Vitamin D Supplementation Appears to Increase Plasma Aβ₄₀ in Vitamin D Insufficient Older Adults: A Pilot Randomized Controlled Trial

Low plasma amyloid-β (Aβ) is linked to Alzheimer's disease. Since vitamin D cleared brain Aβ in vitro, this 8-week trial examined whether vitamin D increased plasma Aβ₄₀. Vitamin D insufficient adults (6/18 M/F; 64.3 ± 10.9 y) were randomized to placebo or vitamin (50,000 IU/week) treatments. The vitamin group experienced greater plasma Aβ₄₀ change than controls, 14.9 ± 12.0 and 12.8 ± 12.8 pg/mL (p=0.045; effect size, 0.228). Change in Aβ₄₀ for older participants (≥60 y) was 18.3 ± 33.6 and 3.2 ± 44.5 pg/mL for vitamin (n=4) and placebo (n=4) groups (effect size, 0.295). Thus, vitamin D may increase plasma Aβ, particularly in older adults, suggesting decreased brain Aβ.