ABSTRACT
Chronic obstructive pulmonary disease (COPD) is a major respiratory disorder characterized by irreversible airflow limitation. The role of diet in the prevention and management of COPD is receiving increasing attention. This study aimed to examine the association between the composite intake of vegetables, fruits, meat, and fish and pulmonary function as well as COPD prevalence in a representative sample of Korean adults aged ≥ 40 years using data from the 7th Korea National Health and Nutrition Examination Survey. Higher vegetable intake was associated with significantly better pulmonary function parameters, including forced vital capacity (p < 0.001), forced vital capacity percent predicted (p = 0.050), forced expiratory volume (FEV) in 1 second (FEV1; p < 0.001), FEV1 percent predicted (p = 0.038), FEV in 6 seconds (p < 0.001), and peak expiratory flow (p < 0.001). Furthermore, individuals with a high combined intake of vegetables, fruits, meat, and fish demonstrated a 0.261-fold lower COPD prevalence than those without such intake (p = 0.039). The dietary inflammatory index (DII) was significantly lower among participants without COPD than among those with COPD (mean DII = −3.6947, p = 0.002), indicating that a diet rich in anti-inflammatory nutrients can help reduce COPD risk. These findings suggest that vegetable consumption supports improved respiratory function, and a composite dietary pattern incorporating various food groups may help reduce the prevalence of COPD in the adult population.
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Keywords: Chronic obstructive pulmonary disease; Korea National Health and Nutrition Examination Survey (KNHANES); Pulmonary function test; Dietary patterns; Inflammation
INTRODUCTION
Chronic obstructive pulmonary disease (COPD) is a progressive lung disorder that leads to airflow obstruction, commonly caused by airway and alveolar abnormalities that are exacerbated by risk factors such as smoking, occupational dust exposure, indoor air pollution, and recurrent respiratory infections [
1]. According to 2022 data from the Korean Statistical Office, the COPD-related mortality rate in Korea was 11.7% for both sexes combined [
2]. Although smoking remains the most well-known risk factor for respiratory diseases, environmental and occupational exposures—including air pollution and the use of biomass fuels—are also major contributors, with approximately 3 billion people worldwide exposed to respiratory risk through household energy sources [
1]. In urban areas, elevated levels of air pollutants further exacerbate the risk of respiratory diseases.
In addition to respiratory symptoms, COPD is often accompanied with nutritional complications such as weight loss and malnutrition [
3,
4]. It is estimated that 21%–40% of patients with COPD are malnourished, and low body weight is associated with a poor prognosis [
5,
6]. Dietary interventions are thus considered essential for COPD management. Antioxidant-rich diets, such as the Mediterranean diet, have been shown to improve respiratory health and reduce COPD incidence [
7,
8,
9,
10]. Garcia-Larsen et al. [
8] examined respiratory function and antioxidant intake in Chilean adults and revealed that a higher intake of catechins and fresh fruits was associated with improved respiratory function. Fischer et al. [
10] reported that maintaining a Mediterranean diet can reduce the incidence of COPD. In particular, n-3 fatty acids such as eicosapentaenoic acid and docosahexaenoic acid help modulate inflammation and are associated with better pulmonary function [
11]. Increased consumption of fruits, vegetables, and fish has been linked to improved spirometric parameters such as forced expiratory volume (FEV) in 1 second (FEV
1), whereas red meat intake has been associated with greater COPD prevalence [
12,
13].
Although existing literature supports the role of individual nutrients or food groups in respiratory health, only a few studies have explored the combined effect of multiple dietary components, particularly in the Korean population. Therefore, this study aimed to investigate the association between the composite intake of vegetables, fruits, meat, and fish and pulmonary function parameters among Korean adults using data from the Korea National Health and Nutrition Examination Survey (KNHANES). In addition, we examined whether the prevalence of COPD differed according to the consumption patterns of various combinations of food groups.
