D-Light Intervention

Sponsor

University of Ulster (Other)

Overall Status

Completed

CT.gov ID

NCT02495584

Collaborator

Dairy Council for Northern Ireland (Other), Agri-food & Biosciences Institute (Other), Center for Nutrition and Health, RIVM (The Netherlands) (Other)

Enrollment

Location

Arms

Duration (Months)

Patients Per Site Per Month

Study Details

Study Description

Brief Summary

Vitamin D insufficiency has become a global concern, with low vitamin D status associated with bone disorders, cardiovascular disease and certain cancers. The United Kingdom (UK) and Ireland are at particular risk of vitamin D deficiency owing to the northerly latitude, increased use of sunscreen, decreased sun exposure and a high level of cloud cover. A recent survey in the UK showed that more than 50% of UK adults have insufficient vitamin D status, with lower levels noted in the winter months. Variations in vitamin D status have been known to vary between summer and winter, owing to our northern latitude (52-55°N) the Ultraviolet (UV)-B intensity in Northern Ireland is inadequate to promote the dermal synthesis of vitamin D during the winter months, causing us to rely on dietary sources. The aim of this intervention is to investigate the main effects of vitamin D3-fortified milk and supplemental vitamin D3 on vitamin D status and functional health outcomes during the winter, and how this intervention will affect subsequent dermal synthesis of vitamin D from UV exposure. Participants will be recruited from the local community. Blood samples will be collected from each participant at two timepoints (September/October and March/April). Pre- and post-intervention blood pressure, grip strength, height, weight, waist and hip circumferences will be measured, in addition participants will undergo a dual energy x-ray absorptiometry (DXA) scan to assess body composition and bone mineral density. Information on general health, lifestyle, physical activity, dietary intake and typical behaviours in the sun will be collected. Following the dietary intervention, a subset of participants will be invited to participate in a follow-up study, examining UV exposure during the summer months, when they will wear a personal wrist dosimeter for 1 month, complete a sun dairy and provide 2 additional blood samples.

Condition or Disease	Intervention/Treatment	Phase
25-hydroxyvitamin D Concentration (Vitamin D Status)	Dietary Supplement: Fortified milk (10µg vitamin D3) Dietary Supplement: Unfortified milk (placebo) Dietary Supplement: 10µg vitamin D3 supplement Dietary Supplement: Placebo supplement	N/A

Study Design

Study Type:

Interventional

Actual Enrollment :

52 participants

Allocation:

Randomized

Intervention Model:

Factorial Assignment

Masking:

Double (Participant, Investigator)

Primary Purpose:

Prevention

Official Title:

D-Light Intervention: A Randomised Controlled Human Intervention Study to Assess the Impact of Vitamin D From Milk and Supplements on Functional Health Outcomes and Future Vitamin D Synthesis From UV Exposure

Study Start Date :

Sep 1, 2014

Actual Primary Completion Date :

Oct 1, 2015

Actual Study Completion Date :

Oct 1, 2015

Arms and Interventions

Arm	Intervention/Treatment
Experimental: Treatment 1 500ml fortified milk (10µg vitamin D3) +1 supplement capsule (10µg vitamin D3) daily for 24 weeks	Dietary Supplement: Fortified milk (10µg vitamin D3) Dietary Supplement: 10µg vitamin D3 supplement
Experimental: Treatment 2 500ml fortified milk (10µg vitamin D3) +1 supplement capsule (placebo) daily for 24 weeks	Dietary Supplement: Fortified milk (10µg vitamin D3) Dietary Supplement: Placebo supplement
Experimental: Treatment 3 500ml unfortified milk (placebo) +1 supplement capsule (10µg vitamin D3) daily for 24 weeks	Dietary Supplement: Unfortified milk (placebo) Dietary Supplement: 10µg vitamin D3 supplement
Placebo Comparator: Treatment 4 500ml unfortified milk (placebo) +1 supplement capsule (placebo) daily for 24 weeks	Dietary Supplement: Unfortified milk (placebo) Dietary Supplement: Placebo supplement

Outcome Measures

Primary Outcome Measures

Change in vitamin D status (25-hydroxyvitamin D serum concentration) [Baseline + post-intervention (24weeks)]
Blood analysis

Secondary Outcome Measures

Change in body composition [Baseline + post-intervention (24weeks)]
Assessed by dual energy X-ray absorptiometry (DXA)
Change in muscle strength [Baseline + post-intervention (24weeks)]
Assessed by grip strength
Change in inflammation status [Baseline + post-intervention (24weeks)]
Blood analysis
Change in lipid profile [Baseline + post-intervention (24weeks)]
Blood analysis
Change in glucose levels [Baseline + post-intervention (24weeks)]
Blood analysis
Change in insulin concentrations [Baseline + post-intervention (24weeks)]
Blood analysis

Other Outcome Measures

UV exposure (follow-up) [8 weeks post-intervention (32-40 weeks)]
Assessed by UV wrist monitors

Eligibility Criteria

Criteria

Ages Eligible for Study:

20 Years to 40 Years

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

Yes

Inclusion Criteria:

20-40 years old
Apparently healthy
Living on the island of Ireland

Exclusion Criteria:

Below 20 years and aged 40 years or above
Not living on the island of Ireland
Pregnant or lactating women and those planning to become pregnant
Individuals who have been taking a vitamin D or calcium containing supplement in the previous three months
Those with food intolerances or allergies that would affect their ability to consume study milk
Individuals following a diet which excludes milk (e.g. vegans)
Those with a diagnosed chronic medical condition or on prescribed medication known to effect vitamin D metabolism
Those who are planning a sun holiday during the winter months (Oct-Mar)
Adults with learning, or any other difficulties that would prevent them from completing the study protocol