Effects of Vitamin D Fortification on Vitamin D Metabolite Profiles and Status in Vitamin D Insufficient Individuals (VITD-2013)

Effects of Vitamin D Fortification on Vitamin D Metabolite Profiles and Status in Vitamin D Insufficient Individuals

A Double-Blind, Randomized, Control Study to Examine the Effects of Vitamin D Fortification on Vitamin D Metabolite Profiles and Status in Vitamin D Insufficient Individuals.

This is a cross-sectional study designed to compare plasma/serum and urine vitamin D metabolite profiles of vitamin D sufficient and insufficient individuals. There are two phases of this study. Phase 1 - Consented study participants will attend a screening visit and provide a fasting blood and urine sample. Those individuals who are vitamin D insufficient based on serum 25(OH)D concentrations will be invited to participate in Phase II Phase II - is a double-blind, randomized, control study designed to examine vitamin D status in vitamin D insufficient individuals consuming a water-soluble form of vitamin D3. Eligible participants will be asked to consume one of three beverages: i) rooibos iced-tea (control); ii) rooibos iced-tea fortified with 1000 IU of water-soluble vitamin D3; or iii) rooibos iced-tea fortified with 1000 IU of water-soluble vitamin D3 and 360 mg calcium at 240 mL of iced-tea consumed daily for 6 weeks. Participants will attend 6 weekly visits following baseline and provide a fasting blood sample for assessment of serum 25(OH)D concentrations. Objectives: 1) To investigate plasma/serum and urine vitamin D metabolite profiles in vitamin D sufficient and insufficient individuals; and 2) To determine the effects of vitamin D3 fortification on serum 25-dihydroxy-vitamin D [25(OH)D] concentrations, markers of vitamin D and calcium metabolism, and vitamin D metabolite profile in plasma/serum and urine of vitamin D insufficient individuals.

Health individuals from the general public will be recruited into this cross-sectional study designed to compare plasma/serum and urine vitamin D metabolite profiles of those identified as vitamin D sufficient and insufficient individuals. There are two objectives: Objective 1: To investigate plasma/serum and urine vitamin D metabolite profiles in vitamin D sufficient and insufficient individuals; N=20 and will consist of 10 individuals identified as vitamin D insufficient and 10 individuals identified as vitamin D deficient individuals. Objective 2: To determine the effects of vitamin D3 fortification on serum 25-dihydroxy-vitamin D [25(OH)D] concentrations, markers of vitamin D and calcium metabolism, and vitamin D metabolite profile in plasma/serum and urine of vitamin D insufficient individuals. N=45. To achieve the objectives, the study will be conducted in two phases: Phase 1 - Healthy males or females, ≥19 and ≤50 years of age, will be recruited from the general public. Consented study participants will provide a fasting blood and urine sample for the purpose of determination of vitamin D status (insufficient vs. deficient) based on serum 25(OH)D concentrations. Forty-five (45) individuals identified as vitamin D insufficient (having a serum 25(OH)D concentration ≥30 and ≤75 nmol/L) will proceed to phase II. A N=20 (10 vitamin D insufficient and 10 vitamin D deficient) will also be identified to satisfy objective 1. Phase II - is a double-blind, randomized, control study designed to examine vitamin D status in vitamin D insufficient individuals consuming a water-soluble form of vitamin D3. Eligible participants will randomized to consume one of three beverages: i) rooibos iced-tea (control); ii) rooibos iced-tea fortified with 1000 IU of water-soluble vitamin D3; or iii) rooibos iced-tea fortified with 1000 IU of water-soluble vitamin D3 and 360 mg calcium at 240 mL of iced-tea consumed daily for 6 weeks. Both researchers and participants will be blinded to the beverage group assigned to each participant. Participants will then attend 6 weekly visits following the baseline visit to provide fasting blood samples for assessment of serum 25(OH)D concentrations. Analysis of intact-PTH, alkaline-phosphatase, calcium, phosphorus, CRP, TAP and vitamin D metabolite profile and a urine sample will also be obtained for assessment of N-telopeptide and vitamin D metabolite profile will also occur at Baseline and Week 6. Fasting blood samples collected at week 3 will be used for additional assessment of serum alkaline phosphatase, calcium and phosphorus. A 3-day Food Record will be provided at week 3. Vitamin D insufficient participants will be stratified according to their serum 25(OH)D concentrations (≥30 and ≤50, or >50 and ≤75 nmol/L) after screening and prior to the beverage study to ensure that a range of lower and higher serum 25(OH)D concentrations are represented in each beverage group.

