Vitamin D and Obese Adolescents

Dr. Fran Cogen Health Pro
  • I remain intrigued about Vitamin D and its relationship to diabetes, obesity, and overall health. As I have written in past blogs, there appears to be a correlation with sunlight exposure (and Vitamin D levels) with the development of Type 1 diabetes. Countries furthest away from the equator appear to have higher incidences of type 1 diabetes. Once again, this information does not prove that low Vitamin D levels cause diabetes, however, there seems to be some relationship between metabolism and Vitamin D.


    In the paper, “Correcting Vitamin D insufficiency improves insulin sensitivity in obese adolescents: a randomized controlled trial” (The American Journal of Clinical Nutrition, doi: 10.3945/ajcn.112.050013), Belenchia, Tosh, Hillman, and Peterson once again discuss Vitamin D and its relationship to insulin. According to the authors, obese adolescents appear to be at greater risk of Vitamin D deficiency due to the hypothesis that Vitamin D is stored by excess fat tissue. As I stated above, the authors noted that low Vitamin D levels are associated with metabolic syndrome and type 2 diabetes in both adolescents and adults.

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    The goal of the study was to determine the “efficacy and safety of 4,000 IU Vitamin D3 and if subsequent increased circulating concentrations of 25-hydroxyvitamin D (common lab measurement for Vitamin D levels) are associated with improved markers of insulin sensitivity and resistance and reduced inflammation.”


    Who were the subjects?

    1. 35 obese adolescents with an average age of 14 with a BMI of 39.8 and a 25-hydroxyvitamin D level of 19.6+/-7.1 ng/mL were recruited from The University of Missouri’s Adolescent Diabetes and Obesity Clinic.
    2. The 35 adolescents were randomly assigned to receive Vitamin D3 at 4,000 IU/dose OR placebo.
    3. Measurements of various metabolic components including inflammatory markers, fasting blood sugars, and anthropometric features were obtained at baseline and at 3-month and 6-month follow-up visits.


    What were the results?

    1. After 6 months, there were no significant differences in BMI, serum inflammatory markers, or plasma glucose levels between groups.
    2. Subjects supplemented with Vitamin D3 as compared to those with placebo had:
      1. Increases of 25 hydroxyvitamin D levels of 19.5 ng/mL and 2.8 ng/mL respectively (p<0.001).
      2. Fasting insulin levels (-6.5 uU/mL and +1.2 uU/mL respectively (p=0.026).
      3. Inflammatory markers remained unchanged.



    The authors conclude that correction of poor Vitamin D status through dietary supplementation of Vitamin D may help in the treatment of obesity and associated insulin resistance. According to Dr. Peterson, “by increasing Vitamin D intake alone, we got a response that was nearly as powerful as what has been seen using a prescription drug.”


    What is the practical implication of this paper?

    I have been checking hydroxyvitamin D levels in many of my patients due to my interest in the association of Vitamin D and diabetes. In many cases, I have found them to be low, especially in my obese patients with type 1 and type 2 diabetes. I have been supplementing with vitamin D3 in an effort to increase levels to greater than or equal to 30 ng/mL. Anecdotally, I have yet to note any significant changes in insulin sensitivity in terms of insulin doses. I will continue to supplement in view of the lack of harm to patients and the unknown benefit that might result from the Vitamin D administration.

Published On: April 17, 2013