The Effect of Vitamin D Sublingual Spray on Vitamin D3 Levels in the Blood Compared to Other Forms of Vitamin D3

This randomized comparative study was performed in Liepaja, Latvia, on 99 outpatients, with vitamin D levels below 30 ng/ml. Participants were randomized into three groups to receive vitamin D3 supplementation in three different forms - sublingual spray, oral oil droplets, and capsules. Before intervention blood samples were taken to determine vitamin D3 level, creatinine, and GFR, each participant received vitamin D3 4000 IU daily for 30 days. After that blood test was performed again, to measure changes in vitamin D3 levels in the blood. Participants answered the questionnaire to collect information about things that might affect vitamin D3 levels, such as dietary habits, physical activities, usage of sunscreen, compliance, etc.