the aim of the study is to get evidence for an enhancement of immune status in subjects after probiotics mixture consumption ( lactobacillus gasseri PA 16/8, Bifidobacterrium longum SP 07/3, Bifidobacterium bifidum MF 20/5) based on influenza vaccination model - compared to placebo.

probiotics are "live microorganisms which when administered in adequate amounts confer a health benefit on the host" . many health effects are associated with probiotics , but various degrees of evidence support the benefits associated to probiotics consumption . Impact on defences and the immune system has been shown with several strains and this may result in improved protection against some infections or improvment of vaccine efficacy .

In its scientific requirments for health claims related to immune function, EFSA indicates that it is generally accepted that higher vaccination responses are beneficial.

Inclusion Criteria:

• healthy male and female adult
• between 18 and 60 years old non menopausal female( with effective contraception)
• female non pregnant- not wishing to be pregnat during the study capable to respect the protocol
• affialted to the social security system aggreeing to be registered in the national fileof volunteers

Exclusion Criteria:

• food allergy( component of the experimental product- vaccines)
• manifestation of allergy
• vaccinated against flu during the 2 previous winters
• Food allergy, allergy to one of the component of the experimental products or allergy to one of the component of the flu vaccine;
• Subject displaying manifestation of allergy or being treated for these;
• Subject vaccinated against flu during the 2 previous winter (winter 2009-2010 and winter 2010-2011);
• Subject who had symptoms evocating flu during the previous winter (winter 2010-2011);
• Subject immunodepressed;
• Subject with immunomodulatory treatment;
• Subject who received a treatment resulting in systemic immunossuppression or local immunosuppression at pulmonary level, for at least 1 week during the last 3 months before inclusion (V1);
• Subject with auto-immune disease;
• Subject with inflammatory and chronic diseases;
• Subject with on-going antibiotics treatment at the time of the inclusion;
• Subject not agree to stop his/her usual probiotics supplementation during the study;
• Use of medication which could interfere with the study in the investigator's opinion (antibiotics, etc…);
• Any health condition for which the influenza vaccine is not recommended;
• Subject having received any other vaccine within one month prior to enrolment or intent to receive any other vaccination during the study period.