Vitamin D plays a very important role in the human body as it contributes to the maintenance of normal bones and normal function of the immune system. Numerous reports showed high prevalence of low vitamin D intake and vitamin D deficiency in Europe – particularly during the winter season, indicating the importance of vitamin D supplementation. There is some confusion regarding the dosages, as different associations recommend different amounts of daily intake of vitamin D. Question about appropriate dosing and formulation of vitamin D supplementation therefore arises. To get a more accurate answer to that question, Valens initiated a study about treating suboptimal vitamin D status that was conducted in Slovenia.

Our goal was to prove efficiency of treating suboptimal vitamin D status with 25 µg (1000 IU) of vitamin D3 per day using different vitamin D3 (cholecalciferol) formulations, which are most commonly used in supplements. Two Valens products were used in the trial: Valens D 1000 oral spray (water-based) and Valens D-Natural (oil-based).

The clinical study lasted from January to March. The study was conducted on 105 humans with suboptimal vitamin D status (12-20 µg/L). 21% of initial 235 human subjects had severe vitamin D deficiency (<12 µg/L).

Results of the study

1. Both tested Valens Vitamin D formulations are efficient in improving suboptimal vitamin D status. 99 (94 %) participants finished the trial successfully. Daily supplementation of 1000 IU vitamin D during winter resulted in considerable increase in average serum vitamin D levels (for 13 mg/L) in both treatment groups using Valens vitamin D oral sprays. Average serum vitamin D levels were also considerably higher compared to the control group. On the other hand, control serum vitamin D level in the control group was further lowered from January to March.

2. Inhabitants of Continental Europe don’t get enough vitamin D in the wintertime due to inadequate exposure to sunlight. The study confirmed high prevalence of vitamin D deficiency in the winter season. 66 % of the subjects had suboptimal serum vitamin D levels ( 20 µg/L), while 21 % had serum vitamin D levels even below 12 µg/L. Those weren’t able to participate in a study.

3. Most participants required higher dosages for reaching optimal vitamin D status. The study indicates that the dosage of 1000 IU daily might not be sufficient for maintaining optimal vitamin D status during winter. After 2 months of supplementation, serum vitamin D levels were still below 30 mcg/L in 77% of the subjects, indicating they would either need higher doses of vitamin D or should start with supplementation earlier.