Celiac disease is a disorder caused by a disregulation of the immune system which leads to immune response to gluten. Diet therapy is the gold standard of treatment, and the only effective one. Macronutrients and micronutrients deficiency (vitamin D, folic acid, vitamin B12, vitamin B6, iron and zinc), which is in any case far more common in patients who don't follow gluten free diet, can persist in a subset of patients who follow gluten-free diet. Supplementation of vitamins in these patients may have a beneficial role. A recent study in a murine model showed that supplementation with probiotic VIVOMIXX® leads to an increase in expression of vitamin D receptors in proximal and distal colon.

This is an interventional controlled randomized double blind study, which evaluates the effect of VIVOMIXX® on vitamin status.

90 patients with celiac disease who follow gluten free diet will be enrolled. INCLUSION CRITERIA

• Celiac disease (diagnosis made according to ESPGHAN criteria) EXCLUSION CRITERIA
• Supplementation with pre/probiotics in the previous 3 months;
• Antibiotic therapy in the previous 3 months;
• Comorbidity with other acute (in the previous 3 months) or chronic gastrointestinal disorders
• Supplementation with group B vitamins for any reason

Patients enrolled will be referred to Paediatric Gastroenterology Service in San Paolo Hospital at the time of enrollement (T0) and after intervention therapy (T1, + 4 months).

Patients will be randomized in one of the two arms of intervention (VIVOMIXX once a day for 4 months versus placebo once a day for 4 months).

VIVOMIXX® is a probiotic containing 8 differenct strains of bacteria: Streptococcus thermophilus DSM 24731, bifidobacteria (B. breve DSM 24732, B. longum DSM 24736, B. infantis DSM 24737) lactobacilli (L. acidophilus DSM 24735, L. plantarum DSM 24730, L. paracasei DSM 24733, L. delbrueckii subsp. bulgaricus DSM 24734). Every sachet contains 450 billions of bacteria, maltose and silicon dioxide. VIVOMIXX® will be freely given by the society MENDES S.A. - Lugano Switzerland.

At each time point clinic evaluation, nutritional assessment and blood testing will be made. Data collection will include:

• Systemic arterial blood pressure;
• Anthropometric measures (height, weight, body mass index, waist circumference, triceps skinfold)
• Clinical evaluation including presence/absence of oral aphtous stomatitis
• Measure of chinolinic acid, serotonin, ghrelin (analysis will be made at Istituto Malattie Infettive, Università La Sapienza, Roma).
• Dosing of inflammatory markers (analysis will be made at Health Sciences Department, San Paolo Hospital).
• Metabolomics on stool samples (analysis will be made at Bologna University, Dipartimento di Scienze e Tecnologie Agro-Alimentari, Cesena, with a financial fund by MENDES S.A. - Lugano Switzerland).
• Routine blood testing including complete blood cell count, vitamin B6, acid folic, vitamin B12, vitamin D 25'OH, fasting glucose, fasting insulin, total cholesterol, LDL and HDL cholesterol, Apolipoprotein A1 and Apolipoprotein B, triglycerides, homocistein, auto-antibody anti endomisium and anti-transglutaminase,
• Genetic testing for MTHFR gene
• ESR, highly sensitive CRP, IL6, TNFalfa, fibrinogen
• Fecal calprotectin.

Inclusion Criteria:

• Celiac disease (diagnosis made according to European Society for Paediatric Gastroenterology Hepatology and Nutrition)

Exclusion Criteria:

• Supplementation with pre/probiotics in the previous 3 months;
• Antibiotic therapy in the previous 3 months;
• Comorbidity with other acute (in the previous 3 months) or chronic gastrointestinal disorders
• Supplementation with group B vitamins for any reason