Table 1. Inclusion and exclusion criteria according to the PICOS criteria¹.

PICOS component	Inclusion criteria	Exclusion criteria
Participants
	Samples including adults aged ≥ 50 yrs. Community-dwelling adults	Studies exclusively targeting age groups < 50 yrs. Institutionalized adults (e.g., living in a care facility) Studies focusing on patient collectives or clinical research participants
Intervention/Context
	Studies researching older adults’ acceptance of general nutrition and/or fitness apps compared to younger adults	Studies with a focus on disease management or treatment apps were excluded (e.g., nutrition app for managing diabetes) .
Outcomes
	Any dimension(s) of nutrition and/or fitness app acceptance defined by the studies’ authors (e.g., frequency of usage, perceived usefulness) Age effects, i.e., age-group-specific differences in nutrition and/or app acceptance	Studies focusing on general health apps without presenting specific results for either nutrition or/and fitness apps Studies not reporting any age effects (or the lack thereof), i.e., age-group-specific results regarding nutrition and/or fitness app acceptance
Study design
	Original articles Qualitative studies Quantitative studies Mixed methods studies	Intervention studies, feasibility studies (e.g., evaluating the effectiveness of nutrition and/or fitness apps) Non-original articles (e.g., conference abstracts, book chapters) Literature reviews Grey literature

Note.

¹PICOS = Population, Intervention/ Context, Outcomes, and Study Type; yrs. = years