Association of dietary fiber with subjective sleep quality in hemodialysis patients: a cross-sectional study in China

Figures & data

Figure 1. Flow chart indicates patient enrollment.

Table 1. Baseline characteristics of study participants according to dietary fibre intake levels.

Characteristics	All patients	Tertiles of total fiber intake
		T1 (< 11.52)	T2 (11.52–16.86)	T3 (≥ 16.86)
Poor sleep quality/No. of patients	461/741	164/247	148/247	149/247
Demographics
Age (years)	60 ± 14	60 ± 14	60 ± 14	60 ± 13
Male (n, %)	281 (37.92)	101 (40.89)	85 (34.41)	95 (38.46)
Body mass index (kg/m^2)	24.13 ± 4.16	24.18 ± 4.22	24.10 ± 3.95	24.10 ± 4.32
Physical activity (MET/min/week)	297 (0–1188)	297 (0–990)	231 (0–1386)	346.5 (0–933)
Educational level (n, %)
Junior secondary or below	359 (48.45)	131 (53.04)	112 (45.34)	116 (46.96)
Senior high school/technical secondary school	199 (26.86)	60 (24.29)	70 (28.34)	69 (27.94)
Junior college/university or above	183 (24.70)	56 (22.67)	65 (26.32)	62 (25.10)
Annual family income (RMB thousand yuan), (n, %)
<50	216 (29.15)	58 (23.48)	84 (34.01)	74 (29.96)
50 to <100	340 (45.88)	122 (49.39)	107 (43.32)	111 (44.94)
≥100	185 (24.97)	67 (27.13)	56 (22.67)	62 (25.10)
Current or former smoker, (n, %)	327 (44.13)	108 (43.72)	112 (45.34)	107 (43.32)
Current or former drinker, (n, %)	261 (35.22)	86 (34.82)	85 (34.41)	90 (36.44)
Co-morbid conditions, (n, %)
Diabetes	309 (41.70)	94 (38.06)	118 (47.77)	97 (39.27)
Hypertension	629 (84.89)	211 (85.43)	207 (83.81)	211 (85.43)
CVD	457 (61.67)	148 (59.92)	157 (63.56)	152 (61.54)
Laboratory parameters
Hemoglobin (g/L)	113 (105–121)	113 (106–120)	114 (106–123)	113 (104–123)
Albumin (g/L)	41.2 (39.2–43.3)	41.3 (38.9–43.4)	41.1 (39.1–43.3)	41.2 (39.3–43.2)
Calcium (mmol/L)	2.14 (2.03–2.25)	2.14 (2.03–2.25)	2.15 (2.03–2.25)	2.13 (2.04–2.24)
Phosphorus (mmol/L)	2.03 (1.66–2.44)	2.03 (1.63–2.41)	2.04 (1.76–2.44)	1.99 (1.59–2.46)
Creatinine (μmol/L)	891.47 ± 254.98	874.04 ± 248.29	908.94 ± 261.73	891.44 ± 254.59
C-reactive protein (mg/L)	3.3 (3.3–7.8)	3.30 (3.30–8.48)	3.30 (3.30–8.35)	3.30 (3.30–7.09)
Ferritin (mg/L)	97.97 (45.23–180.96)	89 (40.04–207.09)	98.79 (45.26–181.57)	101.75 (48.98–161.22)
Urea nitrogen (mmol/L)	28.30 (24.44–32.67)	27.99 (24.59–33.03)	29.04 (24.42–33.11)	27.91 (24.17–31.96)
Time on dialysis (months)	49.7 (22.2–99.2)	49.7 (21.8–89.3)	46.3 (24.1–96.6)	53.77 (20.3–109.7)
SpKt/Vurea	1.33 (1.17–1.49)	1.33 (1.18–1.48)	1.33 (1.17–1.48)	1.33 (1.17–1.49)

Data presented as mean ± SD (standard deviation) or median (quartile1- quartile3) (continuous variables) or number (%) (categorical variables).

