Kotz D. Time in the Sun: How Much Is Needed for Vitamin D? Available at: https://health.usnews.com/health-news/family-health/heart/articles/2008/06/23/time-in-the-sun-how-much-is-needed-for-vitamin-d. Accessed May 16, 2018.
What is vitamin D? Vitamin D Council. Available at: https://www.vitamindcouncil.org/about-vitamin-d/what-is-vitamin-d. Accessed April 30, 2018.
Ginde AA et al. Demographic differences and trends of vitamin D insufficiency in the US population, 1988-2004. Arch Intern Med.2009;169(6):626-632.
Naeem Z. Vitamin D deficiency—an ignored epidemic. Int J Health Sci (Qassim). 2010;4(1):V–VI.
Vitamin D (Calcitriol). Vivo Pathophysiology. Available at: http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/otherendo/vitamind.html. Accessed May 2, 2018.
Drezner M. Patient education: Vitamin D deficiency (Beyond the Basics). Wolters Kluwer. Available at: https://www.uptodate.com/contents/vitamin-d-deficiency-beyond-the-basics/print. Accessed May 16, 2018.
How do I get the vitamin D my body needs? Available at: https://www.vitamindcouncil.org/about-vitamin-d/how-do-i-get-the-vitamin-d-my-body-needs. Accessed May 16, 2018.
Holick MF et al. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2011;96(7):1911-1930.
Lehmann U et al.Bioavailability of vitamin D(2) and D(3) in healthy volunteers, a randomized placebo-controlled trial. J Clin Endocrinol Metab. 2013;98(11):4339-4345.
Tripkovic L et al. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic reveiw and meta-analysis. Am J Clin Nutr. 2012;95(6):1357-1364.
Logan VF et al.Long-term vitamin D3 supplementation is more effective than vitamin D2 in maintaining serum 25-hydroxyvitamin D status over the winter months. Br J Nutr. 2013;109(6):1082-1088
