Is vitamin D effective to treat fatigue in healthy persons with low vitamin D levels?

A single large dose—100,000 units—of vitamin D increased vitamin D blood levels but did not affect fatigue to a clinically greater extent than placebo. (LOE = 1b)

Nowak A, Boesch L, Andres E, et al. Effect of vitamin D3 on self-perceived fatigue. A double-blind randomized placebo-controlled trial. Medicine 2016;95(52):e5353.  [PMID:28033244]

Randomized controlled trial (double-blinded)

Foundation

Concealed

Outpatient (any)

These investigators enrolled 120 patients (53% women, average age 29 years) with fatigue and a vitamin D deficiency. They excluded patients with known mental disorders, but did not specifically screen for anxiety or depression. The patients were at the low end of scores signifying fatigue: an average 24.9 and 23.3 of a possible 50 points in the treated and placebo groups, respectively (scores < 22 are considered normal). The investigators randomized patients, using concealed allocation, to receive a single dose of placebo or 100,000 units vitamin D (cholecalciferol). One month later the scores decreased (improved) an average 3.3 points in the treated group as compared with a 0.8-point average improvement in the placebo group. The difference in improvement, 2.5 points, is not clinically important—the minimum clinically important difference on the scoring system is 4 points.