Beneficial effects of moderate chronic consumption of beer have been extensively reported, however, the mechanisms have not been elucidated yet. Gut microbiota is an important mediator in the homeostasis of the host. Polyphenols act as bacterial substrates and modulators of the gut microbiota. Indeed, the investigators have previously observed that the chronic moderate consumption of red wine by metabolic syndrome patients triggered in an amelioration of the metabolic syndrome variables, and this effect was mediated, at least partially, by the interaction of the gut microbiota with the polyphenols of the red wine. In this manner, beer has a medium content of polyphenols. Thus, the investigators propose that the beneficial effects of moderate chronic consumption of beer could be because of the action of the gut microbiota with the beer polyphenols. The investigators are going to perform an intervention study in which normal volunteers will consume three different beer types with different content in polyphenols and it will be analyzed the gut microbiota profile (Metagenomics), metabolites (Metabolomics) and metabolic syndrome markers (gene expression, ELISA) to establish the correspondent relationships, trying to decipher the implication of the gut microbiota in the beneficial effects of moderate chronic consumption of beer.

Inclusion Criteria:

• Age > 18 years
• Usual consumer of Beer

Exclusion Criteria:

• being a non usual beer-consumer,
• body mass index (BMI) > 40 kg m2.
• acute or chronic infection, inflammatory disease or endocrine disorders; history of cancer; leukocytosis; anti-inflammatory, corticosteroid or hormone treatment.
• history of alcohol abuse or drug dependence.
• under a restrictive diet or a weight change ≥5 kg during the 3 months prior to the study.
• antibiotic therapy, prebiotics, probiotics, synbiotics, vitamin supplements or any other medical treatment influencing intestinal microbiota during the 3 months before the start of the study or during the study.