Association Between Dietary Nutrient Intake and Chronic Obstructive Pulmonary Disease Severity: A Nationwide Population-Based Representative Sample

Figures & data

Figure 1. Study flow chart using data from the Korea National Health and Nutrition Examination Survey (KNHANES, 2013–2015).

Table 1. General characteristics of study participants.

	Men (n = 418)				Women (n = 284)
	Mild (n = 139)	Moderate (n = 247)	Severe to very severe (n = 32)	P-value	Mild (n = 138)	Moderate (n = 133)	Severe to very severe (n = 13)	P-value
Population size	1,475,157	2,216,667	266,999		1,131,391	1,126,575	118,413
Age, % (SE)				0.023^†				0.032*
40–49	31.8 (5.0)	20.8 (3.7)	0 (0)		39.9 (4.8)	20.4 (4.1)	0 (0)
50–59	31.4 (4.7)	28.6 (3.4)	44.1 (10.9)		24.3 (4.0)	27.1 (4.3)	38.1 (16.9)
60–69	23.0 (3.8)	27.5 (3.0)	33.9 (9.0)		21.7 (4.0)	32.8 (4.5)	39.5 (16.8)
≥70	13.7 (3.1)	23.2 (3.0)	22.0 (7.0)		14.2 (3.4)	19.7 (3.9)	22.3 (11.8)
Height, cm, mean (SE)	168.4 (0.7)	168.5 (0.4)	163.5 (1.3)	0.001^†,‡	155.6 (0.6)	155.9 (0.6)	152.0 (1.1)	0.001^†,‡
Body mass index, % (SE)				0.467				0.200
Underweight	0.5 (0.5)	2.1 (1.3)	6.3 (4.6)		2.6 (1.4)	2.6 (1.3)	4.2 (4.2)
Normal	35.1 (5.0)	36.7 (3.6)	29.6 (9.9)		50.4 (4.8)	44.0 (5.0)	16.9 (10.4)
Pre-obese	31.0 (4.4)	25.2 (3.5)	32.5 (10.3)		28.5 (4.5)	23.0 (4.3)	32.5 (17.7)
Obese	33.4 (4.6)	36.0 (3.9)	31.6 (8.8)		18.6 (3.9)	30.4 (4.4)	46.4 (16.7)
Smoking status, % (SE)				0.615				0.475
Never	11.3 (3.2)	8.5 (2.1)	4.5 (3.2)		89.3 (2.9)	94.1 (2.1)	100 (0)
Former	43.2 (4.8)	45.1 (3.9)	58.0 (10.8)		3.0 (1.5)	2.9 (1.5)	0 (0)
Current	45.5 (4.9)	46.3 (3.7)	37.5 (10.9)		7.7 (2.5)	3.0 (1.5)	0 (0)
Household income, % (SE)				0.153				0.187
Lowest (Q1)	16.5 (3.6)	23.8 (3.3)	42.2 (10.1)		20.3 (3.9)	34.0 (5.0)	43.5 (16.7)
Middle low (Q2)	31.6 (4.5)	28.2 (3.5)	32.3 (10.0)		27.2 (4.7)	23.7 (4.2)	9.1 (8.8)
Middle high (Q3)	27.1 (4.8)	25.5 (3.3)	15.2 (6.7)		26.7 (4.3)	19.3 (3.6)	38.4 (16.9)
Highest (Q4)	24.8 (4.2)	22.4 (3.3)	10.3 (5.7)		25.8 (4.3)	23.0 (4.1)	9.1 (8.8)
Residential area, % (SE)				0.244				0.842
Urban	81.2 (3.8)	74.8 (3.3)	69.2 (9.4)		81.0 (3.8)	78.3 (4.4)	82.7 (10.6)
Rural	18.8 (3.8)	25.2 (3.3)	30.8 (9.4)		19.0 (3.8)	21.7 (4.4)	17.3 (10.6)
Education, % (SE)				0.014^†,‡				0.008^†
Middle or low	34.3 (4.7)	41.4 (3.9)	69.5 (8.7)		36.0 (4.7)	52.3 (4.9)	90.9 (8.8)
High school	45.3 (4.9)	35.2 (3.6)	23.0 (7.7)		40.3 (4.8)	29.2 (4.5)	9.1 (8.8)
College or more	20.5 (3.7)	23.4 (3.4)	7.5 (4.3)		23.8 (4.1)	18.5 (3.9)	0 (0)
Spirometry
FEV1, liter, mean (SE)	3.01 (0.0)	2.32 (0.0)	1.27 (0.1)	<0.001*^,†,‡	2.33 (0.0)	1.70 (0.0)	0.92 (0.1)	<0.001*^,†,‡
Predicted FEV1, % (SE)	87.0 (0.5)	68.5 (0.6)	40.7 (1.4)	<0.001*^,†,‡	91.3 (0.8)	70.0 (0.8)	40.7 (2.1)	<0.001*^,†,‡
FVC, liter, mean (SE)	4.67 (0.1)	3.86 (0.0)	2.79 (0.1)	<0.001*^,†,‡	3.38 (0.1)	2.60 (0.1)	1.87 (0.1)	<0.001*^,†,‡
Predicted FVC, % (SE)	102.9 (0.7)	85.6 (0.6)	66.6 (2.1)	<0.001*^,†,‡	106.4 (1.0)	83.8 (1.0)	63.4 (2.5)	<0.001*^,†,‡
FEV1/FVC, % (SE)	64.5 (0.4)	59.8 (0.5)	46.1 (2.1)	<0.001*^,†,‡	68.7 (0.4)	65.2 (0.5)	50.4 (3.8)	<0.001*^,†,‡

