Challenges in Achieving Adequate Vitamin D Status in the Adult Population - Part 1 (VITAD/1)

Seasonal variations in vitamin D status will be determined on a cohort of Slovenian adults using longitudinal study design, and association between vitamin D status and different Caucasian phototypes, skin colour and melanin index investigated .

Study Overview

• Status: Completed
• Conditions: Vitamin D Serum Levels

• Study Type: Observational
• Enrollment (Actual): 338

Contacts and Locations

Study Locations

• Slovenia
  • Ljubljana, Slovenia, 1000
    • Nutrition Institute, Ljubljana

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

• Sampling Method: Probability Sample

Study Population

General Slovenian adult population, men and women, skin phototypes I-IV.

Description

Inclusion Criteria:

• Signed Informed consent form (ICF),
• Caucasian race
• Age between 18 and 65 years at the time of the signature of Informed consent form (ICF),
• Willingness to avoid a consumption of any food supplements containing Vitamin D during the study, except the ones prescribed by the study researchers, and to avoid use of solarium or other artificial UVB sources
• Willingness to follow all study procedures

Exclusion Criteria:

• Pregnancy or breastfeeding,
• Known or suspected allergy to any ingredient of the tested products in Part 2,
• Pronounced avoidance of sunshine (eg reporting of allergy to the sun)
• Use of food supplements containing Vitamin D or fish oil or omega 3 fatty acids in last three months prior to inclusion,
• Special dietary habits used by a small part of the population (veganism, low-carb hihg-fat diet, caloric restriction diet, note: vegetarians are not excluded)
• Diets prescribed by the medical profession
• Disorders of the kidneys, thyroid, digestive tract, osteoporosis and other bone diseases, skin diseases
• Other diseases and conditions that affect the absorption and synthesis of vitamin D
• Exposure to stronger sunlight in the last three months prior to engaging in a survey (travel to countries with stronger sunshine, use of solarium),
• The consumption of margarine or plant substitutes for milk / milk products several times a day, as these foods are most often enriched with vitamin D,
• Visiting the solarium in the last three months before joining the survey,
• Mental incapacity that precludes adequate understanding or cooperation.

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Difference between vitamin D serum levels in winter and in summer season will be determined	Vitamin D serum level will be measured once in winter (December - January) and once in summer season (August-September) for each individual. The study will be performed over two consecutive years.	2 years

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Correlation of vitamin D serum levels with Fitzpatrick skin phototype	Fitzpatrick skin phototype will be determined using Fitzpatrick self-evaluation questionnaire in combination with expert assessment in August-September.	2 years
Correlation of vitamin D serum levels with skin colour measured in CIE Lab colour space	Skin colour will be measured in CIE Lab colour space on inner and outer side of the upper arm. The measurement will be performed in August-September.	2 years
Correlation of vitamin D serum levels with melanin index	Melanin index will be measured on inner and outer side of the upper arm. The measurement will be performed in August-September.	2 years

Collaborators and Investigators

• Sponsor: Nutrition Institute, Slovenia
• Collaborators: Slovenian Research Agency; Valens Int. d.o.o., Slovenija; VIST - Faculty of Applied Sciences
• Investigators: Principal Investigator: Katja Žmitek, PhD, Researcher

Study record dates

Study Major Dates

• Study Start (Actual): January 8, 2019
• Primary Completion (Actual): September 28, 2020
• Study Completion (Actual): September 28, 2020

Study Registration Dates

• First Submitted: January 17, 2019
• First Submitted That Met QC Criteria: January 25, 2019
• First Posted (Actual): January 28, 2019

Study Record Updates

• Last Update Posted (Actual): June 18, 2021
• Last Update Submitted That Met QC Criteria: June 16, 2021
• Last Verified: June 1, 2021

More Information

Terms related to this study

• Other Study ID Numbers: VITAD-01-2018 Part 1

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No