Virtual Nature, Metaverse, and NAD⁺: A Narrative Review for Health Planning and Healthy Ageing.

Background and Aims: Digital experiences-including virtual reality (VR), the metaverse, and exergaming-shape stress, mental health, and physical activity. While nature-related and urban digital experiences influence health behaviors through different pathways, their impact on nicotinamide adenine dinucleotide (NAD⁺), a key mediator of cellular ageing, remains unclear. This review aims to synthesize evidence and construct a conceptual framework linking these domains. Methods: We conducted a scoping narrative review synthesizing systematic reviews, meta-analyses, randomized trials, and observational studies. Approximately 50 key publications were identified through database searches and purposively selected to represent major evidence domains and mechanisms linking VR, stress, physical activity, and NAD⁺ metabolism. Results: VR nature and digital nature reduce stress, anxiety, and physiological stress markers such as cortisol. In contrast, metaverse environments may enhance positive affect and social connectedness but are also associated with sedentary behavior and potential social fatigue. Immersive VR exercise (exergaming) generates moderate-to-vigorous physical activity comparable to traditional exercise and may enhance NAD⁺ metabolism via NAMPT activation. However, no human study has yet simultaneously assessed VR interventions and blood NAD⁺ levels. Conclusion: We propose a conceptual model linking digital experiences to NAD⁺ metabolism via stress, physical activity, and sleep. This framework highlights a key scientific gap and provides a foundation for future research and health planning.