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

Low plasma amyloid-beta (A beta) is linked to Alzheimer's disease. Since vitamin D cleared brain A beta in vitro, this 8-week trial examined whether vitamin D increased plasma A beta(40). 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 A beta(40) change than controls, + 14.9 +/- 12.0 and + 12.8 +/- 12.8 pg/mL (p = 0.045; effect size, 0.228). Change in A beta(40) 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 A beta, particularly in older adults, suggesting decreased brain A beta.