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Changes in gut microbiota in response to a plant-based diet are related to changes in weight, body composition and insulin sensitivity: A 16-week randomized clinical trial. Hana Kahleova1, Emilie Rembert1, Jihad Alwarith,1 Willy Yonas,1 Andrea Tura,2 Richard Holubkov,3 and Neal Barnard1,4
1. Physicians Committee for Responsible Medicine, Washington DC, USA • 2. Metabolic Unit, CNR Institute of Neuroscience, Padua, Italy • 3. School of Medicine, University of Utah, Salt Lake City, UT, USA • 4. Adjunct faculty, George Washington University School of Medicine and Health Sciences, Washington, DC, USA.
Participants (n=148) were randomized to follow a low-fat vegan diet (n=73) or to make no diet changes (n=75) for 16 weeks.
Gut microbiota composition was assessed, using uBiome kits.
Dual energy X-ray absorptiometry was used to measure body composition.
PREDIM index was used to assess insulin sensitivity.
Repeated measure ANOVA was used for statistical analysis.
Background Gut microbiota play an important role in weight management and metabolic health
A plant-based diet may significantly change the gut microbiome composition
The aim of this study was to test the effect of a 16-week plant-based dietary intervention on gut microbiota composition, body weight, body composition, and insulin sensitivity in overweight adults with no history of diabetes.
Methods
Baseline characteristics of the Study Population Data are means ± SD, or number (%). P-values refer to t-tests for continuous variables and χ2 for categorical variables.
Body weight
C
V***
-5.8 kg (12.8 lb)
ns
***
80828486889092949698
100
0 16W
eig
ht
(kg
)Week
Fat mass
C
V***
-3.9 kg
ns
***
30
32
34
36
38
40
42
44
46
0 16
Fat
mas
s (k
g)
Week
Visceral Fat
**
-172 cm3
C
V
ns
***
10001100120013001400150016001700180019002000
0 16
Vis
cera
l fa
t (c
m3)
Week
Insulin sensitivity
C
V
ns
******
+0.9 (+0.5 to +1.2)
1.6
2.1
2.6
3.1
3.6
4.1
4.6
5.1
5.6
0 16
PR
ED
IM (
mg
/min
/kg
)
Week
CV
ns
*
20
25
30
35
40
45
0 16
Bac
tero
idet
es (
%)
Week
BacteroidetesFirmicutes: Bacteroidetes
CV
ns
ns
0
1
2
3
4
5
6
0 16
Fir
mic
ute
s:
Bac
tero
ides
Week
Faecalibacterium prausnitzii
C
V
*
****
+4.8 (+2.0 to +7.6)
1.62.63.64.65.66.67.68.69.6
10.611.6
0 16
Fa
ec
aliu
m p
rau
sn
itzi
i (%
)
Week
Bacteroides fragilisC
V
***
***
***
+19.5 (+14.7 to +24.3)
0
5
10
15
20
25
30
35
0 16
Bac
tero
ides
fra
gil
is (
%)
Week
Body weight was reduced significantly in the vegan group (treatment effect -5.8 kg [95% CI, -6.9 to -4.7 kg]; p<0.001), particularly due to a reduction in fat mass (treatment effect -3.9 kg [95% CI, -4.6 to -3.1 kg]; p<0.001) and in visceral fat (treatment effect -172 cm3 [95% CI, -308 to -37 kg]; p=0.01). PREDIM increased significantly (p<0.001) in the vegan group (treatment effect +0.88 [95% CI, +0.5 to +1.2]; p<0.001). The relative abundance of Faecalibacterium prausnitzii increased in the vegan group (treatment effect +4.8% [95% CI, +1.97 to +7.58%]; p=0.001). Relative changes in Faecalibacterium prausnitzii correlated negatively with changes in body weight (r=-0.26; p=0.008), fat mass (r=-0.26; p=0.008), and visceral fat (r=-0.25; p=0.01). The relative abundance of Bacteoides fragilis increased in the vegan group (treatment effect +19.5% [95% CI, +14.7 to +24.3%]; p<0.001). Relative changes in Bacteroides Fragilis correlated negatively with changes in body weight (r=-0.48; p<0.001), fat mass (r=-0.48; p<0.001), visceral fat (r=-0.24; p=0.02), and positively with changes in PREDIM (r=0.36; p=0.0004).
Results
ConclusionsA 16-week low-fat vegan dietary intervention induced changes in gut microbiota that were related to changes in weight, body composition and insulin sensitivity in overweight adults.
Conclusions Trial registration: ClinicalTrials.gov number, NCT02939638
Funding: This work was funded by the Physicians Committee for Responsible Medicine.
Characteristic Vegan group (n=73) Control group (n=74) Statistic
Age (years) 53.6 ± 12.1 57.6 ± 10.3 P=0.027
Sex (number, %) Male 13 (17.8) 7 (9.5) P=0.14
Female 60 (82.2) 67 (90.5)
BMI (kg/m2) 32.6 ± 3.8 33.4 ± 3.6 P=0.31
Race, (number, %) White 36 (49.3) 39 (52.7) P=0.34
Black 36 (49.3) 31 (41.9)
Asian, Pacific Islander 0 2 (2.7)
N/A - did not disclose 1 (1.4) 2 (2.7)
Figure 2. Correlations between changes in relative abundance of gut bacteria and changes in metabolic outcomes: Correlations between changes in relative abundance of Faecalibacterium prausnitzii and changes in body weight (A), fat mass (B), and visceral fat (C); and correlations between changes in relative abundance of Bacteroides fragilis and changes in body weight (D), fat mass (E), visceral fat (F), and insulin sensitivity (G).
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