MATERIALS AND METHODS
Study participants
This study was based on data from the 7th KNHANES, conducted from 2016 to 2018. This study examined the data of adults aged 40–79 years who participated in the survey, excluding those with an energy intake below 500 kcal or above 5,000 kcal and those with undetermined pulmonary function. Data from 8,280 adults were selected for this study (
Supplementary Figure 1). The non-COPD group comprised individuals with normal pulmonary function, whereas the COPD group comprised those diagnosed with restrictive or obstructive ventilatory impairment. Dietary intake of vegetables, fruits, meat, and fish was categorized into quartiles according to the level of intake: Q1 (< 25th percentile), Q2 (25th–49th percentiles), Q3 (50th–74th percentiles), and Q4 (≥ 75th percentile). For combined intake analysis, the participants were categorized into 2 groups according to their intake levels across all 4 food groups: those whose intake of all 4 food types fell below the 25th percentile were classified as the “low-intake group” and those whose intake fell at or above the 75th percentile were classified as the “high-intake group.”
The pulmonary function test in the KNHANES has been conducted using Vyntus Spiro since 2016. Indices of respiratory function included forced vital capacity (FVC), FEV1, FEV in 6 seconds (FEV6), peak expiratory flow (PEF), and forced expiratory flow between 25% and 75% of the FVC (FEF25–75). For analysis, in accordance with the COPD diagnostic criteria, we classified individuals with FEV1/FVC ratios of < 0.7 as the COPD group and those with FEV1/FVC ratios of ≥ 0.7 as the non-COPD group. In this study, participants with restrictive ventilatory defects, characterized by a normal FEV1/FVC ratio accompanied with reduced FVC, were included in the COPD group. Participants with uninterpretable spirometry results were excluded from the study.
Dietary and nutrient intake survey
The nutritional survey was conducted by the KNHANES team, who visited the surveyed households 1 day before the survey and used the 24-hour recall method to obtain information about food intake. Individual total calorie intake and nutrient intake statuses were based on the 2015 Korean Dietary Reference Intakes for Koreans. Nutrient intake levels were calculated from the processed data obtained in the food intake survey; these nutrients included energy, protein, fat, saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, n-3 fatty acids, n-6 fatty acids, cholesterol, carbohydrates, dietary fiber, sugars, calcium, phosphorus, iron, sodium, vitamin A (retinol activity equivalents), thiamin, riboflavin, niacin, folate, and vitamin C.
Dietary inflammatory index (DII)
In the KNHANES, 21 nutrients were used to calculate the DII. These nutrients included carbohydrates, protein, total fat, saturated fat, monounsaturated fatty acids, polyunsaturated fatty acids, n-3 fatty acids, n-6 fatty acids, cholesterol, dietary fiber, vitamin A, vitamin B
1, vitamin B
2, niacin, folic acid, vitamin C, iron, vitamin D, magnesium, and zinc. The DII was calculated using a scoring system developed by Shivappa et al. [
14]:
Statistical analysis was conducted using SPSS Statistics 27.0 (SPSS, Inc., Chicago, IL, USA). For data processing, we applied a complex sample design that was based on the results of the KNHANES and used weighting methods recommended by the Korea Centers for Disease Control and Prevention. The basic characteristics, intake levels, and respiratory function parameters of the study participants were evaluated using complex sample analysis. General characteristics, dietary intake, and pulmonary function were described using means ± standard errors for continuous variables or using numbers with percentages for categorical variables. Differences in overall characteristics between the 2 groups were determined via generalized linear model for continuous variables or via Rao–Scott χ2 test for categorical variables. Logistic regression analysis was conducted to evaluate the association between food intake and the odds of COPD. A p value of < 0.05 was considered to indicate statistical significance for all analyses.
RESULTS
General characteristics of the study population
The mean age of the participants was higher in the COPD group (63.0 years) than in the non-COPD group (54.7 years). The proportion of individuals with COPD increased with advancing age. A higher proportion of males (64.6%) was observed in the COPD group. Moreover, the prevalence of current smoking was significantly greater in the COPD group than in the non-COPD group (57.7% vs. 36.6%). Because of these differences, age, sex, and smoking status were considered covariates and adjusted for in the subsequent analyses (
Table 1).