Data are presented as weighted mean (SE) or weighted percentage (SE), unless otherwise stated.

Bold denotes P-value <0.05.

P-value <0.05 were considered significantly different: *mild vs. moderate, ^†mild vs. severe to very severe, ^‡moderate vs. severe to very.

SE, standard error; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity.

Table 2. Dietary macro-nutrient intake of the participants according to disease severity of COPD.

Men	Mild (n = 139)	Moderate (n = 247)	Severe to very severe (n = 32)	P-trend
Carbohydrate (g)				0.009
Mean (SE)	363.5 (11.4)	343.2 (8.3)	303.2 (14.5)
Median (IQR)	356.8 (284.6–432.9)	327.2 (263.1–415.4)	301.9 (234.0–370.7)
Fat (g)				0.061
Mean (SE)	44.8 (3.2)	40.3 (2.1)	29.2 (3.6)
Median (IQR)	33.3 (21.3–57.9)	32.6 (19.9–52.6)	26.1 (15.9–39.2)
Protein (g)				0.105
Mean (SE)	76.7 (3.2)	73.8 (2.6)	62.6 (5.1)
Median (IQR)	67.4 (51.7–94.6)	65.7 (47.3–89.9)	60.0 (36.5–85.7)
Fiber (g)				0.179
Mean (SE)	27.8 (1.3)	27.7 (1.0)	20.9 (1.7)
Median (IQR)	24.7 (18.4–34.4)	24.1 (18.4–34.7)	20.9 (14.6–26.4)
Women	Mild (n = 138)	Moderate (n = 133)	Severe to very severe (n = 13)	P-trend
Carbohydrate (g)				0.022
Mean (SE)	284.3 (8.3)	267.1 (8.9)	225.9 (18.9)
Median (IQR)	279.0 (213.0–346.3)	258.9 (193.7–320.2)	236.1 (171.1–273.7)
Fat (g)				0.113
Mean (SE)	31.6 (2.0)	30.8 (2.3)	23.1 (6.4)
Median (IQR)	26.5 (15.2–43.3)	22.9 (13.3–40.3)	12.7 (8.5–37.9)
Protein (g)				0.140
Mean (SE)	55.7 (2.4)	54.5 (2.5)	39.9 (6.1)
Median (IQR)	52.4 (33.9–68.3)	46.4 (33.6–67.0)	37.3 (29.5–43.0)
Fiber (g)				0.261
Mean (SE)	24.7 (1.2)	22.8 (1.0)	18.3 (1.8)
Median (IQR)	21.1 (14.7–13.6)	21.2 (13.4–29.9)	18.8 (13.7–22.5)

P-trend was calculated using Jonckheere–Terpstra trend test.

