Abstract
Functional foods have attracted increasing scientific and commercial interest due to their potential roles in health promotion and the prevention of non-communicable diseases such as diabetes and cardiovascular diseases. In this review, we will critically examine the current evidence on functional foods by focusing on their classification, bioactive components, biological mechanisms, consumer acceptance and regulatory frameworks. Bioactive compounds, such as polyphenols, dietary fibre and probiotics, from both plant- and animal-origin functional foods, have also been examined in this review. Despite substantial experimental and epidemiological evidence, the translation of functional foods into consistent health benefits remains challenged by variability in bioavailability, food matrix effects, processing conditions and interindividual differences in genetics and gut microbiota. Key mechanistic determinants of bioefficacy, including intestinal transport processes, molecular structure, stereochemistry, and food-drug interactions, are discussed. Consumers' perception and purchasing behaviour are examined, identifying the influence of product format, socio-demographic characteristics, information sources, health motivation and price sensitivity. Our review also compares the regulatory approaches in the United States, European Union, Japan and China, highlighting the heterogeneity in definitions and health claim substantiation requirements. Finally, emerging opportunities such as metabolic profiling technologies and personalised nutrition are highlighted as future directions to support evidence-based, effective and equitable functional food development.