Abbreviations: MET, metabolic equivalents of task.

Table 2. Diet characteristics of study participants according to dietary fibre intake levels.

Characteristics	All patients	Tertiles of total fiber intake
		T1 (< 11.52)	T2 (11.52–16.86)	T3 (≥ 16.86)
Poor sleep quality/No. of patients	461/741	164/247	148/247	149/247
Total energy intake (kcal/day)	1415.56 (1093.08–1784.47)	1020.74 (823.51–1277.46)	1415.20 (1195.66–1643.94)	1868.18 (1547.75–2232.51)
Protein intake (g/day)	58.51 (45.97–74.07)	43.93 (32.62–53.12)	58.20 (49.57–68.07)	77.71 (63.60–90.61)
Total soluble fiber intake (g/day)	4.63 (3.20–6.80)	2.78 (2.24–3.34)	4.75 (4.05–5.52)	7.49 (6.34–8.92)
Total insoluble dietary fiber (g/day)	9.25 (6.88–12.57)	5.85 (4.59–7.07)	9.26 (8.34–10.17)	14.12 (12.54–17.31)
Total dietary fiber in vegetables (g/day)	3.54 (2.14–5.19)	2.11 (1.48–3.25)	3.54 (2.56–4.64)	5.61 (3.94–8.03)
Soluble dietary fiber in vegetables(g/day)	1.39 (0.82–2.20)	0.85 (0.60–1.28)	1.41 (0.97–2.01)	2.24 (1.62–3.23)
Insoluble dietary fiber in vegetables(g/day)	2.04 (1.28–3.05)	1.24 (0.88–1.85)	2.11 (1.53–2.67)	3.31 (2.31–4.68)
Total dietary fiber in fruits (g/day)	2.78 (1.39–5.21)	1.40 (0.73–2.22)	2.80 (1.49–4.12)	6.14 (3.62–8.74)
Soluble dietary fiber in fruits (g/day)	0.79 (0.39–1.44)	0.41 (0.20–0.65)	0.78 (0.39–1.25)	1.63 (0.92–2.35)
Insoluble dietary fiber in fruits (g/day)	1.95 (0.96–3.81)	0.99 (0.53–1.57)	1.96 (1.01–3.13)	4.46 (2.59–6.37)
Total dietary fiber in cereal (g/day)	3.37 (2.34–4.69)	2.38 (1.85–3.26)	3.55 (2.52–4.76)	4.44 (3.34–5.79)
Soluble dietary fiber in cereal (g/day)	0.30 (0–0.70)	0.23 (0–0.46)	0.30 (0–1.00)	0.46 (0.14–1.14)
Insoluble dietary fiber in cereal (g/day)	2.81 (2.02–3.91)	2.16 (1.57–2.82)	2.85 (2.15–3.93)	0.46 (0.14–1.14)
Total dietary fiber in beans (g/day)	1.16 (0.67–1.92)	0.78 (0.31–1.15)	1.25 (0.79–1.94)	1.78 (1.04–3.13)
Soluble dietary fiber in beans (g/day)	0.77 (0.48–1.18)	0.64 (0.19–0.76)	0.86 (0.59–1.20)	1.13 (0.69–2.31)
Insoluble dietary fiber in beans (g/day)	0.36 (0.18–0.63)	0.21 (0.09–0.39)	0.38 (0.22–0.60)	0.59 (0.30–1.03)

Data presented as median (quartile1- quartile3) (continuous variables).

Table 3. Adjusted hazard ratio (OR) and 95% confidence interval (CI) for the association between dietary fibre intake and the risk of poor sleep quality.