Table 1General characteristics of the study population by COPD
Table 1
|
Characteristics |
COPD (n = 2,309) |
Non-COPD (n = 5,971) |
p value*
|
|
Age (yr) |
63.02 ± 0.32 |
54.74 ± 0.20 |
< 0.000 |
|
Age group (yr) |
|
|
< 0.000 |
|
40s |
249 (14.4) |
1,997 (38.2) |
|
50s |
478 (27.0) |
1,854 (33.1) |
|
60s |
719 (26.8) |
1,366 (18.8) |
|
Over 70s |
775 (31.9) |
670 (9.8) |
|
Sex |
|
|
< 0.000 |
|
Male |
1,410 (64.6) |
2,091 (42.3) |
|
Female |
899 (35.4) |
3,880 (57.7) |
|
Current smoking status |
|
|
< 0.000 |
|
Yes |
1,258 (57.7) |
1,872 (36.6) |
|
Sometimes |
24 (1.2) |
93 (1.9) |
|
No |
1,006 (41.1) |
3,981 (61.5) |
Pulmonary function characteristics by COPD status
As presented in
Table 2, comparisons of pulmonary function parameters between the COPD and non-COPD groups revealed that the COPD group exhibited significantly lower values across multiple parameters. Specifically, the FVC was higher in the non-COPD group than in the COPD group (3.57 vs. 3.10 L; p < 0.001). Similarly, the non-COPD group demonstrated higher FEV
1 (94.23 vs. 75.04; p < 0.000) and FEV
1/FVC ratio (0.79 vs. 0.73; p < 0.000). Additional pulmonary function indicators, including forced vital capacity percent predicted (FVCP), FEV
1 percent predicted (FEV
1P), FEV
6, FEF
25–75, and PEF, were significantly higher in the non-COPD group, indicating better overall respiratory function.
Table 2Pulmonary function characteristics by COPD status
Table 2
|
Pulmonary function |
COPD (n = 2,309) |
Non-COPD (n = 5,971) |
p value*
|
|
FVC |
3.10 ± 0.015 |
3.57 ± 0.007 |
< 0.000*
|
|
FVCP |
80.07 ± 0.343 |
92.97 ± 0.139 |
< 0.000*
|
|
FEV1
|
2.25 ± 0.010 |
2.80 ± 0.005 |
< 0.000*
|
|
FEV1P |
75.04 ± 0.282 |
94.23 ± 0.148 |
< 0.000*
|
|
FEV1/FVC |
0.73 ± 0.002 |
0.79 ± 0.001 |
< 0.000*
|
|
FEV6
|
2.98 ± 0.014 |
3.50 ± 0.007 |
< 0.000*
|
|
FEF25–75
|
1.86 ± 0.020 |
2.71 ± 0.011 |
< 0.000*
|
|
PEF |
6.05 ± 0.037 |
7.22 ± 0.022 |
< 0.000*
|
Comparison of dietary intake between the COPD and non-COPD groups
Table 3 presents a comparison of food consumption levels between the COPD and non-COPD groups. No significant difference was observed in total energy intake between the 2 groups (p = 0.629), and there were no statistically significant differences across any food groups. As previous studies [
15,
16] indicated associations between specific dietary components and lung function, we further assessed the relationship of the intake of vegetables, fruits, meats, and fish with changes in pulmonary function and the presence of COPD.
