Background: Alzheimer’s disease (AD) remains a major public health challenge. Observational associations between dietary patterns and reduced dementia risk have prompted investigations of dietary bioactives (DBs) as cognitive nutraceuticals. Methods: This critical narrative review examines interventional trials for nine prominent DBs relevant to AD: docosahexaenoic acid (DHA), curcumin, resveratrol, epigallocatechin gallate (EGCG), nicotinamide riboside (NR), tricaprilin, vitamin E (α-tocopherol), cannabinoids, and NIC5-15 (D-pinitol). Trials were identified through ClinicalTrials.gov (search date: December 2024) and supplemented by PubMed searches for published results. Data were extracted on trial phase, design, cognitive/functional endpoints, biomarker outcomes, and development status. Findings are synthesized qualitatively; no formal meta-analysis or risk of bias assessment was conducted. Results: None of the nine bioactives demonstrated consistent cognitive efficacy in AD. Phase III trials of DHA, curcumin, and tricaprilin did not meet primary cognitive endpoints. Resveratrol reduced CSF Aβ40 without cognitive benefit. Cannabinoids improved behavioral symptoms but showed no measurable cognitive effects. High-dose vitamin E slowed functional decline, while cognition remained unchanged. In contrast, trials in preclinical or at-risk populations reported preliminary cognitive signals for EGCG and biomarker engagement for NR, suggesting potential for early intervention. Conclusions: Current clinical evidence does not support high-dose DBs supplementation as an effective treatment for AD. Predominantly negative late-phase findings highlight limitations, with potential contributors including limited bioavailability, late intervention, insufficient target engagement, and biological heterogeneity. Future research may benefit from early biomarker-defined populations, optimized formulations, multi-nutrient or dietary approaches, and precision nutrition strategies considering genetic risk and baseline nutrient status. DBs may be better positioned for prevention or early-stage intervention rather than late-stage therapy.

Ultrasound-assisted nanoemulsification has emerged as a versatile platform for producing food-grade nanoemulsions with enhanced stability and improved delivery potential of lipophilic bioactives. This review offers a critical, integrated analysis of the mechanistic principles, formulation parameters, applications, and translational challenges of ultrasound-assisted nanoemulsification for food and nutraceutical applications. The review synthesizes findings on cavitation-driven droplet disruption, key operational parameters, and formulation factors governing nanoemulsion formation and performance. It also discusses applications in bioactive delivery, essential-oil-based preservation, and protein-based carrier systems. Key findings reveal that ultrasound can effectively produce sub-200 nm droplets through mechanical cavitation-driven disruption. However, excessive processing provides limited size reduction, whereas formulation composition determines emulsion stability and functionality. The review identifies that improved in vitro bioaccessibility does not constitute evidence of enhanced systemic bioavailability. Droplet size is a conditional rather than universal predictor of gastrointestinal delivery, and the interface paradox represents a fundamental design challenge that requires rational interfacial engineering. Persistent barriers to industrial translation include inconsistent parameter reporting, non-uniform cavitation fields during scale-up, and limited validation in complex food matrices. Future research priorities include standardized reporting of acoustic parameters, in vivo validation linking bioaccessibility with systemic bioavailability, pilot-scale studies, and interfacial engineering strategies to resolve the stability–digestibility trade-off.

Ultra-processed foods (UPFs) have become a growing part of everyday diets worldwide and have been linked to obesity, non-communicable diseases, and adverse mental health outcomes. Yet their role in deepening nutritional and health inequalities across socioeconomic groups and different stages of life is still not fully addressed in policy discussions. Drawing on recent population-based studies, longitudinal surveys, and mechanistic evidence, this perspective examines how UPF consumption intersects with food insecurity, psychosocial distress, and neurodevelopmental health from pregnancy through adulthood. Evidence from the United States shows that adults experiencing food insecurity obtain a larger share of their daily energy from UPFs. At the same time, surveys from low- and middle-income countries (LMICs) show that many infants and young children are already consuming sugar-sweetened beverages. Other observational studies have linked higher UPF intake with addictive-like eating behaviours and symptoms of depression, anxiety, and stress, although these studies cannot yet prove causality. In many LMICs, ongoing dietary transitions are also contributing to a rapid increase in overweight and obesity among socioeconomically disadvantaged groups, even while childhood stunting declines only slowly. Together, these findings suggest that UPF exposure is not only a dietary issue, but also a marker of wider social and nutritional vulnerability across the life-course. Breaking this cycle will require coordinated policy action, including stronger restrictions on unhealthy food marketing, front-of-package warning labels, better regulation of foods marketed to infants and young children, reforms to food-assistance programmes, and fiscal measures that make minimally processed foods more affordable and accessible.

Global policies on ultra-processed foods (UPF) have largely focused on four major approaches: taxes and other fiscal measures, restrictions on food marketing, front-of-pack warning labels, and product reformulation. While these strategies are important, they mainly address foods sold through commercial markets and overlook two powerful public-sector influences on what people eat: food assistance programs and nutrition policies during the first 1,000 days of life. These systems shape the diets of more than one billion people worldwide, yet they remain largely absent from current UPF policy discussions. This gap matters because those most affected by food environments often have the fewest choices. Infants, young children, and families relying on public food programs do not always determine what foods are available to them; instead, their diets are shaped by program design, procurement decisions, and broader policy priorities. If UPF policies continue to focus only on consumer choice within retail markets, they risk leaving behind populations who are most dependent on institutional food systems. A more complete approach requires expanding UPF governance beyond commercial food environments, including extending the protective principles of the WHO Code of Marketing of Breast-milk Substitutes to the broader complementary feeding period up to 36 months and developing age-specific UPF definitions and thresholds tailored to infants and young children. This perspective argues that a comprehensive, life-course approach to food-system regulation and the reduction of preventable nutrition-related inequalities requires the explicit integration of these overlooked yet critical domains into existing UPF policy frameworks.