Probiotic skin care products are claimed to have benefits ranging from anti-aging to mood-enhancing, so researchers reviewed the scientific evidence and found that while some probiotic strains can affect mental health when ingested, there is currently no evidence that applying them to the skin affects mental well-being.
Research: Neurocosmetics or hype? The psychobiological potential of strain-specific cosmetics. Image credit: polinaloves/Shutterstock.com
The growing popularity of probiotic skin care has raised questions about ethical and safe research support. Cosmetic marketing now claims medical benefits beyond simple skin care, such as immunomodulatory and neuroactive properties. Recent articles published in journals nutrients examines these claims based on published literature.
Probiotic skin care claims
The U.S. Federal Food, Drug, and Cosmetic Act defines cosmetics as “articles intended for application to the human body for the purpose of beautifying, promoting attractiveness, or altering appearance.” This is also reflected in European regulations, which confirm that cosmetic products are intended to affect the skin or its appendages. Therefore, it is necessary to prove the safety and microbiological quality of cosmetic products. The skin is an organ that is in close contact with and interacts closely with the skin microbiome and is often referred to as the fourth layer of the skin.
The skin-brain axis has recently received a lot of attention. It is composed of multiple neurotransmitters and neurotransmitters produced by nerve endings, skin cells such as keratinocytes and melanocytes, and the skin’s immune cells. Bidirectional interactions between them result in cutaneous symptoms caused by emotional stress, neuroinflammation, and cutaneous dysbiosis, which are further influenced by the skin.
Recently, restoring the microbiome using bacteria and related products has become a popular research topic. Currently, there are cosmetic products on the market that contain probiotic bacteria in a live or non-viable state, or postbiotics, i.e. parts of cell walls or their metabolites. These are called cosmeceuticals because they contain bioactive ingredients with claimed medical effects.
According to the authors, scientifically supported cosmetic products should contain specific probiotic strains that are fully characterized genetically and phenotypically. Supported by peer-reviewed papers that explain the rationale for their use. And the administration technique, dose, and duration are supported by human studies. When used topically, they are claimed to be able to alter the composition and abundance of the skin microbiome, reducing inflammation and inhibiting signs of aging such as wrinkles, lines, and pigmentation. It is also claimed to increase skin hydration and elasticity by altering the epithelial barrier.
Additionally, some researchers claim that cosmetics may improve emotional and mental health and improve the appearance of your skin. These are called neurocosmetics. Their mood-enhancing effects are claimed to result from the release of chemicals that act on the brain via the skin-brain axis. This claim received considerable backlash from skin experts and psychiatrists who questioned whether its use was ethical and/or safe.
Probiotics that are associated with improved mental health when taken orally are called psychobiotics. They release neuroactive substances that act on the brain-gut axis, contributing to the reduction of mental disorders such as anxiety, stress, and depression. The underlying mechanisms remain unclear or poorly studied.
Interestingly, the current authors found only 14 previous studies supporting the use of cosmetic products containing probiotics or postbiotics. In contrast, a 2023 publication reported 928 patents for cosmetic products containing probiotics, most of them from the United States, China, and South Korea. As there are few well-defined studies on these claims, the current paper focuses on a targeted review of the published literature on neurocosmetics rather than a fully systematic review. The authors also emphasized strain-level specificity and noted that the effects of probiotics cannot be generalized across species or strains.
Evaluation of probiotic strains used in cosmetics
For the current study, we examined peer-reviewed publications and selected only those that featured cosmetic products containing specific, fully characterized probiotic microbial strains with established skin benefits. Next, the researchers searched existing literature for clinical or experimental evidence that these strains have psychobiological effects when administered orally rather than primarily through topical cosmetic use.
Only three probiotic strains show evidence of oral psychobiotics
Researchers identified 33 strain-specific probiotics reported in cosmetics research. Of these, we found three strains that have evidence, primarily in preclinical studies, that they have mental health benefits when taken orally. These stocks are:
Lactococcus lactis subsp. cream H61
It was one of the earliest strain-specific probiotic cosmetic ingredients studied and was reported to have psychobiological activity. Its use is supported by four papers, all by the same authors.
Limosylactobacillus reuteri DSM 17938
Oral intake L. reuteri It has been reported to improve skin and hair health in animals, and skin wounds heal twice as fast. Human trials using small samples found that it tended to reduce skin irritation, with no ultimate clinical benefit, making it acceptable for cosmetic use. Preclinical studies also suggest stress- and cognition-related effects after oral administration, but human evidence remains limited and indirect.
Wisemannia coagulans MTCC 5856
It is a spore-producing lactic acid-producing bacillus and shares characteristics of both strains mentioned above. It may help regulate the skin microbiome, improve immunity, combat metabolic disorders, alleviate non-alcoholic fatty liver disease, and reduce inflammation. It is also said to reduce acne and promote healthy skin aging. In a small study of patients with irritable bowel syndrome and depression, oral supplements improved depression scores, which may be associated with improved gastrointestinal symptoms.
For all three strains, psychobiological effects occur only when used orally and through effects on the gut-brain axis. Current evidence does not support a direct effect on the user’s emotional state when used in cosmetics.
Neurocosmetic claims still not supported by clinical evidence
At this time, there is no evidence to support the claim that topical application of cosmetics can directly influence emotional states. It is very rare for the same probiotic strain to exhibit both cosmeceutical and psychobiological properties.
Further targeted studies, perhaps incorporating combinations of probiotics to achieve this effect, are essential before neurocosmetic claims can be considered evidence-based.
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Reference magazines:
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Menni, A., Theodorou, H., Tzikos, G., et al. (2026). Neurocosmetics or hype? Psychobiological potential of strain-specific cosmetics. nutrients. Toi: https://doi.org/10.3390/nu18050817. https://www.mdpi.com/2072-6643/18/5/817
