Effect of intermittent vitamin D3 on vascular function and symptoms in chronic fatigue syndrome--a randomised controlled trial.
Witham, M D, Adams, F, McSwiggan, S et al.·Nutrition, metabolism, and cardiovascular diseases : NMCD·2015
This study tested whether high-dose vitamin D supplements could improve blood vessel health and reduce fatigue in ME/CFS patients, since people with ME/CFS often have low vitamin D levels and poor blood vessel function. Fifty patients received either vitamin D3 (100,000 units every 2 months) or placebo for 6 months. The vitamin D supplements did increase vitamin D levels in the blood, but they did not improve blood vessel stiffness, blood pressure, cholesterol, or fatigue symptoms.