The goal of this clinical trials is to test the impact of probiotics on skin hydration in adolescents and young adults with mild acne. The hypothesis of this study is that the probiotic formulation is superior to placebo in improving the skin hydration in adolescents and young adults with minimal acne after 12 weeks of consumption.

This pilot study is a monocentric, randomized, double-blind, placebo-controlled, parallel-arm study. The product allocation will be performed using a dynamic randomization algorithm designed to minimize imbalance between the 2 arms, within the strata defined by 3 factors: age, Global Acne Evaluation (GEA) score and sex.

60 participants (adolescents and adults) with mild acne vulgaris will be recruited for this study, according to the following inclusion and exclusion criteria.

There will be a total of 3 study visits: V1 (screening and randomization), V2 (mid-study follow-up), and V3 (end-of-study). The study will last a total of 12 weeks.

Inclusion Criteria:

1. Age between 15 and 26 years (limits included),
2. Suffering from mild acne vulgaris for at least 1 year (GEA score 1 or 2),
3. For women (adolescents and adults) who have started their sexual life: be menstruated and with the same reliable contraception method since at least six months before the beginning of the study and agreeing to keep it during the entire duration of the study. Following contraception methods are allowed: hormonal contraception, intra uterine device, surgical intervention, condoms with spermicides. Contraceptive implants (e.g. Nexplanon®) are not allowed. For women who have not started their sexual life yet, who do not intend to start their sexual life, who do not use a contraception: be menstruated and keep the habits unchanged;
4. For women (adolescents and adults): negative urine pregnancy test result;
5. Good general and mental health within the opinion of the investigator: no clinically significant and relevant abnormalities of medical history or physical examination;
6. Agree to maintain the same skin care regimen throughout the study;
7. Able and willing to participate in the study by complying with the protocol procedures, as evidenced by their dated and signed informed consent form. For adolescents (15-17 years): informed consent form signed by the guardians/parents and the individual willing to participate;
8. Affiliated with a social security scheme. For adolescents: affiliated with the social security scheme of the guardians/parents;
9. Agreeing to be registered on the national file of volunteers in biomedical research file.

After 1 month following to the non-inclusion of the participant for failure to comply with one or more of the inclusion criteria listed above, a re-screening could be performed.

Exclusion Criteria:

1. GEA score <1 or > 2 (corresponding to the absence of acne or a moderate, severe or very severe acne vulgaris),
2. Any disease that affects the secretion of sex hormones,
3. Any other dermatological disease (psoriasis, atopic dermatitis, allergy, eczema, etc.);
4. Suffering from a metabolic disorder (diabetes, uncontrolled thyroidal condition, uncontrolled arterial hypertension, etc.) and/or from severe chronic disease (cancer, renal failure, HIV, immunodeficiency, hepatic or biliary disorders, arthritis, uncontrolled cardiac disease, etc.) or from a disease found to be inconsistent with the conduct of the study by the investigator;
5. Immunodeficiency (immunodeficient and immunocompromised participants, e.g. cancer, HIV, lymphoma, participants on long-term corticosteroid treatment, chemotherapy, and allograft participants);
6. Positive COVID-test results within the last 2 weeks and/or currently showing symptoms of COVID-19;
7. Use of any systemic antibiotic or oral zinc treatment within 4 weeks prior to randomization, or isotretinoin within 3 months prior to randomization.
8. Regular consumption of probiotics, fiber supplements, fermented milk, and/or yogurt containing probiotics within 2 weeks prior to randomization and agreeing not to consume this type of product during the whole study;
9. Use of hormone replacement therapy (including oral contraceptives) for less than 6 months;
10. Under treatment or dietary supplement which could significantly affect skin microbiota according to the investigator or stopped in a too short period before V1;
11. Use of topically applied products (including topical acne drug) that could modulate potential skin improvement within 4 weeks prior to randomization. This includes products with a pH ≥ 8 such as hormone treatments, retinoid and other skin cleansing products, Micellar waters pH ≤ 5 can be used without rubbing the skin too hard with a cotton wool pad in order not to induce a Köbner phenomenon (appearance of new acne lesions on healthy but traumatised skin);
12. UVA or UVB exposure in the last 4 weeks or expected exposure during the study (short daily sun exposure is acceptable). The use of a UVA and UVB protection sunscreen factor 50 is mandatory during the study to protect against UVs;
13. With a known or suspected food allergy or intolerance or hypersensitivity to ingredient of the study products (yeast);
14. Pregnant or lactating women or intending to become pregnant within 3 months ahead;
15. With significant change in dietary or physical activity habits in the 3 months before randomization and not agreeing to keep them unchanged throughout the study (hyper or hypocaloric diet, planned start or stop of sports activity in the next 3 months);
16. With a personal history of anorexia nervosa, bulimia, or significant eating disorders within 3 years prior to randomization;
17. Consuming more than 2 standard drinks daily of alcoholic beverages or not willing to maintain their drinking habits unchanged throughout the study;
18. Participating in another clinical trial or in the exclusion period of a previous clinical trial, or participating in cosmetic tests with or without patch tests or consumer tests with food supplements containing probiotics;
19. Smoking more than 5 cigarettes per day;
20. For adults (age ≥ 18 years): Under legal protection (guardianship, wardship) or deprived of his/her rights following an administrative or judicial decision;
21. Presenting psychological or linguistic incapability to sign the informed consent;
22. Impossible to contact in case of emergency;
23. Having received, during the last 12 months, indemnities for clinical trial higher or equal to 4500 Euros.

After 1 month following to the non-inclusion of the participant for failure to comply with one or more of the exclusion criteria listed above, a re-screening could be performed.

After publications of the results, de-identified data will be shared with qualified researchers and scientists upon reasonable request to the sponsor including a detailed proposal of the intended use of the data, as per the Lallemand Health Solutions Inc. Policy on Clinical Trial Transparency and Data Sharing (available upon request).