Restoring an adequate dietary fiber intake by inulin supplementation: a pilot study showing an impact on gut microbiota and sociability in alcohol use disorder patients

Figures & data

Table 1. Baseline characteristics of study participants

	Placebo n = 21	Inulin n = 22	p
Sociodemographic characteristics
Age (y)	48.0 ± 9.0	48.4 ± 9.8	.90
Gender, n (%)			.11
Male	16 (76.2)	11 (50.0)
Female	5 (23.8)	11 (50.0)
Marital status, n (%)			.56
Couple/ married	9 (42.9)	7 (32.0)
Single	8 (38.1)	12 (52.0)
Separated/divorced	4 (19.0)	3 (16.0)
Educational level, n (%)			.73
Primary	2 (9.5)	2 (9.1)
Secondary	8 (38.1)	6 (27.3)
Superior	11 (52.4)	14 (63.6)
Clinical examination
Weight (kg)	71.5 ± 10.4	73.4 ± 14.7	.64
BMI (kg/m^2)	23.5 ± 3.5	24.4 ± 3.1	.34
MMSE score	28.8 ± 1.2	27.7 ± 2.9	.33
Smoking, n (%)	17 (81.0)	16 (72.7)	.72
Alcohol history
DSM-5 AUD score	7.9 ± 2.0	9.3 ± 1.4	.02
Age of loss of control (y)	31.6 ± 10.6	31.9 ± 12.0	.93
Number of alcohol withdrawal cures	2.6 ± 2.4	1.4 ± .80	.04
Duration of drinking habit (y)	15.7 ± 10.2	16.5 ± 11.9	.95
Alcohol consumption (g/d)	127.9 ± 59.6	152.7 ± 90.7	.54

Values are means ± standard deviation.N = 43.

p values were calculated using a T-test or Mann Whitney Wilcoxon’s test and Chi2 test or Fisher’s test for categorical variables.

AUD, Alcohol use disorders; Alcohol Use Disorders Test; BMI, Body mass index; DSM-5, Diagnostic and Statistical Manual of Mental Disorders fifth edition; MMSE, Mini Mental State Examination.

Figure 1. Flow chart of the Gut2Brain study

Figure 2. Changes in gastrointestinal symptoms after inulin supplementation in AUD patients. Values are mean ± SEM. Gastrointestinal symptoms including abdominal pain (a), bloating (b) and satisfaction of intestinal transit (c), impact of the symptoms on daily life (d), stool frequency (e), Bristol stool form scale (f) and (g) total tolerance score. Linear mixed models were performed for detecting the treatment effect throughout the study. D1 represents the baseline score before the supplementation. D3 represents the first day of inulin or placebo treatment

Figure 3. Effect of inulin supplementation on gut microbiota composition in alcohol use disorder patients. (a) Principal coordinate analysis (PCoA) of the Bray Curtis index (b) Changes in alpha-diversity indexes: Number of observed species, Chao-1 and Shannon. *p < .05, **p < .01,***p < .001 (c) Changes in total bacteria measured by qPCR. (d) Relative abundances of bacterial taxa accounting for more than 1%, at the phylum and family levels, assessed using Illumina 16S rRNA gene sequencing in AUD patients supplemented with placebo (n = 19) or inulin (n = 19). Wilcoxon paired tests were performed to compare the evolution from baseline in each group. P-values were adjusted to control for the false discovery rate for multiple testing according to the Benjamini and Hochberg procedure *q < 0.10 in inulin group, † q < 0.10 in placebo group. (e) Relative abundances of genera that were significantly change between T1 and T2 in inulin group. Wilcoxon paired tests were performed and p-values were adjusted to control for the false discovery rate for multiple testing according to the Benjamini and Hochberg procedure *q < 0.1 (f) Spearman correlation between the change in sociability score (T2-T1) and the change of Bifidobacterium levels (T2-T1) measured by qPCR in inulin group

Figure 3. Continued

Table 2. Significant changes in relative abundance of gut bacteria at the genus level in AUD patient receiving inulin or placebo for 3 weeks*