Variables	Good sleep quality	Poor sleep quality	Model 1^a	Model 2^b	Model 3^c
	(N = 280)	(N = 461)
All sources
Total dietary fiber (g/day)
T1 (<11.52)	83	164	1.00 (Ref)	1.00 (Ref)	1.00 (Ref)
T2 (11.52 to <16.86)	99	148	0.78 (0.54–1.13)	0.65 (0.43–0.98)	0.65 (0.43–0.98)
T3 (≥16.86)	98	149	0.76 (0.53–1.10)	0.52 (0.31–0.86)	0.51 (0.31–0.85)
P for trend			0.17	0.01	0.01
Total soluble dietary fiber (g/day)
T1 (<3.64)	89	157	1.00 (Ref)	1.00 (Ref)	1.00 (Ref)
T2 (3.64 to <5.93)	94	153	0.94 (0.65–1.36)	0.87 (0.59–1.29)	0.86 (0.58–1.28)
T3 (≥5.93)	97	151	0.88 (0.61–1.27)	0.72 (0.45–1.16)	0.70 (0.43–1.14)
P for trend			0.51	0.18	0.15
Total insoluble dietary fiber (g/day)
T1 (<7.68)	87	159	1.00 (Ref)	1.00 (Ref)	1.00 (Ref)
T2 (7.68 to <11.20)	91	156	0.94 (0.65–1.36)	0.79 (0.52–1.19)	0.79 (0.52–1.19)
T3 (≥11.20)	102	146	0.78 (0.54–1.13)	0.54 (0.33–0.89)	0.54 (0.33–0.89)
P for trend			0.18	0.01	0.01
Vegetables sources
Total dietary fiber in vegetables (g/day)
T1 (<2.57)	82	164	1.00 (Ref)	1.00 (Ref)	1.00 (Ref)
T2 (2.57 to <4.48)	105	142	0.68 (0.47–0.98)	0.67 (0.46–0.98)	0.65 (0.44–0.95)
T3 (≥4.48)	93	155	0.83 (0.57–1.21)	0.76 (0.50–1.14)	0.72 (0.47–1.09)
P for trend			0.48	0.25	0.18
Soluble dietary fiber in vegetables(g/day)
T1 (<1.00)	79	167	1.00 (Ref)	1.00 (Ref)	1.00 (Ref)
T2 (1.00 to <1.87)	103	144	0.66 (0.46–0.96)	0.65 (0.44–0.95)	0.62 (0.42–0.91)
T3 (≥1.87)	98	150	0.73 (0.50–1.05)	0.65 (0.43–0.98)	0.61 (0.40–0.93)
P for trend			0.16	0.07	0.04
Insoluble dietary fiber in vegetables(g/day)
T1 (<1.54)	85	161	1.00 (Ref)	1.00 (Ref)	1.00 (Ref)
T2 (1.54 to <2.61)	105	142	0.73 (0.50–1.05)	0.72 (0.49–1.05)	0.69 (0.47–1.02)
T3 (≥2.61)	90	158	0.91 (0.63–1.32)	0.83 (0.55–1.24)	0.79 (0.52–1.20)
P for trend			0.80	0.47	0.38
Fruits sources
Total dietary fiber in fruits (g/day)
T1 (<1.81)	96	150	1.00 (Ref)	1.00 (Ref)	1.00 (Ref)
T2 (1.81 to <4.07)	89	158	1.15 (0.80–1.66)	1.11 (0.75–1.63)	1.10 (0.75–1.62)
T3 (≥4.07)	95	153	1.06 (0.73–1.52)	1.01 (0.68–1.50)	1.01 (0.68–1.51)
P for trend			0.89	0.93	0.95
Soluble dietary fiber in fruits (g/day)
T1 (<0.50)	102	144	1.00 (Ref)	1.00 (Ref)	1.00 (Ref)
