detrimental effects of sedentary behavior on survival in US adults. Therefore, the importance of anti-inflammatory diets should be emphasized, especially for individuals with sedentary lifestyles.
Electronic supplementary material
Below is the link to the electronic supplementary material.
Supplementary Material 1: Additional file 1: Table S1. Association of daily sitting time and DII with all-cause and CVD deaths among US adults. Table S2. Joint association of daily sitting time and DII with all-cause and CVD deaths among US adults. Table S3. The evaluation of additive interaction models between daily sitting time and DII on the risk of all-cause and CVD deaths. Table S4. Association of daily sitting time and DII with all-cause and CVD deaths among US adults (excluding follow-ups shorter than 3 years). Table S5. Joint association of daily sitting time and DII with all-cause and CVD deaths among US adults (excluding follow-ups shorter than 3 years). Table S6. Association of daily sitting time with all-cause and CVD deaths among US adults stratified by DII (excluding follow-ups shorter than 3 years). Table S7. The evaluation of additive interaction models between daily sitting time and DII on the risk of all-cause and CVD deaths (excluding follow-ups shorter than 3 years). Table S8. Association of sitting time with all-cause and CVD deaths stratified by DII in different age or gender groups. Figure S1. Dose-response association of daily sitting time and DII with all-cause and CVD deaths among US adults. Figure S2. The effect of DII on the association between daily sitting time with all-cause and CVD deaths among US adults (excluding follow-ups shorter than 3 years).
Acknowledgements
Invaluable contribution from all the participants and staff in the NHANES is deeply appreciated.
Abbreviations
- BMI
Body mass index
- CI
Confidence interval
- CKD
Chronic kidney disease
- CVD
Cardiovascular disease
- DII
Dietary inflammation index
- HR
Hazard ratio
- ICD
International classification of diseases
- NHANES
National health and nutrition examination survey
- PIR
Income-to-poverty ratio
- RCS
Restricted cubic splines
- RERI
Relative excess risk due to interaction
- WC
Waist circumference
Author contributions
H.W. contributed to the study’s conception, analyzed the data and drafted the manuscript. Z.Z., X.L., and Y.C. were responsible for data analysis, interpretation, and revision of the manuscript. All authors agreed to the submission of the manuscript.
Funding
Our study was supported by Scientific Research Funding of Tianjin Medical University Chu Hsien-I Memorial Hospital (ZXY-YJJ2023-2).
Data availability
No datasets were generated or analysed during the current study.
Declarations
Ethics approval and consent to participate
The protocols for NHANES were approved by the National Center for Health Statistics and Ethics Review Board, and informed written consent was obtained at enrollment from all the participants.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Contributor Information
Xiaoxin Liu, Email: m202276501@hust.edu.cn.
Ying Chen, Email: ying.chen@tmu.edu.cn.
References
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Supplementary Material 1: Additional file 1: Table S1. Association of daily sitting time and DII with all-cause and CVD deaths among US adults. Table S2. Joint association of daily sitting time and DII with all-cause and CVD deaths among US adults. Table S3. The evaluation of additive interaction models between daily sitting time and DII on the risk of all-cause and CVD deaths. Table S4. Association of daily sitting time and DII with all-cause and CVD deaths among US adults (excluding follow-ups shorter than 3 years). Table S5. Joint association of daily sitting time and DII with all-cause and CVD deaths among US adults (excluding follow-ups shorter than 3 years). Table S6. Association of daily sitting time with all-cause and CVD deaths among US adults stratified by DII (excluding follow-ups shorter than 3 years). Table S7. The evaluation of additive interaction models between daily sitting time and DII on the risk of all-cause and CVD deaths (excluding follow-ups shorter than 3 years). Table S8. Association of sitting time with all-cause and CVD deaths stratified by DII in different age or gender groups. Figure S1. Dose-response association of daily sitting time and DII with all-cause and CVD deaths among US adults. Figure S2. The effect of DII on the association between daily sitting time with all-cause and CVD deaths among US adults (excluding follow-ups shorter than 3 years).
Data Availability Statement
No datasets were generated or analysed during the current study.