Table 1.

Studies on vitamin K concentration and cognitive performances.

References	Participants	Design	Vitamin K determination	Cognitive evaluation	Main results	Strenghts	Limitations
Sato et al. (61)	100 demented women (mean age 81), 100 cognitively normal female controls (mean age 81)	Cross Sectional	Standardized HPLCa procedures	MMSEb	Patients with severe dementia found to have a lower Vitamin K serum concentration	Reliable methodology for serum levels of vitamin K	No follow-up, relatively small sample size
Presse et al. (62)	31 ADc patients and 31 healthy controls (mean age 78)	Cross Sectional	Vitamin K intake measured using 3- or 4-days diet records	MMSEb	9 patients with ADc found to have a lower intake of vitamin K	Accuracy of food records ensured with a dietitian and the help of caregivers	Dietary intake data of limited value for assessing vitamin K status, small sample size, potential over selection of patients
Presse et al. (63)	320 elderly (mean age 76) from Québec Longitudinal NuAge Study	Cross Sectional	Standardized HPLCa procedures	MMMSEd, 6 tests covering 4 cognitive domains	Positive association between higher vitamin K intake and verbal episodic memory	Comprehensive cognitive battery assessing 4 cognitive domains, large sample size, reliable methodology for serum levels of vitamin K	No follow-up, potential confounders (such as ApoE genotype) potential over selection of patients
Van der Heuvel et al. (60)	599 participants (mean age 60) from the Longitudinal Aging Study Amsterdam	Prospective (follow up: 6 years)	dp-ucMGPe	Alphabet coding task, Auditory verbal learning test, Raven's colored progressive matrices	No association found between dp-ucMPGe and cognitive functions	Inclusion of a range of cognitive tests sensitive to aging measured over 6 years follow-up	Indirect measure of vitamin K status (dp-ucMGPe), only a single measurement of Vitamin K status was available
Chouet et al. (64)	192 patients (mean age 83) recruited from the Cognition and LIPophilic vitamins study	Cross Sectional	FFQf	MMSEb, FBRSg	Positive association between vitamin K intake and MMSEb and FBRSg scores	Assessment of the dietary vitamin K intake over 12 months, assessment of both cognitive and behavioral outcomes	FFQg validated on Canadian population (tends to overestimate intakes), poor estimation of Vitamin K intake in patients with cognitive disorders
Soutif-Veillon et al. (65)	160 patients (mean age 82) recruited from the Cognition and LIPophilic vitamins study	Cross Sectional	FFQf	MAC-Qh	Positive association between vitamin K intake and memory complaint questionnaire score	Assessment of the dietary phylloquinone intake over 12 months	Use of MAC-Qh tool may have overestimated the prevalence of subjective memory complaint, poor estimation of vitamin K dietary intake in patients with cognitive disorders
Kiely et al. (66)	156 elderly (mean age 78) from ELDERMET cohort	Cross Sectional	FFQf and HPLCa	MMSEb	Serum and dietary phylloquinone were significant and independent predictors of good cognitive function	Simultaneous measurement of both dietary and serum phylloquinone	Self-selected, motivated cohort, with potentially better diet, education, and lifestyle than general population

^aHigh Performance Liquid Cromatography.

^bMini-Mental State Examination.

^cAlzheimer's Disease.

^dModified Mini-Mental State Examination.

^eDesphospho-uncarboxylated matrix Gla protein.

^fFood Frequency Questionnaire.

^gFrontotemporal Behavioral Rating Scale.

^hMemory Complaint Questionnaire.