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Information on the latest vitamin D news and research.

Find out more information on deficiency, supplementation, sun exposure, and how vitamin D relates to your health.

New RCT determines dose-response to vitamin D in obese individuals

A randomized controlled trial looked at the dose-response relationship of vitamin D supplementation in obese participants after two months and found that it was significantly lower than healthy participants. In other words, obese participants required more vitamin D to reach similar levels as healthy participants.

The dose-response relationship describes the change in effect in an organism caused by differing levels of doses of substances after a certain amount of time. In this study, the researchers were looking at how a certain dose of supplemental vitamin D affected the serum vitamin D levels in obese individuals after two months.

Obesity is considered a risk factor for vitamin D deficiency. Obese individuals have consistently been found to have lower vitamin D levels and a greater likelihood of deficiency than non-obese individuals.

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  About: Will Hunter

Will is the Program Associate of the Vitamin D council and works on website administration, content production and editing, and fundraising. He is passionate about nutrition, exercise, and technology and how they relate to health and longevity.

One Response to New RCT determines dose-response to vitamin D in obese individuals

  1. Ted says:

    Or you could look at a longer trial with a larger number of participants taking higher doses of Vitamin D.

    J Clin Endocrinol Metab. 2013 Dec;98(12):4845-51. doi: 10.1210/jc.2012-4103. Epub 2013 Sep 13.
    25-Hydroxyvitamin D response to graded vitamin D₃ supplementation among obese adults.
    Drincic A1, Fuller E, Heaney RP, Armas LA.
    Author information

    Guidelines have suggested that obese adults need 2 to 3 times more vitamin D than lean adults to treat vitamin D deficiency, but few studies have evaluated the vitamin D dose response in obese subjects.

    The purpose of this study was to characterize the pharmacokinetics of 25-hydroxyvitamin D [25(OH)D] response to 3 different doses of vitamin D₃ (cholecalciferol) in a group of obese subjects and to quantify the 25(OH)D dose-response relationship. DESIGN, SETTING, INTERVENTION, PATIENTS: This was a randomized, single-blind study of 3 doses of oral vitamin D₃ (1000, 5000, or 10,000 IU) given daily to 67 obese subjects for 21 weeks during the winter months.

    Serum 25(OH)D levels were measured at baseline and after vitamin D replacement, and 25(OH)D pharmacokinetic parameters were determined, fitting the 25(OH)D concentrations to an exponential model.

    Mean measured increments in 25(OH)D at week 21 were 12.4 ± 9.7 ng/mL in the 1000 IU/d group, 27.8 ± 10.2 ng/mL in the 5000 IU/d group, and 48.1 ± 19.6 ng/mL in the 10,000 IU/d group. Steady-state increments computed from the model were 20.6 ± 17.1, 35.2 ± 14.6, and 51.3 ± 22.0 ng/mL, respectively. There were no hypercalcuria or hypercalcemia events during the study.

    Our data show that in obese people, the 25(OH)D response to vitamin D₃ is directly related to dose and body size with ∼2.5 IU/kg required for every unit increment in 25(OH)D (nanograms per milliliter).