Table 3Comparison of dietary intake between COPD and non-COPD groups
Table 3
|
Intake |
COPD (n = 2,309) |
Non-COPD (n = 5,971) |
p value*
|
|
Energy (kcal) |
1,938.38 ± 20.60 |
1,949.49 ± 13.39 |
0.629 |
|
Vegetable (g) |
327.37 ± 6.15 |
340.00 ± 3.76 |
0.068 |
|
Fruit (g) |
273.11 ± 9.35 |
280.52 ± 5.54 |
0.484 |
|
Meat (g) |
124.36 ± 4.52 |
127.34 ± 2.68 |
0.576 |
|
Fish (g) |
139.05 ± 6.58 |
130.98 ± 3.06 |
0.258 |
|
Grain (g) |
284.09 ± 4.04 |
288.63 ± 2.51 |
0.324 |
|
Starch (g) |
68.08 ± 4.91 |
74.78 ± 2.93 |
0.241 |
|
Sugar (g) |
10.04 ± 0.53 |
10.47 ± 0.29 |
0.490 |
|
Legume (g) |
54.11 ± 2.40 |
53.52 ± 1.61 |
0.841 |
|
Mushroom (g) |
14.18 ± 1.12 |
14.87 ± 0.72 |
0.609 |
|
Egg (g) |
46.40 ± 1.74 |
49.18 ± 0.96 |
0.152 |
|
Milk (g) |
189.78 ± 6.76 |
192.41 ± 3.93 |
0.748 |
Respiratory function according to quartiles of food intake in the COPD group
Respiratory function was evaluated according to quartiles of food intake. An increase in vegetable consumption was associated with improved pulmonary function across multiple parameters, including FVC, FVCP, FEV
1, FEV
1P, FEV
6, and PEF. The mean FVC was 3.06 L in the lowest quartile (< 25th percentile) of vegetable intake and 3.22 L in the highest quartile (> 75th percentile; p < 0.001). Across these quartiles, we also observed significant increases in FEV
1 (from 2.15 to 2.28 L; p < 0.000), FEV
1P (from 74.46 to 76.69; p = 0.009), FEV
6 (from 2.91 to 3.07 L; p < 0.000), and PEF (from 5.91 to 6.26 L; p = 0.002). An increase in meat consumption was associated with improvement only in FEV
1. In contrast, no significant associations were observed between respiratory function and the intake of fruit or fish (
Table 4).
Table 4Respiratory function according to quartiles of food intake in chronic obstructive pulmonary disease group
Table 4
|
Pulmonary function |
Vegetable |
Fruit |
Meat |
Fish |
|
Q1 |
Q2 |
Q3 |
Q4 |
p for trend*
|
Q1 |
Q2 |
Q3 |
Q4 |
p for trend |
Q1 |
Q2 |
Q3 |
Q4 |
p for trend |
Q1 |
Q2 |
Q3 |
Q4 |
p for trend |
|
FVC |
3.06 ± 0.030a
|
3.14 ± 0.026a
|
3.15 ± 0.028a
|
3.22 ± 0.028b
|
0.001 |
3.08 ± 0.033 |
3.07 ± 0.031 |
3.12 ± 0.030 |
3.14 ± 0.037 |
0.338 |
3.19 ± 0.036 |
3.21 ± 0.032 |
3.18 ± 0.037 |
3.28 ± 0.034 |
0.209 |
3.16 ± 0.031 |
3.12 ± 0.029 |
3.20 ± 0.028 |
3.20 ± 0.031 |
0.157 |
|
FVCP |
78.24 ± 0.644 |
79.34 ± 0.654 |
79.55 ± 0.589 |
80.28 ± 0.608 |
0.148 |
79.39 ± 0.746 |
79.14 ± 0.747 |
79.32 ± 0.680 |
79.36 ± 0.767 |
0.995 |
79.40 ± 0.773 |
79.93 ± 0.696 |
79.38 ± 0.796 |
79.88 ± 0.728 |
0.902 |
79.85 ± 0.740 |
78.01 ± 0.647 |
79.96 ± 0.619 |
80.00 ± 0.652 |
0.079 |
|
FEV1
|
2.15 ± 0.019a