		Placebo		Inulin		p Placebo	q Placebo	p Inulin	q Inulin
		T1	T2	T1	T2
Changed in placebo	Acidaminococcus	1.059 ± 1.460	0.660 ± 1.031	0.630 ± 1.523	0.857 ± 1.854	0,039	0,203	0,418	0,617
	Lachnospiraceae ND3007 group	0.162 ± 0.154	0.210 ± 0.228	0.133 ± 0.155	0.135 ± 0.132	0,016	0,148	0,670	0,785
	Lachnospiraceae NK4A136 group	0.043 ± 0.112	0.125 ± 0.305	0.089 ± 0.259	0.124 ± 0.344	0,017	0,148	1,000	1,000
	Monoglobus	0.158 ± 0.202	0.450 ± 0.815	0.183 ± 0.241	0.157 ± 0.221	0,005	0,148	0,977	1,000
	Oscillibacter	0.344 ± 0.344	0.206 ± 0.177	0.283 ± 0.277	0.222 ± 0.196	0,049	0,218	0,077	0,268
	Escherichia Shigella	1.038 ± 2.391	0.220 ± 0.498	0.406 ± 0.825	0.464 ± 1.769	0,011	0,148	0,134	0,321
	Eubacterium siraeum group	0.351 ± 0.577	0.822 ± 1.130	0.137 ± 0.267	0.260 ± 0.524	0,026	0,148	0,754	0,850
	Sutterella	1.998 ± 1.512	1.377 ± 1.169	2.945 ± 2.086	2.086 ± 1.419	0,009	0,148	0,055	0,241
	Oscillospiraceae UCG-002	1.852 ± 2.348	2.316 ± 2.411	1.829 ± 2.166	1.291 ± 1.646	0,021	0,148	0,098	0,284
	Oscillospiraceae UCG-003	0.069 ± 0.083	0.138 ± 0.155	0.100 ± 0.106	0.061 ± 0.068	0,041	0,203	0,060	0,241
	Gordonibacter	0.056 ± 0.085	0.221 ± 0.460	0.110 ± 0.281	0.047 ± 0.075	0,025	0,148	0,295	0,495
Changed in inulin	Dorea	0.261 ± 0.228	0.212 ± 0.174	0.289 ± 0.279	0.087 ± 0.057	0,651	0,781	<0,001	0,007
	Bacteroides	20.39 ± 10.40	19.34 ± 9.77	19.83 ± 9.48	14.83 ± 10.33	0,073	0,278	0,002	0,028
	Ruminococcus torques group	0.456 ± 0.612	0.279 ± 0.330	0.255 ± 0.352	0.064 ± 0.092	0,296	0,460	0,001	0,027
	Lachnospiraceae unknown genus	0.693 ± 0.438	0.622 ± 0.348	0.787 ± 0.527	0.370 ± 0.321	0,275	0,460	<0,001	0,007
	Haemophilus	0.015 ± 0.039	0.034 ± 0.066	0.197 ± 0.792	0.601 ± 0.974	0,575	0,743	0,021	0,180
	Butyricicoccus	0.371 ± 0.243	0.460 ± 0.277	0.567 ± 0.418	0.481 ± 0.380	0,418	0,616	0,029	0,194
	Desulfovibrio	0.816 ± 1.195	0.811 ± 1.004	0.786 ± 1.233	0.552 ± 1.092	0,737	0,825	0,030	0,194
	Dialister	0.821 ± 1.976	0.434 ± 1.026	0.847 ± 1.504	2.445 ± 3.050	0,488	0,686	0,017	0,159
Opposite Changes	Bifidobacterium	5.275 ± 5.232	3.556 ± 3.263	4.300 ± 5.621	8.177 ± 4.967	0,026	0,148	<0,001	0,007
	Oscillospiraceae unknown genus	0.227 ± 0.123	0.241 ± 0.111	0.192 ± 0.114	0.151 ± 0.094	0,047	0,217	0,005	0,054
	Flavonifractor	0.259 ± 0.301	0.171 ± 0.293	0.344 ± 0.537	0.359 ± 1.060	0,019	0,148	0,029	0,194
Similar changes	Colidextribacter	0.253 ± 0.183	0.137 ± 0.132	0.244 ± 0.247	0.132 ± 0.103	0,003	0,148	0,003	0,040
	Erysipelotrichaceae UCG 003	0.985 ± 0.926	0.682 ± 0.962	0.728 ± 0.962	0.358 ± 0.560	0,026	0,148	0,011	0,118
	Lachnoclostridium	1.051 ± 0.666	0.774 ± 0.654	0.981 ± 1.162	0.791 ± 0.962	0,026	0,148	0,032	0,194