T2 (0.50 to <1.13)	89	158	1.25 (0.87–1.81)	1.25 (0.85–1.82)	1.24 (0.84–1.81)
T3 (≥1.13)	89	159	1.30 (0.90–1.87)	1.30 (0.88–1.93)	1.30 (0.88–1.94)
P for trend			0.21	0.25	0.24
Insoluble dietary fiber in fruits (g/day)
T1 (<1.26)	97	149	1.00 (Ref)	1.00 (Ref)	1.00 (Ref)
T2 (1.26 to <2.96)	88	159	1.17 (0.81–1.70)	1.13 (0.77–1.66)	1.13 (0.77–1.66)
T3 (≥2.96)	95	153	1.07 (0.74–1.54)	1.00 (0.68–1.50)	1.01 (0.68–1.50)
P for trend			0.87	0.89	0.91
Cereal sources
Total dietary fiber in cereals (g/day)
T1 (<2.59)	89	157	1.00 (Ref)	1.00 (Ref)	1.00 (Ref)
T2 (2.59 to <4.15)	94	153	0.91 (0.63–1.32)	0.83 (0.56–1.23)	0.83 (0.56–1.23)
T3 (≥4.15)	97	151	0.85 (0.59–1.23)	0.71 (0.45–1.11)	0.71 (0.45–1.11)
P for trend			0.40	0.14	0.14
Soluble dietary fiber in cereals (g/day)
T1 (<0.08)	90	143	1.00 (Ref)	1.00 (Ref)	1.00 (Ref)
T2 (0.08 to <0.46)	77	141	1.23 (0.83–1.82)	1.25 (0.84–1.86)	1.25 (0.84–1.86)
T3 (≥0.46)	113	177	1.00 (0.70–1.43)	0.97 (0.66–1.40)	0.96 (0.66–1.40)
P for trend			0.70	0.57	0.56
Insoluble dietary fiber in cereals (g/day)
T1 (<2.26)	86	160	1.00 (Ref)	1.00 (Ref)	1.00 (Ref)
T2 (2.26 to <3.50)	97	150	0.80 (0.55–1.16)	0.73 (0.49–1.08)	0.73 (0.49–1.08)
T3 (≥3.50)	97	151	0.82 (0.57–1.19)	0.66 (0.42–1.03)	0.66 (0.42–1.03)
P for trend			0.35	0.09	0.09
Beans sources
Total dietary fiber in beans (g/day)
T1 (<0.82)	85	160	1.00 (Ref)	1.00 (Ref)	1.00 (Ref)
T2 (0.82 to <1.54)	102	146	0.76 (0.52–1.10)	0.76 (0.52–1.11)	0.75 (0.51–1.10)
T3 (≥1.54)	93	155	0.90 (0.62–1.30)	0.84 (0.56–1.25)	0.81 (0.53–1.22)
P for trend			0.76	0.51	0.41
Soluble dietary fiber in beans (g/day)
T1 (<0.64)	86	156	1.00 (Ref)	1.00 (Ref)	1.00 (Ref)
T2 (0.64 to <1.07)	96	155	0.90 (0.62–1.30)	0.90 (0.62–1.31)	0.88 (0.60–1.29)
T3 (≥1.07)	98	150	0.86 (0.59–1.24)	0.79 (0.53–1.17)	0.75 (0.49–1.14)
P for trend			0.42	0.24	0.17
Insoluble dietary fiber in beans (g/day)
T1 (<0.22)	75	155	1.00 (Ref)	1.00 (Ref)	1.00 (Ref)
T2 (0.22 to <0.54)	109	154	0.68 (0.47–0.98)	0.68 (0.46–0.99)	0.67 (0.45–0.98)
T3 (≥0.54)	96	152	0.78 (0.53–1.14)	0.74 (0.49–1.10)	0.71 (0.47–1.08)
P for trend			0.35	0.24	0.18

