Food Science and Agriculture: Research Highlights Vol. 9

Natural sweeteners occupy an increasingly important position in sugar-reduction strategies, yet the category combines chemically and physiologically dissimilar ingredients whose health value and processing behaviour cannot be inferred from natural origin alone. This critical narrative review integrates evidence on plant-derived high-intensity sweeteners, rare sugars, polyols, honey and plant syrups, and sweet-tasting proteins, with emphasis on the relationship between human health evidence and food-processing functionality. Human trials and quantitative syntheses provide the clearest support for acute attenuation of postprandial glycaemic responses with D-allulose and D-tagatose, whereas longer-term effects on body composition and cardiometabolic outcomes remain less certain. Steviol glycosides may modestly reduce fasting glucose, but the certainty of evidence is low and effects on glycated haemoglobin are not established. Honey and maple syrup contain bioactive constituents and have shown favourable changes in selected cardiometabolic markers under controlled substitution conditions, but both remain concentrated sources of free sugars. For xylitol, the dental literature suggests potential anticaries value but is methodologically uneven; recent cardiovascular biomarker and mechanistic studies of xylitol and erythritol introduce safety questions that require prospective dietary studies rather than causal extrapolation from circulating concentrations. Processing performance is equally heterogeneous. High-intensity glycosides and sweet proteins provide sweetness but little bulk, while rare sugars and polyols better reproduce sucrose-related solids functionality yet alter browning, crystallisation, texture and gastrointestinal tolerance. Honey and fruit or tree syrups contribute flavour, colour and minor bioactives but complicate claims of sugar reduction. Extraction, purification, enzymatic conversion, fermentation and non-thermal preservation can improve ingredient yield or quality, although processing may also modify phenolics, sensory attributes and reaction products. The evidence therefore supports a matrix-specific, substitution-based approach in which health outcomes, sensory acceptance, technological function, dose and processing history are evaluated together. Future research should prioritise longer controlled trials, source-standardised ingredients, realistic food matrices and integrated health-processing endpoints.