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How Does The Body Produce Vitamin D From Sunlight?

Vitamin D, or “the sunshine vitamin,” helps regulate the amount of calcium and phosphate in our body. Together, those nutrients are needed for neuromuscular functions as well as our skeletal mineralization. In other words, vitamin D plays a significant role in keeping us strong and healthy. When someone is vitamin D deficient, it may cause rickets, a condition that affects bone development in children. Adults can experience a similar disease, which is known as osteomalacia or "soft bones" [1]. These complications affect almost 50% of the population worldwide. An estimated 1 billion people worldwide have a vitamin D deficiency (VDD) across all ethnicities and age groups [5]. One fact to remember is that vitamin D receptors are present in every tissue and cell of the human body.

Therefore, vitamin D deficiency has been linked to increased risk for several diseases such as preeclampsia or diabetes [3]. The good news is that you can prevent this from happening since the primary source of the vitamin is the sun [2]. Our skin naturally contains a precursor to vitamin D. When the sun's ultraviolet rays touch the skin, they convert the precursor to a molecule called vitamin D3.

After the absorption through the skin, vitamin D3 gets stored in the body's fat cells. When needed, the liver and kidneys turn the stored vitamin D3 into the active form the body needs (called calcitriol) [4]. Sun-induced vitamin D synthesis depends on the season, the time of day, latitude, altitude, air pollution, skin pigmentation, sunscreen use, passing through glass and plastic, and aging [2]. Our skin produces the vitamin D received from the sun, but the weather does not always allow us to have it from the sunlight. We should not forget that we can also obtain our daily vitamin D via foods and supplements.

Author: Carmen Havyarimana

Editor: Sophia Galvez & Anum Khan

Health Scientist: Beth Hanff



1. Dunkin, M. A. (2009, July 16). Vitamin D Deficiency. WebMD.

2. Matthias Wacker & Michael F. Holick (2013) Sunlight and Vitamin D, Dermato-Endocrinology, 5:1, 51-108, DOI: 10.4161/derm.24494

3. Michael F. Holick. (2011) Vitamin D: A D-lightful solution for health.

J Investig Med. 59(6): 872–880. doi: 10.231/JIM.0b013e318214ea2d

4. Moriarty, C. (2018, March 15). Vitamin D myths' d'-bunked. Yale Medicine. Retrieved November 19, 2021, from

5. Rathish Nair, Arun Maseeh. Vitamin D: The "sunshine" vitamin. J Pharmacol Pharmacother. 2012 Apr-Jun; 3(2): 118–126. doi: 10.4103/0976-500X.95506

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