CI: confidence interval; OR: odds ratio; T: tertiles; Ref: reference.

^aModel 1: adjusted for gender, age and time on dialysis.

^bModel 2: adjusted for gender, age time on dialysis, body mass index, physical activity, smoking status, drinking consumption, household income, education level, comorbidities, albumin, spKt/V, creatinine, C-reactive protein and total energy intake.

^cModel 3: adjusted for gender, age time on dialysis, body mass index, physical activity, smoking status, drinking consumption, household income, education level, comorbidities, albumin, spKt/V, creatinine, C-reactive protein, total energy and protein intake.

Table 4. Stratified analyses for adjusted hazard ratio (OR) and 95% confidence interval (CI) for the association between dietary fibre intake and the risk of poor sleep quality.

Characteristics	Tertiles of dietary fiber intake
	Total dietary fiber (g/day)				Total soluble dietary fiber (g/day)				Total insoluble dietary fiber (g/day)
	T1	T2	T3	Pinteraction	T1	T2	T3	Pinteraction	T1	T2	T3	Pinteraction
Age (years)				0.43				0.88				0.30
≤ 60	1.00 (Ref)	0.81 (0.44–1.47)	0.44 (0.20–0.94)		1.00 (Ref)	1.19 (0.67–2.10)	0.79 (0.39–1.58)		1.00 (Ref)	0.86 (0.47–1.57)	0.47 (0.22–1.00)
> 60	1.00 (Ref)	0.59 (0.32–1.07)	0.60 (0.29–1.27)		1.00 (Ref)	0.72 (0.40–1.28)	0.60 (0.29–1.21)		1.00 (Ref)	0.82 (0.45–1.51)	0.64 (0.31–1.30)
Sex				0.37				0.32				0.39
Male	1.00 (Ref)	0.80 (0.48–1.34)	0.64 (0.33–1.24)		1.00 (Ref)	1.13 (0.68–1.87)	0.97 (0.52–1.80)		1.00 (Ref)	0.96 (0.57–1.63)	0.59 (0.31–1.10)
Female	1.00 (Ref)	0.60 (0.29–1.25)	0.41 (0.17–0.98)		1.00 (Ref)	0.68 (0.33–1.41)	0.50 (0.21–1.12)		1.00 (Ref)	0.64 (0.30–1.34)	0.48 (0.19–1.15)
Diabetes				0.99				0.88				0.93
yes	1.00 (Ref)	0.94 (0.49–1.80)	0.53 (0.23–1.21)		1.00 (Ref)	1.15 (0.62–2.13)	0.88 (0.41–1.88)		1.00 (Ref)	0.87 (0.45–1.66)	0.50 (0.22–1.13)
no	1.00 (Ref)	0.52 (0.29–0.91)	0.49 (0.24–0.96)		1.00 (Ref)	0.75 (0.43–1.31)	0.61 (0.32–1.16)		1.00 (Ref)	0.72 (0.40–1.26)	0.53 (0.27–1.03)
CVD				0.31				0.28				0.29
yes	1.00 (Ref)	0.73 (0.43–1.23)	0.63 (0.33–1.21)		1.00 (Ref)	0.74 (0.44–1.22)	0.88 (0.48–1.63)		1.00 (Ref)	0.96 (0.56–1.62)	0.63 (0.33–1.20)
no	1.00 (Ref)	0.60 (0.29–1.24)	0.30 (0.12–0.72)		1.00 (Ref)	1.38 (0.68–2.83)	0.43 (0.18–0.98)		1.00 (Ref)	0.55 (0.26–1.15)	0.32 (0.13–0.76)
BMI (kg/m^2)				0.99				0.61				0.85
< 23	1.00 (Ref)	0.49 (0.25–0.93)	0.83 (0.37–1.86)		1.00 (Ref)	0.82 (0.43–1.56)	0.89 (0.42–1.89)		1.00 (Ref)	0.65 (0.34–1.24)	0.79 (0.36–1.74)
≥ 23	1.00 (Ref)	0.82 (0.47–1.44)	0.35 (0.17–0.70)		1.00 (Ref)	0.95 (0.55–1.61)	0.58 (0.30–1.11)		1.00 (Ref)	0.97 (0.55–1.71)	0.40 (0.20–0.78)
Time on dialysis (months)				0.53				0.55				0.56
< 24	1.00 (Ref)	0.56 (0.23–1.33)	1.12 (0.38–3.30)		1.00 (Ref)	1.41 (0.61–3.25)	0.90 (0.32–2.50)		1.00 (Ref)	0.92 (0.37–2.27)	0.69 (0.24–1.96)
≥ 24	1.00 (Ref)	0.63 (0.38–1.03)	0.37 (0.20–0.69)		1.00 (Ref)	0.78 (0.49–1.25)	0.68 (0.39–1.20)		1.00 (Ref)	0.70 (0.43–1.14)	0.44 (0.24–0.79)
DPI (g/kg/d)				0.96				0.87				0.73
< 1.2	1.00 (Ref)	0.62 (0.40–0.97)	0.35 (0.19–0.63)		1.00 (Ref)	0.82 (0.54–1.26)	0.56 (0.32–0.95)		1.00 (Ref)	0.79 (0.50–1.25)	0.40 (0.23–0.70)
≥ 1.2	1.00 (Ref)	0.54 (0.07–3.35)	0.99 (0.14–6.03)		1.00 (Ref)	1.69 (0.33–8.39)	1.53 (0.33–6.73)		1.00 (Ref)	0.67 (0.08–4.24)	1.08 (0.12–6.89)
DEI (kcal/kg/d)				0.93				0.88				0.68
< 30	1.00 (Ref)	0.69 (0.44–1.06)	0.45 (0.26–0.78)		1.00 (Ref)	0.87 (0.57–1.32)	0.72 (0.42–1.21)		1.00 (Ref)	0.84 (0.54–1.30)	0.50 (0.30–0.82)
≥ 30	1.00 (Ref)	0.02 (<0.01–0.35)	0.08 (<0.01–1.21)		1.00 (Ref)	0.32 (0.04–1.94)	0.31 (0.04–1.62)		1.00 (Ref)	0.14 (<0.05–1.50)	0.37 (0.01–3.95)

