Functional fermented dairy products: a review of mechanisms, health potential, and technological challenges

Fermented dairy products such as yoghurt, kefir and cheese are increasingly recognised as functional foods due to the metabolic activity of lactic acid bacteria and the associated microbial communities, including probiotics. During dairy fermentation, these microorganisms generate bioactive compounds, such as bioactive peptides, exopolysaccharides, organic acids and other metabolites, which may contribute to host health. There is emerging evidence that fermented dairy products can influence gastrointestinal function, immune regulation, metabolic health and cardiovascular risk, via mechanisms involving modulation of the gut microbiota, stabilisation of the epithelial barrier and inflammatory signalling pathways. In addition, fermentation may improve lactose digestion, enhance nutrient bioavailability, and generate peptides with anti-hypertensive or antioxidant properties. However, translating these results into consistent health benefits is challenging due to the significant variability in microbial strains, product composition, processing conditions and dosage. Safety considerations such as biogenic amines, sodium content, allergenicity and antimicrobial resistance also require careful monitoring. Future progress in this field will depend on improved product characterisation, strain-level identification and well-designed human intervention studies that integrate multi-omics approaches. In conclusion, fermented dairy products show great potential as a source of bioactive compounds, but more robust clinical evidence and standardised methodologies are required to firmly establish their role in promoting human health.