Data are presented as weighted mean (SE) or median (IQR).

Bold denotes P-value <0.05.

COPD, chronic obstructive pulmonary disease; SE, standard error; IQR, interquartile range.

Table 3. Dietary micro-nutrient intake of the participants according to disease severity of COPD.

Men	Mild (n = 139)	Moderate (n = 247)	Severe to very severe (n = 32)	P-trend
Vitamin A (µgRE)				0.019
Mean (SE)	780.9 (61.8)	827.8 (82.1)	469.9 (82.2)
Median (IQR)	576.9 (328.4–1064.3)	529.3 (308.6–915.9)	378.4 (186.2–621.8)
Beta carotene (mg)				0.039
Mean (SE)	3.9 (0.3)	4.4 (0.5)	2.4 (0.4)
Median (IQR)	3.0 (1.4–5.2)	2.6 (1.4–4.7)	1.7 (0.8–3.3)
Retinol (vitamin A1, µg)				0.043
Mean (SE)	100.9 (15.9)	91.1 (12.3)	57.6 (15.8)
Median (IQR)	57.2 (13.5–121.7)	44.8 (11.9–99.3)	26.3 (4.2–89.6)
Thiamin (vitamin B1, mg)				0.009
Mean (SE)	2.31 (0.1)	2.15 (0.1)	1.77 (0.1)
Median (IQR)	2.19 (1.57–2.81)	1.91 (1.47–2.62)	1.75 (1.16–2.31)
Riboflavin (vitamin B2, mg)				0.004
Mean (SE)	1.49 (0.1)	1.31 (0.0)	0.97 (0.1)
Median (IQR)	1.35 (0.80–1.99)	1.20 (0.78–1.66)	0.95 (0.61–1.19)
Niacin (vitamin B3, mg)				0.089
Mean (SE)	18.2 (0.9)	17.2 (0.7)	14.5 (1.3)
Median (IQR)	15.1 (11.3–21.5)	14.0 (10.4–21.4)	12.4 (8.3–19.6)
Vitamin C (mg)				0.111
Mean (SE)	108.7 (10.1)	106.8 (8.2)	65.4 (10.2)
Median (IQR)	66.4 (35.6–143.4)	64.4 (33.5–128.9)	39.6 (23.4–99.5)
Women	Mild (n = 138)	Moderate (n = 133)	Severe to very severe (n = 13)	P-trend
Vitamin A (µgRE)				0.684
Mean (SE)	943.4 (231.8)	742.2 (99.9)	428.4 (78.5)
Median (IQR)	440.1 (221.5–761.3)	434.4 (248.9–741.6)	418.8 (211.9–579.4)
Beta carotene (mg)				0.730
Mean (SE)	4.7 (1.3)	3.9 (0.6)	2.2 (0.4)
Median (IQR)	2.3 (1.0–3.9)	2.2 (1.1–3.9)	2.2 (0.9–3.0)
Retinol (vitamin A1, µg)				0.621
Mean (SE)	147.2 (51.9)	92.6 (24.9)	54.6 (16.9)
Median (IQR)	44.7 (11.8–84.4)	48.8 (11.8–99.9)	25.3 (2.8–128.1)
Thiamin (vitamin B1, mg)				0.147
Mean (SE)	1.74 (0.1)	1.67 (0.1)	1.29 (0.1)
Median (IQR)	1.53 (1.17–2.14)	1.54 (1.12–2.00)	1.36 (0.92–1.48)
Riboflavin (vitamin B2, mg)				0.463
Mean (SE)	1.12 (0.1)	1.13 (0.1)	0.75 (0.1)
Median (IQR)	1.02 (0.67–1.45)	1.00 (0.63–1.46)	0.61 (0.50–0.95)
Niacin (vitamin B3, mg)				0.050
Mean (SE)	13.7 (0.6)	12.3 (0.5)	10.3 (1.5)
Median (IQR)	11.7 (8.1–17.8)	11.5 (7.7–15.8)	7.8 (7.2–12.6)
Vitamin C (mg)				0.177
Mean (SE)	112.0 (8.3)	100.1 (7.6)	59.5 (14.9)
Median (IQR)	88.1 (32.0–170.9)	61.7 (30.3–163.1)	38.9 (27.7–77.3)

P-trend was calculated using Jonckheere–Terpstra trend test.

