Vitamin D supplementation has no effect on cognitive performance after four months in mid-aged and older subjects

Abstract

BackgroundLow serum 25-hydroxyvitamin D (25(OH)D) levels are associated with impaired cognitive function, but the effect of vitamin D supplementation on cognitive function is uncertain. Methods422 subjects were included in a randomized controlled trial with vitamin D (cholecalciferol) 100,000 IU given as a bolus dose followed by 20,000 IU per week versus placebo for four months. Cognitive function was evaluated with verbal recall test, coding test and tapping test. Results374 subjects (mean age 52 years, 198 males) had complete cognitive tests both at baseline and at end of study. Mean baseline serum 25(OH)D level was 34 nmol/L. At baseline there were no significant associations between serum 25(OH)D and the three separate cognitive tests. At the end of the study mean serum 25(OH)D levels were 89 nmol/L and 31 nmol/L in the vitamin D and placebo groups, respectively. At the end of the study, there were no statistically significant differences between the two groups regarding change in the cognitive test scores. Nor did sub-group analyses based on gender, age, baseline serum 25(OH)D and cognitive test scores reveal significant differences between the two groups at the end of the study. ConclusionsVitamin D supplementation did not improve cognitive function during a four months intervention in mid-aged and older subjects. Trial registrationClinicalTrials.govNCT02750293