|
2.23 ± 0.017b
|
2.25 ± 0.019b
|
2.28 ± 0.018c
|
< 0.000 |
2.21 ± 0.021 |
2.20 ± 0.022 |
2.22 ± 0.021 |
2.25 ± 0.022 |
0.488 |
2.28 ± 0.023 |
2.27 ± 0.020 |
2.26 ± 0.024 |
2.36 ± 0.022 |
0.010 |
2.23 ± 0.021 |
2.22 ± 0.020 |
2.27 ± 0.020 |
2.27 ± 0.018 |
0.213 |
|
FEV1P |
74.46 ± 0.578a
|
76.20 ± 0.548a
|
76.89 ± 0.564b
|
76.69 ± 0.566c
|
0.009 |
77.06 ± 0.643 |
76.47 ± 0.757 |
76.05 ± 0.652 |
76.41 ± 0.676 |
0.693 |
76.22 ± 0.721 |
76.22 ± 0.653 |
75.62 ± 0.654 |
77.00 ± 0.609 |
0.502 |
76.32 ± 0.744 |
75.13 ± 0.599 |
76.46 ± 0.576 |
76.67 ± 0.511 |
0.262 |
|
FEV1/FVC |
0.71 ± 0.004 |
0.72 ± 0.004 |
0.72 ± 0.004 |
0.71 ± 0.004 |
0.285 |
0.72 ± 0.005 |
0.72 ± 0.005 |
0.72 ± 0.005 |
0.72 ± 0.005 |
0.761 |
0.72 ± 0.005 |
0.72 ± 0.005 |
0.72 ± 0.005 |
0.72 ± 0.005 |
0.585 |
0.71 ± 0.005 |
0.72 ± 0.004 |
0.71 ± 0.004 |
0.72 ± 0.005 |
0.797 |
|
FEV6
|
2.91 ± 0.026a
|
3.00 ± 0.023b
|
3.00 ± 0.025b
|
3.07 ± 0.025c
|
< 0.000 |
2.94 ± 0.028 |
2.94 ± 0.027 |
2.97 ± 0.027 |
3.01 ± 0.032 |
0.346 |
3.05 ± 0.032 |
3.06 ± 0.028 |
3.04 ± 0.033 |
3.13 ± 0.029 |
0.108 |
3.00 ± 0.027 |
2.97 ± 0.025 |
3.05 ± 0.025 |
3.05 ± 0.027 |
0.104 |
|
FEF25–75
|
1.64 ± 0.033a
|
1.71 ± 0.035a
|
1.77 ± 0.038b
|
1.68 ± 0.033a
|
0.064 |
1.75 ± 0.046 |
1.72 ± 0.042 |
1.70 ± 0.038 |
1.76 ± 0.046 |
0.674 |
1.78 ± 0.046 |
1.73 ± 0.040 |
1.73 ± 0.043 |
1.86 ± 0.047 |
0.146 |
1.73 ± 0.040 |
1.68 ± 0.040 |
1.73 ± 0.039 |
1.71 ± 0.035 |
0.825 |
|
PEF |
5.91 ± 0.070a
|
6.15 ± 0.068a
|
6.22 ± 0.070a
|
6.26 ± 0.073b
|
0.002 |
6.24 ± 0.087 |
5.98 ± 0.080 |
6.16 ± 0.071 |
6.22 ± 0.093 |
0.087 |
6.33 ± 0.083 |
6.26 ± 0.081 |
6.35 ± 0.088 |
6.52 ± 0.087 |
0.198 |
6.18 ± 0.077 |
6.09 ± 0.084 |
6.31 ± 0.078 |
6.25 ± 0.073 |
0.229 |
Combined effects of multiple food groups on COPD risk
Table 5 presents an analysis of the combined effects of the intake of vegetables, fruits, meat, and fish on the risk of COPD, categorized by quartiles. When all 4 food groups—vegetables, fruits, meat, and fish—were consumed by individuals with the highest overall consumption across these groups (Q4), the odds ratio (OR) for COPD was significantly lower, with a 74% reduction in the associated risk (OR, 0.261; p = 0.039). However, no statistically significant associations were observed when only 2 food groups were combined (i.e., vegetables and fruits; vegetables and meat; vegetables and fish; fruits and meat; fruits and fish; or meat and fish). Similarly, combinations of 3 food groups—such as vegetables, fruits, and meat; vegetables, fruits, and fish; vegetables, meat, and fish; or fruits, meat, and fish—did not yield significant results.