Data are presented as weighted mean (SE) or median (IQR).

Bold denotes P-value <0.05.

COPD, chronic obstructive pulmonary disease; SE, standard error; IQR, interquartile range.

Table 4. Association between predicted FEV₁% and nutrient intake in men (n = 418).

Predicted FEV1 (%)	Crude			Model 1*			Model 2^†
	Beta	SE	P-value	Beta	SE	P-value	Beta	SE	P-value
Carbohydrate (g)	7.441	5.116	0.147	6.583	4.527	0.147	6.381	5.001	0.203
Fat (g)	3.676	2.060	0.075	0.991	2.072	0.633	0.657	2.167	0.762
Protein (g)	7.048	3.379	0.038	4.317	3.440	0.211	3.801	3.606	0.293
Fiber (g)	7.343	3.157	0.021	6.561	3.066	0.033	6.467	3.281	0.050
Vitamin A (µgRE)	5.542	2.123	0.010	4.467	2.078	0.033	4.682	2.196	0.034
Beta-carotene (mg)	4.376	1.909	0.023	3.711	1.823	0.043	3.791	1.946	0.053
Retinol (vitamin A1, µg)	1.660	1.111	0.136	0.797	1.207	0.510	0.742	1.238	0.549
Thiamin (vitamin B1, mg)	8.154	3.577	0.023	5.695	3.438	0.099	5.387	3.726	0.149
Riboflavin (vitamin B2, mg)	7.007	2.551	0.006	5.291	2.626	0.045	4.874	2.761	0.079
Niacin (vitamin B3, mg)	5.054	3.120	0.106	3.287	3.035	0.280	2.827	3.300	0.392
Vitamin C (mg)	3.694	1.853	0.047	3.776	1.794	0.036	3.401	1.964	0.084

*Model 1 is adjusted for age and height.

^†Model 2 is adjusted for age, height, smoking status, household income, educational level, and residential area.

Each nutrient was individually analyzed and log-transformed because of its left-skewed distribution.

Bold denotes P-value <0.05.

FEV₁, forced expiratory volume in 1 second; SE, standard error.

Table 5. Association between predicted FEV₁% and nutrient intake in women (n = 284).

Predicted FEV1 (%)	Crude			Model 1*			Model 2^†
	Beta	SE	P-value	Beta	SE	P-value	Beta	SE	P-value
Carbohydrate (g)	12.984	6.181	0.037	11.101	5.855	0.059	10.279	5.846	0.080
Fat (g)	1.565	2.673	0.559	−2.501	2.757	0.365	−3.225	2.893	0.266
Protein (g)	6.184	4.553	0.176	1.829	4.464	0.682	0.773	4.365	0.860
Fiber (g)	4.727	4.220	0.264	2.250	4.325	0.604	1.635	4.162	0.695
Vitamin A (µgRE)	1.929	2.001	0.336	−0.038	2.090	0.986	−0.660	2.174	0.762
Beta-carotene (mg)	1.799	1.920	0.350	0.143	1.987	0.943	−0.449	2.075	0.829
Retinol (vitamin A1, µg)	−0.349	1.473	0.813	−1.224	1.457	0.402	−1.454	1.484	0.329
Thiamin (vitamin B1, mg)	7.487	5.520	0.177	3.216	5.316	0.546	1.565	5.085	0.759
Riboflavin (vitamin B2, mg)	2.829	3.545	0.426	−0.746	3.554	0.834	−1.647	3.552	0.643
Niacin (vitamin B3, mg)	9.947	4.639	0.033	4.977	4.966	0.317	2.924	4.759	0.540
Vitamin C (mg)	1.992	2.484	0.424	0.558	2.401	0.816	−0.399	2.382	0.867

*Model 1 is adjusted for age and height.

