Pham H, Waterhouse M, Rahman S, et al. Vitamin D supplementation and cognition-Results from analyses of the D-Health trial. J Am Geriatr Soc. 2023 Jan 30. doi: 10.1111/jgs.18247. (Original study)

BACKGROUND: Observational studies have consistently found a link between low serum 25-hydroxyvitamin D concentration and higher risk of cognitive impairment. Results from randomized controlled trials have been mixed, and few have been conducted in the general population.

METHODS: We recruited 21,315 community-dwelling Australians aged between 60 and 84 years to participate in the D-Health Trial, a randomized, double-blind, placebo-controlled trial. The intervention was monthly oral doses of 60,000 international units of vitamin D or placebo for 5 years. We assessed cognitive function in a randomly sampled group of participants aged =70 years using the Telephone Interview for Cognitive Status (TICS) at 2 and 5 years after randomization. The primary outcome for this analysis was TICS score; the secondary outcome was the proportion of people who had cognitive impairment (defined as TICS score =25). We analyzed data using mixed models (linear and logistic).

RESULTS: We interviewed 3887 participants at year 2 and 3614 participants at year 5. The mean TICS score at these time points was 32.3 and 32.2, respectively. Vitamin D supplementation did not affect cognitive function as measured by TICS score (mean difference between vitamin D and placebo groups 0.04; 95% CI -0.14 to 0.23), or alter risk of cognitive impairment (odds ratio 1.00; 95% CI 0.75 to 1.33).

CONCLUSIONS: Monthly bolus doses of vitamin D supplementation neither enhanced nor hindered cognitive function among older adults. Population-wide vitamin D supplementation of older adults that are largely vitamin D replete is unlikely to substantially benefit cognition.

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Physician 5 / 7
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Comments from MORE raters

Nurse rater

This randomized blinded clinical trial with over 21,000 participants demonstrated that 60,000 units monthly of bolus doses of Vitamin D did not improve cognition (measured via telephone at yrs 2 and 5) among a subset of 4019 participants aged 60-84 yrs of age.

Physician rater

Vitamin D has no benefit to the brain.

Physician rater

Carefully conducted study of vitamin D supplementation in seniors with no effect on cognition.

Physician rater

It could be quibbled that the TICS is not the greatest measure of cognition, but other than that, this population-based study appears to confirm that Vit D supplementation is without benefit in those who are not Vit D deficient, at least in regard to cognition. Bad news for the supplement industry, but they are not usually constrained by evidence.

Physician rater

This is not a question that I had nor is it one that has ever been asked by one of my geriatric patients. I think the answer is fairly definitive and that might be worth sharing.

Physician rater

Vitamin D supplementation did not affect cognitive function as measured by TICS score.

Physician rater

Considering the degree to which Vitamin D continues to be "hyped," it is worth knowing that this intervention seems unlikely to be beneficial.
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