This vitamin has been shown to improve cognitive function in Alzheimer’s patients.

This study investigated the effect of a 12-month vitamin D supplementation on cognitive function and amyloid beta (Aβ)-related biomarkers in patients with Alzheimer's disease (Jia J, et.al., 2019).

The research was randomized, double-blind, and placebo controlled. 210 patients were divided into either a treatment group which took 800 IU of vitamin D per day for 12 months or a placebo group.

Tests of cognitive performance and Aβ-related biomarkers were measured at the start of the study and at 6 months and 12 months.

The results showed that the patients who took vitamin D had a significant improvement in amyloid beta related biomarkers and tests related to cognitive function compared to the control group.

The treatment group also had a significant increase in IQ.

Reference

Jingya Jia, Jing Hu, Xiaoxu Huo, Rujuan Miao, Yanping Zhang, Fei Ma, Effects of vitamin D supplementation on cognitive function and blood Aβ-related biomarkers in older adults with Alzheimer's disease: a randomised, double-blind, placebo-controlled trial, J Neurol Neurosurg Psychiatry. 2019 Dec;90(12):1347-1352.

Vitamin D3