^†Model 2 is adjusted for age, height, smoking status, household income, educational level, and residential area.

Each nutrient was individually analyzed and log-transformed because of its left-skewed distribution.

Bold denotes P-value <0.05.

FEV₁, forced expiratory volume in 1 second; SE, standard error.

Table 6. Association between predicted FEV₁% and nutrient intake in elderly men (n = 254).

Predicted FEV1 (%)	Crude			Model 1*			Model 2^†
	Beta	SE	P-value	Beta	SE	P-value	Beta	SE	P-value
Carbohydrate (g)	17.426	11.529	0.134	19.503	5.923	0.001	21.492	6.045	<0.001
Fat (g)	0.085	4.130	0.984	3.938	2.995	0.190	5.551	3.084	0.074
Protein (g)	10.311	4.924	0.038	10.619	5.121	0.040	12.049	5.109	0.020
Fiber (g)	11.403	4.172	0.007	11.340	4.191	0.008	12.075	4.307	0.006
Vitamin A (µgRE)	3.992	2.820	0.159	3.942	2.858	0.170	5.036	2.920	0.086
Beta-carotene (mg)	4.410	2.569	0.088	4.327	2.613	0.100	5.087	2.642	0.056
Retinol (vitamin A1, µg)	−0.066	1.626	0.968	−0.002	1.667	0.999	0.547	1.666	0.743
Thiamin (vitamin B1, mg)	13.961	4.625	0.003	14.503	4.718	0.002	15.326	4.942	0.002
Riboflavin (vitamin B2, mg)	8.187	3.656	0.026	8.546	3.706	0.022	9.233	3.874	0.018
Niacin (vitamin B3, mg)	10.373	4.287	0.017	10.531	4.476	0.020	12.117	4.548	0.008
Vitamin C (mg)	4.768	2.330	0.042	4.968	2.376	0.038	6.157	2.644	0.021

*Model 1 is adjusted for age and height.

^†Model 2 is adjusted for age, height, smoking status, household income, educational level, and residential area.

Each nutrient was individually analyzed and log-transformed because of its left-skewed distribution.

Bold denotes P-value <0.05.

FEV₁, forced expiratory volume in 1 second; SE, standard error.

Table 7. Association between predicted FEV₁% and nutrient intake in elderly women (n = 133).

Predicted FEV1 (%)	Crude			Model 1*			Model 2^†
	Beta	SE	P-value	Beta	SE	P-value	Beta	SE	P-value
Carbohydrate (g)	17.426	11.529	0.134	18.225	11.350	0.112	19.252	11.072	0.085
Fat (g)	0.085	4.130	0.984	0.464	4.366	0.916	1.238	4.302	0.774
Protein (g)	2.303	7.474	0.759	2.858	7.514	0.705	4.460	6.897	0.525
Fiber (g)	0.777	6.699	0.908	1.729	6.869	0.802	1.627	7.053	0.818
Vitamin A (µgRE)	0.657	3.486	0.851	1.134	3.436	0.742	1.478	3.526	0.676
Beta-carotene (mg)	0.999	3.115	0.749	1.464	3.081	0.636	1.909	3.212	0.554
Retinol (vitamin A1, µg)	−0.255	2.507	0.919	−0.258	2.473	0.917	−0.118	2.371	0.960
Thiamin (vitamin B1, mg)	2.155	9.492	0.821	3.801	10.088	0.707	4.352	9.948	0.663
Riboflavin (vitamin B2, mg)	−2.929	5.702	0.609	−2.724	5.630	0.630	−2.242	5.553	0.687
Niacin (vitamin B3, mg)	−1.337	6.939	0.848	−0.732	7.103	0.918	0.467	6.955	0.947
Vitamin C (mg)	0.951	3.684	0.797	1.271	3.884	0.744	1.121	4.138	0.787

*Model 1 is adjusted for age and height.

^†Model 2 is adjusted for age, height, smoking status, household income, educational level, and residential area.

Each nutrient was individually analyzed and log-transformed because of its left-skewed distribution.

FEV₁, forced expiratory volume in 1 second; SE, standard error.