Values are means ± standard deviation *Genus significantly modified after 17 days of treatment were identified using Wilcoxon paired test. P-values were adjusted to control the false discovery rate for multiple testing according to the Benjamini and Hochberg procedure (q value).

Table 3. Effect of inulin supplementation on biological parameters

	Placebo		Inulin		Difference in change from baseline M1	Difference in change from baseline M2
	T1	T2	T1	T2	β [95% CI]	β [95% CI]
Metabolism
Glucagon (pM)	21.5 ± 11.0	17.1 ± 6.7	23.8 ± 11.2	18.9 ± 8.3	2.44 [−1.95; 6.83] p = .27	1.67 [−2.52; 5.87] p = .42
Glucose (mg/dL)	73.6 ± 8.2	71.7 ± 9.5	75.2 ± 12.1	74.0 ± 9.2	2.13 [−2.92; 7.18] p = .40	1.96 [−3.16; 7.08] p = .44
Cholesterol mmol/L	4.8 ± 0.9	4.5 ± 0.8	5.2 ± 1.1	4.6 ± 1.0	−0.14 [−0.55; 0.28] p = .50	−0.17 [−0.57; 0.24] p = .40
Triglycerides mmol/L	1.4 ± 1.2	1.1 ± 0.4	1.5 ± 1.1	1.4 ± 0.9	0.31 [−0.01; 0.63] p = .06	0.26 [−0.03; 0.56] p = .08
NEFA mmol/L	0.8 ± 0.5	0.5 ± 0.2	0.9 ± 0.5	0.7 ± 0.5	0.13 [−0.11; 0.38] p = .28	0.08 [−0.16; 0.31] p = .52
Gut Hormones/peptides
Active GLP-1 (pM)	0.69 ± 0.57	0.38 ± 0.27*	0.65 ± 0.39	0.57 ± 0.47	0.11 [−0.12;0.35] p = .34	0.12 [−0.12; 0.36] p = .31
GLP-1 (pM)	29.2 ± 15.6	23.6 ± 11.8	28.6 ± 13.6	26.0 ± 11.1	−0.34 [−6.9;6.3] p = .92	−1.58 [−7.81; 4.64] p = .61
Active Ghrelin (pg/ml)	189.1 ± 124.5	152.2 ± 73.2	206.6 ± 143.6	228.8 ± 172.1	49.0 [−16.59;114.58] p = .14	46.40 [−20.5; 113.3] p = .17
Ghrelin total (pg/ml)	594.0 ± 367.8	499.7 ± 235.1	621.3 ± 346.3	564.2 ± 333.4	14.90 [−145.3;175.1] p = .85	16.79 [−147.1; 180.71] p = .84
Leptin/BMI	544.2 ± 545.6	490.3 ± 427.9	861.4 ± 506.3	722.9 ± 476.2*	21.43 [−142.7;185.6] p = .79	2.66 [−149.8; 155.2] p = .97
PYY (pg/ml)	94.4 ± 61.6	80.2 ± 35.7	79.2 ± 32.2	71.6 ± 28.7	−5.19 [−26.8;16.4] p = .63	−7.73 [−29.07; 13.62] p = .47
Growth factors
BDNF (pg/ml)	41.29 ± 26.47	39.9 ± 17.6	44.7 ± 24.2	51.3 ± 17.8	10.32 [−2.2; 22.9] p = .10	12.72 [0.89; 24.54] 0.04

*** p < 0.001, ** p < 0.01, * p < 0.05 paired T-test or Wilcoxon test: intra-group comparison. β: regression coefficient.

