Its health is closely linked not only to the skin microbiome, but also to the gut microbiome, forming what is often called the gut–skin axis. The gut microbiota influences skin health through metabolic, immune, and endocrine pathways.

Mechanisms include:

• Immune modulation: Short-chain fatty acids (e.g., butyrate, acetate) regulate systemic inflammation and T-cell responses, influencing skin conditions.
• Barrier function: A healthy gut reduces intestinal permeability (“leaky gut”), which prevents systemic inflammation that can exacerbate skin diseases.
• Neuroendocrine signaling: Microbes produce neurotransmitters (e.g., GABA, serotonin precursors) that affect the stress response and, indirectly, skin inflammation.
• Metabolites & vitamins: Gut microbes synthesize B vitamins, vitamin K, and bioactive metabolites that support skin repair and barrier function.

The gut–skin axis highlights the interplay between gut microbiota, systemic immunity, and the skin microbiome. The gut dysbiosis could induce clinical implications such as acne, atopic dermatitis, psioriasis. Microbial metabolites, especially short chain fatty acids and antioxidants may protect against oxidative stress and promote collagen synthesis that is important in skin aging.

Oral supplementation with probiotics may affect the gut dysbiosis and result in reducing inflammation, supporting barrier function, and modulating immune responses relevant to skin disorders.