The primary objective of this study is to evaluate plasma concentrations of Vitamin D (25-hydroxyvitamin D; 1,25-dihydroxyvitamin D) of different Vitamin D formulations in healthy volunteers at two concentrations. Pharmacokinetic parameters (Serum 25(OH)D and 1,25(OH)2D ng/ml) are compared with those of a regular Vitamin D formulation and a new (microencapsulated) LipoMicel Vitamin D formulation.

The secondary objective of this study is to evaluate safety blood parameters- The following blood parameters (serum levels) are checked: Alkaline Phosphatase, ALT, AST, Bilirubin, CRP, Creatinine, GGT. In addition, mineral levels-such as calcium, magnesium and phosphorus, potassium and sodium-are measured before and at the end of the study.

Study Design:

At least 40 healthy volunteers of both sexes in the age range 21-65 participate in a parallel, randomized blinded study conducted with different vitamin D3 products.

Each treatment is administered orally per day at a total dose of 1000 UI and 2500 IU vitamin d3 (cholecalciferol), together with breakfast, over a period of 30 days.

Participants are randomly divided into 4 groups (at least 10 per group):

The first group receives regular Vitamin D (1000IU), the second receives microencapsulated D3 (1000IU), the third group receives regular Vitamin D (2500IU), the fourth receives microencapsulated D3 (2500 IU).

Plasma concentrations (serum levels) of Vitamin D (25(OH)D and 1,25(OH)2D ng/ml are measured at baseline-before treatment start (day 0), during treatment (day 5, 10 and 15; one blood collection per day) and at end of treatment (day 30).

After the end of supplementation, blood vitamin D concentrations are checked again at day 45 and day 60.

The entire study session will span the course of 60 days. Participants are asked to attend 7 visits at LifeLabs to collect venous blood samples.

Each Vitamin D treatment is consumed with a glass of water along with breakfast for a period of 30 days.

Safety blood work is performed upon study enrolment, at the end of the Vitamin supplementation (day 30)- and at the end of the study (day 60) at Life Labs.

The following blood parameters are checked and must be within normal ranges to participate the study: Alkaline Phosphatase, ALT, AST, Bilirubin, CRP, Creatinine, GGT.

Mineral levels-such as calcium, magnesium and phosphorus-are measured before and at the end of the study (day 30).

All participants must understand written and spoken English and give written informed consent before any study specific procedure will be carried out.

All tested products are formulation manufactured by Factors Group.

Inclusion Criteria:

• age between 21 and 65 years; avoid consumption of any additional food supplements containing vitamin D; avoid use of tanning beds or other artificial UVB sources.

Participants must complete an online questionnaire on their medical history, weight, height, lifestyle (smoking, exercising etc.) and dietary habits relating to food rich in vitamin D, including other dietary supplementations.

Exclusion Criteria:

• use of vitamin D, calcium, magnesium, fish oil, or omega 3 fatty acids supplements; history of acute or chronic illness (such as gastrointestinal, liver and kidney disorders, osteoporosis …); pregnancy or lactation.