M1: model 1 adjusted for gender and the parameter at baseline

M2: model 2 adjusted for gender, the parameter at baseline and the quantity of ethanol consumed during the second week of the program.

Table 4. Effect of inulin supplementation on psychological parameters

	Placebo		Inulin		Difference in change from baseline M1 β [95% CI]	Difference in change from baseline M2 β [95% CI]
	T1	T2	T1	T2
Depression
Beck depression inventory	22.0 ± 10.7	10.6 ± 9.2***	29.0 ± 12.5	18.0 ± 10.0***	2.04 [−3.19; 7.27] p = .44	1.56[−3.64; 6.75] p = .55
BDI suicide score	1.1 ± 1.0	0.5 ± 0.9	1.6 ± 1.4	0.9 ± 1.0**	0.06 [−0.49; 0.61] p = .82	0.05 [−0.53; 0.63] p = .85
BDI fatigue score	2.6 ± 1.4	1.0 ± 1.3***	3.4 ± 1.32	1.6 ± 1.6***	0.01 [−0.93; 0.94] p = .99	−0.04 [−0.99; 0.91] p = .93
Anxiety
STAI-State	46.0 ± 13.9	38.1 ± 13.5*	47.2 ± 15.9	42.4 ± 13.6*	1.18 [6.32; 8.68] p = .75	0.45 [−6.98; 7.89] p = .90
Craving
OCDS	24.3 ± 6.4	7.2 ± 6.5***	25.1 ± 5.2	9.8 ± 5.3***	2.29 [−1.55; 6.13] p = .23	1.39 [−1.69; 4.48] p = .37
OCDS OT	10.6 ± 3.74	4.4 ± 4.4***	10.6 ± 3.9	5.7 ± 3.6***	1.13 [−1.34; 3.60] p = .36	0.54 [−1.42; 2.51] p = .58
OCDS CT	13.7 ± 3.1	2.8 ± 2.3***	14.5 ± 2.4	4.0 ± 2.3***	1.10 [−0.48; 2.69] p = .17	0.76 [−0.62; 2.14] p = .27
Sociability
Social high pleasant	3.8 ± 1.5	4.2 ± 1.4	3.8 ± 1.4	4.1 ± 1.2	0.23 [−0.52; 0.99] p = .54	0.32 [−0.43; 1.08] p = .39
Social medium pleasant score	3.4 ± 1.5	3.7 ± 1.7	3.9 ± 1.3	4.4 ± 1.0*	0.68 [0.04; 1.33] p = .039	0.71 [0.07; 1.35] p = .03
Social low pleasant	3.0 ± 1.42	4.0 ± 1.3**	3.2 ± 1.5	4.0 ± 1.4***	0.17 [−0.50; 0.84] p = .60	0.23 [−0.44; 0.91] p = .49

Values are means ± standard deviation. β: regression coefficient.

M1:Linear regression model adjusted for gender and the parameter at baseline

M2: Linear regression model adjusted for gender, the parameter at baseline and the quantity of ethanol consumed during the second week of the program.

*** p < 0.001, ** p < 0.01, * p < 0.05 paired T-test or Wilcoxon test: intra-group comparison

AUD, alcohol use disorder; BDI, Beck Depression Inventory; CT: Compulsive Thoughts; OCDS, Obsessive compulsive drinking scale; OT, Obsessive Thoughts; STAI: State-trait anxiety inventory.

Figure 4. Effect of inulin supplementation on psychological parameters in Alcohol use disorder patients. (a) Score of depression measured by the Beck Depression Inventory. (b) Anxiety measured by the State-Trait Anxiety Inventory (form YA). (c) Alcohol craving (total score) measured by the Obsessive-Compulsive Drinking Scale. (d) Sociability score (social medium pleasant activity score) measure by the social activity test. Wilcoxon signed ranks tests or paired T-tests were performed to analyze changes from baseline according to the distribution *p < .05, **p < .01,***p < .001

Data availability statement

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. The accession number for the raw data generated with the 16S rRNA gene sequencing reported in this paper is BioProject PRJNA745947 (SRA) and are available here https://www.ncbi.nlm.nih.gov/bioproject/PRJNA745947/.