Effect of Vitamin D Oral Supplements on 25 OH Vitamin D Levels

• Cmax of 25 OH vitamin D [ Time Frame: 140 days ] [ Designated as safety issue: No ]
  Cmax of total 25 OH vitamin D over the treatment period of 140 days
• Tmax of 25 OH vitamin D level [ Time Frame: 140 days ] [ Designated as safety issue: No ]
  Tmax of total 25 OH vitamin D over the treatment period of 140 days
• area under the curve of vitamin D level [ Time Frame: 140 days ] [ Designated as safety issue: No ]
  area under the curve of total vitamin D level over 140 days
• incidence of hypercalcemia [ Time Frame: 140 days ] [ Designated as safety issue: Yes ]
• incidence of hypercalciuria [ Time Frame: 140 days ] [ Designated as safety issue: Yes ]

Vitamin D deficiency is common world wide. 25 OH vitamin D level is the best indicator of vitamin D status. Vitamin D supplements are available as vitamin D2 or D3, in small daily or large weekly/monthly doses. Controversy continues on the relative potency of vitamin D2 compared to D3 and of daily compared to weekly or monthly doses, in increasing/maintaining total 25 OH vitamin D level.

The investigators plan to conduct a controlled trial to compare the effect of various vitamin D supplements on 25 OH vitamin D levels in healthy adults with starting 25 OH vitamin D level between 20 to 50 nmol/L.

• Drug: ergocalciferol 2000 IU orally, daily
  ergocalciferol 2000 IU orally, daily
  Other Name: ergocalciferol
• Drug: ergocalciferol 25000 IU oraly every 2 weeks
  ergocalciferol 25000 IU oraly every 2 weeks
  Other Name: ergocalciferol
• Drug: ergocalciferol 50000 IU orally every 4 weeks
  ergocalciferol 50000 IU orally every 4 weeks
  Other Name: ergocalciferol
• Drug: ergocal1000 IU & cholecal 1000 IU orally daily
  ergocalciferol 1000 IU and cholecalciferol 1000 IU orally every day
  Other Name: ergocalciferol and cholecalciferol
• Drug: cholecalciferol 2000 IU orally daily
  cholecalciferol 2000 IU orally everyday
  Other Name: cholecalciferol
• Drug: Cholecalciferol 25000 IU orally every 2 weeks
  Cholecalciferol 25000 IU orally every 2 weeks
  Other Name: Cholecalciferol
• Drug: Cholecalciferol 50000 orally every 4 weeks
  Cholecalciferol 50000 orally every 4 weeks
  Other Name: Cholecalciferol
• Drug: placebo orally everyday
  placebo orally everyday
  Other Name: placebo

• Active Comparator: D2 2000 IU daily
  Intervention: Drug: ergocalciferol 2000 IU orally, daily
• Active Comparator: D3 2000 IU daily
  Intervention: Drug: cholecalciferol 2000 IU orally daily
• Active Comparator: D2 1000 IU + D3 1000 IU daily
  Intervention: Drug: ergocal1000 IU & cholecal 1000 IU orally daily
• Active Comparator: D2 25000 IU Q2wk
  Intervention: Drug: ergocalciferol 25000 IU oraly every 2 weeks
• Active Comparator: D3 25000 IU Q2wk
  Intervention: Drug: Cholecalciferol 25000 IU orally every 2 weeks
• Active Comparator: D2 50000 IU Q4wk
  Intervention: Drug: ergocalciferol 50000 IU orally every 4 weeks
• Active Comparator: D3 50000 IU Q4wk
  Intervention: Drug: Cholecalciferol 50000 orally every 4 weeks
• Placebo Comparator: placebo daily
  Intervention: Drug: placebo orally everyday

Inclusion Criteria:

• Healthy adults living in Riyadh area who consume no more than one serving of milk/day, do not take vitamin supplement, habitually have less than 10 hr of sun exposure per week, don't suffer from granulomatous conditions, liver disease, or kidney disease, and don't take anticonvulsants, barbiturates, or steroids.
• 25 OH vitamin D level between 20 to 50 nmol/L.