Table 4.

Information on the interventions and variables analyzed.

References	Supplementation time	Rating for the 25OHD level at the start of the intervention	Administration route/vit D dose	Cognitive domains analyzed
Pettersen (2017)	18 weeks	Insufficient	Oral 1 tablet 400 IU/d 4 pcs 1,000 IU/d	Processing speed; Executive function; Verbal learning/memory.
Jorde et al. (2019)	4 months	Deficient	Oral 20,000 IU/s	Short-term verbal and visual memory; Attention.
Dean et al. (2011)	6 weeks	Adequate	Oral 5,000 IU/d	Executive function.
Rossom et al. (2012)	84 months	Deficient/Insufficient	Oral 400 IU/d	General cognitive function; Attention and working memory; Verbal memory.
Schietzel et al. (2019)	24 months	Deficient	Oral 2,000 IU/d 800 IU/d	Global Cognition; Executive functions; Learning/memory.
Zajac et al. (2020)	6 months	Adequate	Oral (pill or diet) 600 IU/d	Processing speed; Reaction/attention time; verbal and spatial working memory; Overall memory quality.
Beauchet et al. (2019)	3 months	Deficient	Oral Fortified yogurt with 200 IU/2x d	Attention; Processing speed; verbal memory; Attention; Executive function.
Castle et al. (2020)	12 months	Insufficient	Oral 600 IU/d 2,000 IU/d 4,000 IU/d	Executive functioning; Learning/memory; Attention; General cognitive ability.
Owusu et al. (2019)	36 months	Insufficient	Oral 2,400 IU/d 3,600 IU/d 4,800 IU/d	General cognitive function.

IU/d, International Unit per day; IU/s, International Unit per week; Vit D, Vitamin D.