Lactose intolerance is a chronic disease caused by the total/partial lack of lactase production. When lactose is not properly digest, it is consumed by the microbiota. This situation presents different gastrointestinal symptoms such as meteorism, pain, bloating, diarrhoea and nausea. The dietetic treatment for this patients consists of avoiding lactose-rich foods, mainly milk and dairy products. However, nowadays exists a large diversity of lactose-free products specially focused on lactose intolerants. In this context, using B.coagulans as a probiotic in a food matrix could be an alternative for these patients, since its ability of spore forming and the production of beta-galactosidase.

Based on the foregoing, the group research has design a randomized, double-blind, placebo-controlled crossover nutritional clinical trial to evaluate the effect of a regular probiotic with high production of beta-galactosidase effect over gastrointestinal syntoms of patients with lactose intolerance.

Probiotics are defined by Food and Agriculture Organization of the United Nations and World Health Organization (FAO/WHO) as "living microorganisms that, properly administrated, confers a benefit on individual's health". Probiotics definition it's closely related to functional food concept, which encompasses either products or ingredients that are able to exert a positive impact on individual's health beyond their nutritional value. In fact, most of consumers in developed countries, strongly associate probiotics as functional foods. Lactic acid bacteria are the main microorganisms used as a probiotic, being Lactobacillus, Bifidobacterium, Propionibacterium and Streptococcus genus the most applied. Additionally, some Saccharomyces yeast may be used as probiotics.

However, a microorganism should present particular characteristic in human gastrointestinal's tract to be considered as a probiotic, following the Joint FAO/WHO Group directions: resistance to gastric and pancreatic secretions; adherence to intestinal epithelium and mucosa; antimicrobial activity against pathogenic bacteria; capability of reducing pathogen adhesion on intestinal epithelium; and present certain enzyme activity. The former bacteria genus fulfill most of the previous characteristics. However, these microorganism survival on gut is quite low (1-15%). For this reason, recent Works are searching for microorganism genus able to survive in a larger extend in gut.

Non-pathogenic bacteria of Bacillus genus have spore forming ability in the gastrointestinal tract. Specifically, Bacillus coagulans strain has been subject of new studies. B. coagulans has an optimal growth temperature of 35-50ºC, with pH conditions nearby 6. This microorganism consumes glucose, sucrose, maltose and mannitol while growing to produce lactic acid. In addition, B.coagulans is able to produce some enzymes (depending on the strain) such as alpha and beta-galactosidase, alpha-amylase, lipase and protease. However, the capability of growing in gut depends on time from its consumption (mostly oral) and the spore generation rate. The optimal dose is about 9,52x10e11 UFC, if an standard adult of 70 Kg is assumed. In addition, several studies have proved the B.coagulans ability of forming spores in presence of energy sources such as fructose and lactose.

Lactose intolerance is a chronic disease caused by the total/partial lack of lactase production. When lactose is not properly digest, it is consumed by the microbiota. This situation presents different gastrointestinal symptoms such as meteorism, pain, bloating, diarrhoea and nausea. The dietetic treatment for this patients consists of avoiding lactose-rich foods, mainly milk and dairy products. However, nowadays exists a large diversity of lactose-free products specially focused on lactose intolerants. In this context, using B.coagulans as a probiotic in a food matrix could be an alternative for these patients, since its ability of spore forming and the production of beta-galactosidase.

Based on the foregoing, the group research has designed a randomized, double-blind, placebo-controlled crossover nutritional clinical trial to evaluate the effect of a regular probiotic with high production of beta-galactosidase effect over gastrointestinal syntoms of patients with lactose intolerance.

Inclusion Criteria:

• Men and women at 18-65 years of age
• Body Mass Index (BMI) ≥18,5 and <35 kg/m2
• Patients with lactose intolerance
• Patients with a social environment that do not prevent the clinical trial fulfillment
• Patients with proper cultural level and good understanding level about the clinical trial
• Patients that have voluntarily agreed to participate in the clinical trial, giving the written informed consent.

Exclusion Criteria:

• Patients with Body Mass Index (BMI) <18,5 or ≥35 kg/m2
• Patients with Diabetes Mellitus type 1 (DMI) or Diabetes Mellitus type 2 (DMII) with no treatment
• Patients diagnosed with metabolic syndrome
• Patients diagnosed with hyperthyroidism/hypothyroidism with no treatment
• Patients with eating disorders
• Patients with diagnosed mental disorder (dementia, any cognitive function decline)
• Patients with celiac disease
• Patients with uncontrolled high blood pressure (last 2 months)
• Patients with serious disease (ascites, cirrhosis, kidney failure, heart failure, pseudomembranous colitis, lung failure, cancer, etc.)
• Patients with chronic inflammatory bowel disease (gastritis, ulcerative colitis, irritable bowel syndrome, Crohn disease, bowel perforation, etc.)
• Patients with glomerular filtration rate <90 ml/min/1,73 m2
• Patients with auto-immune diseases
• Patients undergoing corticosteroids or immunosuppressive treatment (last 12 months)
• Patients with recent episodes of nausea, vomits or diarrhoea (last 2 weeks)
• Patients with major surgery (last 3 months)
• Patients with gastrointestinal surgery (last 6 months)
• Patients with surgery for weight loss (gastric bypass, lap band)
• Patients on anticoagulation therapy
• Patients with diagnosed lactase congenital deficit
• Patients with fructose intolerance
• Patients with allergies to cow's milk protein
• Patients with intolerance to any of the ingredients of the clinical trial products.
• Patients with excessive exercise (>2h, thrice per week)
• Patients undergoing antibiotic treatment (last month)
• Patients with high consume of supplements (antioxidants, omega-3, vitamins, minerals, prebiotics) (last 2 weeks)
• Patients with regular consumption of fermented foods (≥3 times per week, such as yogurt, kefir, blue cheese) or probiotics.
• Patients with alcoholic consumptions > 30 g/d (i.e. 300 mL of wine, 3 bottles of beer, a cup of whiskey (75 mL) or similar distilled alcoholic beverages)
• Patients with regular use of laxatives (>2 per week)
• Patients participating in more clinical trials at the same time.
• Pregnant/breastfeeding women
• Women with regular use of contraception treatment