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Vitamin D Simplified

Vitamin D, the sunlight vitamin. How do we get it, what does it do, and what happens if we get too much or too little?

Nutrition For the Curious Public

vitamin d

By Stefanie Schwartz MS, RD, CDN, Richard Strongwater MD, and Stuart M Caplen MD


Cholecalciferol (Vitamin D3) is produced in the body when ultraviolet rays from the sun hit the skin and trigger vitamin D synthesis from cholesterol.


Vitamin D is actually a group of fat-soluble vitamins but only two, vitamin D2 also called ergocalciferol, and vitamin D3 also known as cholecalciferol are present in humans. Vitamin D4 is present in certain mushrooms and the benefits of it in humans is uncertain.


forms of vitamin D - D2, d3, d4, Calcitriol

Sources of Vitamin D

Cholecalciferol (Vitamin D3) is produced in the body when ultraviolet rays from the sun hit the skin and trigger vitamin-D synthesis from cholesterol. The liver then converts vitamin D3 to calcidiol, and then the kidneys convert calcidiol to the active form, calcitriol.


In food, Vitamin D2 is generally ...

Read the full article for more about Vitamin D:


Risk Factors for Vitamin D Deficiency

Why Vitamin D?

Vitamin D Deficiency Defined

Too Much Vitamin D ?

Current Recommendations


Read the full Vitamin D Simplified article on www.FibonacciMD.app


 

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References

  • LeFevre, M and LeFevre, N. Vitamin D screening and supplementation in community-dwelling adults: Common questions and answers. American Family Physician. 2018;97:254-260.

  • Institute of Medicine, Food and Nutrition Board: Dietary Reference Intake for calcium and D. Washington DC: National Academy Press. 2010.

  • Davis CD. Vitamin D and cancer: current dilemmas and future research needs. Am J Clin Nutr. 2008;88:565S-569S.

  • Stolzenberg-Solomon RZ, Vieth R, Azad A, et al. A prospective nested case-controlled study of vitamin D status and pancreatic cancer risk in male smokers. Cancer Res. 2006;66:10213-10219.

  • Jones G. Pharmacokinetics of vitamin D toxicity. Am J Clin Nutr. 2008;88:582S-586S.

  • Horlick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011;96:1911-1930. Retrieved from: https://doi.org/10.1210/jc.2011-0385

  • Ensrud KE, Ewing SK, Friedman L, et al. Circulating 25-hydroxyvitamin D levels and frailty status in older women. J Clin Endocrinol Metab. 2010;95:5266-5273.

  • Dror AA et al. Pre-infection 25-hydroxyvitamin D3 levels and association with severity of COVID-19 illness. PLOS One. February 3, 2022. Retrieved from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0263069

  • Martineau AR et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data BMJ 2017; 356 :i6583. Retrieved from: https://www.bmj.com/content/356/bmj.i6583

  • Holick MF. High prevalence of vitamin D inadequacy and implications for health. Mayo Clin Proc. 2006 Mar;81(3):353-73. Retrieved from: https://pubmed.ncbi.nlm.nih.gov/16529140/

  • Vitamin D Fact Sheet for Health Professionals. National Institutes of Health. Updated: August 17, 2021. Retrieved from: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/

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