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.