In this study, 1010 cfu of Lb. gasseri BNR17 were given daily before meals for 12 weeks and effects on obesity-related factors were investigated. There were no significant differences in ratio of gender, age, and history of personal habits including smoking, drinking, medical treatment, or medication use between the placebo and BNR17 group.
SBT2055 also showed lowering effects on abdominal adiposity, body weight, and waist and hip circumferences in a randomized controlled human trial,19)
which was similar with our results. The reduction in waist circumference is meaningful because it is a useful indicator of visceral and subcutaneous fat distribution, and is strongly correlated with atherogenic lipid profiles.24
However, there were no changes in visceral or superficial fat in this study.
There were no changes in diabetic indices such as FBS or insulin. In animal experiments using db/db mouse,23)
however, we observed more remarkable results than in the present study; administration of BNR17 not only reduced FBS and 2PPBS but also improved tolerance to oral glucose.
It has been reported that obesity is accompanied by increased concentrations of serum total cholesterol.26
In many studies, reduction of serum total cholesterol or LDL-cholesterol by consumption of fermented milk containing probiotic strains was described, suggesting a hypocholesterolaemic effect.13
However, no reduction of cholesterol level was observed in the BNR17 group in this study, thus, it appears unlikely that BNR17 exerts a hypocholesterolaemic effect.
Administration of BNR17 reduced coliform bacterial counts in the feces of subjects. This result indicates that BNR17 suppresses the proliferation of harmful bacteria in the gut, confirming its probiotic activity. It was reported that Lb. plantarum
No. 14 may exert a beneficial effect on the onset of diet-induced obesity by reducing the cell size of white adipose tissues in mice.20)
They considered that the inhibition of lipid absorption is a possible mechanism for those effects. We also observed the reduction of white adipose tissue weight by the administration of BNR17 in high-fat diet-fed rats.22)
Adipose tissue serves as a metabolic buffer, sequestering fatty acids in the postprandial state, and releasing them under fasting conditions.28)
It has been reported that gut microbiota have an essential role in obesity development. The mechanisms that gut microbiota may influence which affect weight gain include regulation of energy harvest from the gut,9)
digestion of indigestible polysaccharides in diet,10)
production or activation of signaling molecules involved in host metabolism,18)
modification of gut permeability,10)
and release of hormones and inflammation.21
However, whether typical probiotics such as Lb.
, which are members of gut microbiota, exert a similar effect in the human intestine is largely unknown. In a study that determined the influence of an obesity treatment program on gut microbiota and body weight of overweight adolescents,31)
an increase in Lb.
group counts in feces was correlated with weight loss and BMI z-score reductions in the high weight loss group, suggesting the role of this bacterial group in body weight management.
Another researcher reported that high numbers of Bifidobacteria
and low numbers of Staphylococcus aureus
in infancy may provide protection against obesity development.9)
The feeding of mice with a high-fat diet led to increased serum lipopolysaccharides (LPS) levels and metabolic endo toxemia, resulting in an increase in proinflammatory cytokine concentration in various tissues.4)
Supplementation of the high-fat diet with oligofructose resulted in increased concentration of Bifidobacteria
and normalized concentration of LPS and consequently improved glucose tolerance and insulin sensitivity.10)
Supplementation with probiotic strains has the same effect as although endogenous bacteria is not completely clear,8)
however it seems that BNR17 may have a similar effect on energy metabolism and inflammation, because Lb. gasseri
is one of the major constituents of gut microbiota.
This will be the first clinical study on the slight weight-reducing effects of Lb. gasseri BNR17, a probiotic strain originating from human breast milk, and could provide a new and safe means to manage body weight. Even though this study had limitations such as a short trial period and unevaluated indices, it still suggests that BNR17 is effective in reducing body weight in obese or overweight patients.