25-30 Caucasian obese children will be enrolled at the Pediatric Department of San Paolo Hospital - University of Milan.
Stool samples from all enrolled patients at the different time points (t0, before supplementation and diet-lifestyle intervention, t1, four months after supplementation and diet-lifestyle intervention and t2 four months after the end of supplementation and after the alone diet-lifestyle intervention) will be collected and stored at -80°C until the following investigation:
1. study of the microbiota biodiversity by high-throughput sequencing techniques (16S rRNA gene sequencing) in order to establish whether postbiotics could modulate the microbial composition in obese children;
2. analysis of short chain fatty acids concentration by gas-chromatography (GC-FID) in order to monitor the effect of postbiotics intake modulating microbial metabolite production.
The following tasks will be also performed at t0, t1 and t2:
* Clinical examination including: physical examination, Tanner score evaluation; Bristol Stool Chart
* Blood pressure will be checked in all children by using oscillometric devices validated in the pediatric age group.
* Anthropometry including body circumferences and skinfolds, calculation of BMI z scores and body composition. Body composition will be assessed using an air displacement plethysmography system (BOD POD COSMED-USA).
* Dietary assessment:
1. Food intakes will be recorded by prospective 3-d weighed food records obtained with food scales. Parents will be advised on how to record all food and beverages consumed during 2 weekdays and 1 weekend day. Quantification and analysis of the energy intake and nutrient composition will be performed with an ad hoc PC software (MètaDieta®, Me.Te.Da S.r.l., San Benedetto del Tronto, Italy).
2. Mediterranean Diet Quality Index (KIDMED) questionnaire for Mediterranean Diet assessment. The KIDMED index ranges from 0 to 12, and is based on a 16-question test that can be self-administered. The sums of the values from the administered test will be classified into three levels:
1. 8 or more: optimal Mediterranean diet;
2. 4-7: improvement needed to adjust intake to Mediterranean patterns.
3. 3 or less: very low diet quality.
* Hematological and biochemical status including:
1. Complete cell blood count;
2. Metabolic and nutritional parameters according to local routines for childhood obesity (fasting glucose, fasting insulin, LDL, HDL, total cholesterol, triglycerides, Apolipoprotein A and Apolipoprotein B levels, transaminases and amma-glutamyl transferase). Oral Glucose Tolerance Test (OGTT) will be performed. The insulin sensitivity and insulin resistance was assessed by calculating HOMA index (Homeostasis Model Assessment) and QUICKI (Quantitative Insulin-Sensitivity Check Index), using the following formulas:
* HOMA: fasting plasma insulin in mU/l x FPG in mmol/l/22.5
* QUICKI: 1/(log10 fasting plasma insulin in mU/l + log10 glucose in mg/dl)
3. Inflammatory index (VES, high-sensitive CRP, including fecal calprotectin)
* Liver ultrasonography will be performed by a single evaluator.
All participants will follow a behavior (promotion of physical activity) and dietary treatment according to Italian dietary guidelines for childhood obesity.
Postbiotics will be given at the dose of 80 mg/day (2 ml per day SMART D3 MATRIX Smartfarma S.r.l. Via San Vittore 40 - 20123 MILAN; fermented fructooligosaccharides from Lactobacillus paracasei strain CNCM I-5220). 2 mk of product will give 1600 UI/die of VIT D3.