Participants will be instructed to consume 240 mL of iced-tea daily for 6 weeks. The iced-tea beverages do not contain added sugar or artificial sweeteners. Beverages will be prepared fresh weekly and picked up by participants during their weekly study visits.

Participants will be instructed to consume 240 mL of iced-tea fortified with 1000 IU water-soluable vitamin D3 daily for 6 weeks. The iced-tea beverages do not contain added sugar or artificial sweeteners. Beverages will be prepared fresh weekly and picked up by participants during their weekly study visits.

Participants will be instructed to consume 240 mL of Rooibos iced-tea fortified with 1000 IU of water-soluable vitamin D3 and 360 mg of calcium daily for 6 weeks. The iced-tea beverages do not contain added sugar or artificial sweeteners. Beverages will be prepared fresh weekly and picked up by participants during their weekly study visits.

Participants will consume 240 mL of Rooibos iced-tea daily for 6 weeks. The iced-tea beverage will not contain any added sugar or artificial sweeteners. Beverages will be prepared fresh weekly and picked up by participants during their weekly study visits.

Participants will consume 240 mL of Rooibos iced-tea fortified with 1000 IU of water soluable Vitamin D3 daily for 6 weeks. The iced-tea beverage will not contain any added sugar or artificial sweeteners. Beverages will be prepared fresh weekly and picked up by participants during their weekly study visits.

Participants will consume 240 mL of Rooibos iced-tea fortified with 1000 IU of water soluable Vitamin D3 and 360 mg of Calicum daily for 6 weeks. The iced-tea beverage will not contain any added sugar or artificial sweeteners. Beverages will be prepared fresh weekly and picked up by participants during their weekly study visits.

Plasma/Serum and Urine Vitamin D Metabolite Profiles of Vitamin D Sufficient and Insufficient Individuals

To investigate plasma/serum and urine vitamin D metabolite profiles in vitamin D sufficient and insufficient individuals.

To determine the effects of 6 weeks of vitamin D3 fortification on serum 25-dihydroxy-vitamin D [25(OH)D] concentrations of vitamin D insufficient individuals.

The Effects of Vitamin D3 Fortification on markers of vitamin D of vitamin D insufficient individuals

To determine the effects of 6 weeks of vitamin D3 fortification on markers of vitamin D in plasma/serum and urine of vitamin D insufficient individuals.

To determine the effects of 6 weeks of vitamin D3 fortification on calcium metabolism in plasma/serum and urine of vitamin D insufficient individuals.

The Effects of Vitamin D3 Fortification on Vitamin D Metabolite Profile of Vitamin D Insufficient Individuals.

Determine the effects of vitamin D3 fortification on the vitamin D metabolite profile in plasma/serum and urine of vitamin D insufficient individuals.

Inclusion Criteria: A. Inclusion Criteria for Objective 1 (Part One): Adult volunteers, male or female, between 19 and 50 years of age; Body mass index (BMI) ≥20 and ≤30 kg/m2 (normal to overweight); Must be on a stable regime for the past three months, if taking vitamin and mineral/dietary/herbal supplements; and Willing to provide informed consent. B. Inclusion Criteria for Objective 2 (Part Two): Adult volunteers, male or female, between 19 and 50 years of age; Body mass index (BMI) ≥20 and ≤30 kg/m2 (normal to overweight); Must be on a stable regime for the past three months, if taking vitamin and mineral/dietary/herbal supplements; Vitamin D insufficient (serum 25(OH)D concentrations ≥30 and ≤75 nmol/L); Willing to comply with protocol requirements; and Willing to provide informed consent. Exclusion Criteria: Take a vitamin D or calcium supplement within the last three months before the start date of the study, or during the study; History of vitamin D deficiency (serum 25(OH)D concentration <30 nmol/L); History of hypocalcaemia; Presence of a clinically diagnosed disease affecting the circulatory, respiratory, immune, skeletal, urinary, muscular, endocrine, digestive, nervous or reproductive system that requires medical treatment; Taking any medication (with the exception of birth control); Daily consumption of more than three servings of dairy products; Undergone significant sun exposure one month before start date of the study; Use or have used a tanning booth one month before start date of the study, or during the study; Plan to travel to a sunny climate during the study; Currently smoking or have smoked within the last six months before start date of the study, or during the study; Have allergies to tea products; Pregnant or lactating; and Consume excessive alcohol (>10 drinks/week for women, >15 drinks/week for men).

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