DPI: dietary protein intake; DEI: dietary energy intake; T: tertiles; Ref: reference.

Adjusted for gender, age time on dialysis, body mass index, physical activity, smoking status, drinking consumption, household income, education level, diabetes, hypertension, cardiovascular diseases, albumin, spKt/V, creatinine, C-reactive protein, total energy and protein intake.

Figure 2. The dose-response curve of the relationship between total dietary fiber (A), total soluble dietary fiber (B), and total insoluble dietary fiber (C) consumption and poor sleep quality. The red line and shaded area represent the estimated ORs and the 95% confidence intervals. The black horizontal short, dashed line represents reference line y = 1.

Figure 3. The dose-response curve of the relationship between total dietary fiber in vegetables (A), soluble dietary fiber in vegetables (B), and insoluble dietary fiber in vegetables (C) consumption and poor sleep quality. The red line and shaded area represent the estimated ORs and the 95% confidence intervals. The black horizontal short, dashed line represents reference line y = 1.

Figure 4. The dose-response curve of the relationship between total dietary fiber in fruits (A), soluble dietary fiber in fruits (B), and insoluble dietary fiber in fruits (C) consumption and poor sleep quality. The red line and shaded area represent the estimated ORs and the 95% confidence intervals. The black horizontal short, dashed line represents reference line y = 1.

Figure 5. The dose-response curve of the relationship between total dietary fiber in cereals (A), soluble dietary fiber in cereals (B), and insoluble dietary fiber in cereals (C) consumption and poor sleep quality. The red line and shaded area represent the estimated ORs and the 95% confidence intervals. The black horizontal short, dashed line represents reference line y = 1.

Figure 6. The dose-response curve of the relationship between total dietary fiber in beans (A), soluble dietary fiber in beans (B), and insoluble dietary fiber in beans (C) consumption and poor sleep quality. The red line and shaded area represent the estimated ORs and the 95% confidence intervals. The black horizontal short, dashed line represents reference line y = 1.

Data availability statement

The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.