Table 5Combined effects of multiple food groups on chronic obstructive pulmonary disease risk
Table 5
|
Combined Q4 group |
Odds ratio (95% CI) |
p value*
|
|
Vegetable, fruit, meat, fish |
0.261 (0.073–0.932) |
0.039 |
|
Vegetable, fruit |
1.165 (0.858–1.582) |
0.328 |
|
Vegetable, meat |
1.034 (0.746–1.432) |
0.841 |
|
Vegetable, fish |
1.098 (0.824–1.464) |
0.522 |
|
Fruit, meat |
0.919 (0.605–1.395) |
0.690 |
|
Fruit, fish |
0.800 (0.550–1.163) |
0.242 |
|
Meat, fish |
0.786 (0.535–1.156) |
0.221 |
|
Vegetable, fruit, meat |
1.074 (0.526–2.192) |
0.844 |
|
Vegetable, fruit, fish |
0.903 (0.489–1.667) |
0.743 |
|
Vegetable, meat, fish |
1.444 (0.759–2.747) |
0.261 |
|
Fruit, meat, fish |
0.376 (0.130–1.093) |
0.072 |
DII and its association with COPD
We calculated DIIs for 21 nutrients. Of these, 7 (energy, carbohydrates, protein, total fat, saturated fatty acids, cholesterol, and iron) were classified as proinflammatory dietary components and the other 14 (monounsaturated fatty acids, polyunsaturated fatty acids, n-3 fatty acids, n-6 fatty acids, dietary fiber, vitamin A, vitamin B
1, vitamin B
2, niacin, folate, vitamin C, vitamin D, magnesium, and zinc) as anti-inflammatory components. As shown in
Table 6, the non-COPD group showed a significantly higher intake of anti-inflammatory nutrients than the COPD group (p = 0.002). These findings suggest that an anti-inflammatory dietary pattern, in combination with the previously identified beneficial food group intake, may help reduce the risk of COPD.
Table 6DII and its association with COPD
Table 6
|
DII |
COPD |
Non-COPD |
p value*
|
|
Total |
−3.4885 ± 0.060 |
−3.6947 ± 0.042 |
0.002 |
|
Energy |
0.0777 ± 0.001 |
0.0815 ± 0.001 |
0.067 |
|
Carbohydrate |
0.0592 ± 0.001 |
0.0616 ± 0.000 |
0.097 |
|
Protein |
0.0075 ± 0.001 |
0.0078 ± 0.000 |
0.328 |
|
Fat |
0.0630 ± 0.001 |
0.0682 ± 0.001 |
0.009 |
|
Saturated fatty acid |
0.0572 ± 0.001 |
0.0616 ± 0.001 |
0.035 |
|
Mono-unsaturated fatty acid |
−0.0008 ± 0.000 |
−0.0009 ± 0.000 |
0.028 |
|
Poly-unsaturated fatty acid |
−0.1166 ± 0.002 |
−0.1245 ± 0.001 |
0.019 |
|
ω−3 fatty acid |
−0.2731 ± 0.003 |
−0.2776 ± 0.002 |
0.268 |
|
ω−6 fatty acid |
−0.0715 ± 0.000 |
−0.0731 ± 0.002 |
0.015 |
|
Cholesterol |
0.0305 ± 0.001 |
0.0325 ± 0.001 |
0.317 |
|
Dietary fiber |
−0.5053 ± 0.009 |
−0.5342 ± 0.006 |
0.006 |
|
Vitamin A |
−0.1530 ± 0.002 |
−0.1550 ± 0.001 |
0.402 |
|
Vitamin B1
|
−0.0388 ± 0.000 |
−0.0398 ± 0.000 |
0.039 |
|
Vitamin B2
|
−0.5521 ± 0.009 |
−0.5811 ± 0.006 |
0.009 |
|
Niacin |
−0.0773 ± 0.000 |
−0.0789 ± 0.000 |
0.016 |
|
Folate |
−0.1249 ± 0.002 |
−0.1294 ± 0.001 |
0.064 |
|
Vitamin C |
−0.1195 ± 0.003 |
−0.1286 ± 0.002 |
0.013 |
|
Iron |
0.0143 ± 0.000 |
0.0149 ± 0.000 |
0.034 |
|
Vitamin D |
−0.1265 ± 0.005 |
−0.1238 ± 0.003 |
0.665 |
|
Magnesium |
−0.2561 ± 0.002 |
−0.2604 ± 0.001 |
0.147 |
|
Zinc |
−1.3823 ± 0.047 |
−1.5154 ± 0.031 |
0.013 |
DISCUSSION
This study investigated the association between the intake of vegetables, fruits, meat, and fish and pulmonary function parameters in a representative sample of 8,280 individuals aged ≥ 40 years using data from the 7th KNHANES.
