Nutrition and microbiota in ocular surface and dry eye disease.

Nutrition plays a crucial role in the prevention and management of dry eye disease (DED. Polyunsaturated fatty acids ω-3 and ω-6, known for their anti-inflammatory properties, improve ocular surface health. Similarly, antioxidants found in diets like the Mediterranean diet stabilize the tear film and reduce oxidative stress (OXs); however, food additives can negatively impact both general health and DED. The gut microbiome and the gut-eye axis play a critical role, as gut dysbiosis amplifies systemic inflammation, disrupts immune balance, and diminishes the production of protective metabolites such as short-chain fatty acids. The ocular microbiome further supports homeostasis and immunity by safeguarding against external pathogens. Factors such as diet, aging, and antibiotic use negatively impact microbial diversity. Probiotics, prebiotics, and fecal microbiota transplantation are emerging microbiota-targeted strategies for dry eye disease. However, current evidence remains limited and is largely based on preclinical and preliminary clinical studies, highlighting the need for further controlled investigations to better define their therapeutic role and clinical applicability.