Previous research has suggested that individuals with COPD experience impaired chewing and swallowing functions, which can alter breathing patterns and reduce food intake due to discomfort or dyspnea [
17]. Gastric distension has also been reported to lower functional residual capacity, further contributing to eating difficulties [
12]. Moreover, patients with COPD are often exposed to heightened oxidative stress, particularly due to smoking, which can induce inflammatory responses and diminish pulmonary function [
18]. In this context, consumption of antioxidant-rich foods such as fruits and vegetables has been recommended because of their potential to mitigate respiratory decline [
19].
Our results demonstrated that increased vegetable intake was associated with improved pulmonary function, specifically FVC, FVCP, FEV
1, FEV
1P, FEV
6, and PEF values. This association may be partially explained by the presence of dietary fiber in vegetables, which has been suggested to exert anti-inflammatory effects through the production of short-chain fatty acids such as butyrate by gut microbiota [
20]. These metabolites are believed to contribute to immune regulation and inflammation control, which could play a role in respiratory health. Moreover, vitamin C, which is abundant in vegetables, has been associated with lung development and a reduction in airway hyperresponsiveness [
20].
By further examining the inflammatory potential of the diet, we found that the non-COPD group consumed a significantly higher amount of anti-inflammatory nutrients than the COPD group, indicating that dietary inflammation plays a role in lung function impairment. These findings support the hypothesis that an anti-inflammatory dietary pattern contributes to respiratory health by reducing systemic and airway inflammation.
Our study revealed that although individual food groups were not consistently associated with reduction in COPD risk, a high combined intake of vegetables, fruits, meat, and fish significantly lowered the risk of COPD. These findings are supported by previous cohort studies highlighting the respiratory benefits of diverse food group consumption. For instance, the MORGEN study revealed that a higher intake of fruits and fish was linked to reduced COPD-related mortality [
20], and a study analyzing data from the National Health and Nutrition Examination Survey revealed that higher DII scores, which are indicative of proinflammatory diets, were associated with an increased risk of early COPD and reduced lung function [
21,
22]. These results underscore the importance of a balanced diet rich in anti-inflammatory foods for mitigating COPD risk.
As respiratory muscle exertion increases, protein intake becomes particularly relevant in COPD management, highlighting the role of meat and fish in meeting dietary protein requirements [
7]. However, it is important to distinguish healthy protein sources from processed meats, as the latter has been linked to a higher prevalence of COPD [
5].
Although individual food groups may confer certain protective effects, participants in our study with high intake levels across all 4 food groups had a significantly lower risk of COPD. This suggests that the synergistic effects of a diverse dietary pattern play a more critical role in respiratory health than reliance on a single food group, and our findings emphasize the importance of a balanced and varied diet.
CONCLUSION
In conclusion, the findings of this study suggest that a well-balanced, mixed diet rich in vegetables, fruits, meat, and fish—particularly one characterized by anti-inflammatory properties—may help improve respiratory function and reduce COPD risk. These results support the incorporation of comprehensive, anti-inflammatory dietary recommendations into nutrition education materials for individuals with or at risk of COPD, with a focus on enhancing overall dietary quality rather than emphasizing individual nutrients or food groups.
NOTES
-
Conflict of Interest: The authors declare that they have no competing interests.
-
Author Contributions:
Conceptualization: Park S, Park H.
Data curation: Park S.
Formal analysis: Park S.
Supervision: Park H.
Validation: Park H.
Visualization: Park S.
Writing - original draft: Park S.
Writing - review & editing: Park H.
SUPPLEMENTARY MATERIAL
Supplementary Figure 1
Flow chart of participant selection. Participants with restrictive or obstructive ventilatory impairments based on pulmonary function test results were classified as the COPD group, while those with normal function were categorized as the non-COPD group.
cnr-14-182-s001.ppt
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