Vitamin D: Not Just the Sunshine Vitamin Anymore

Vitamin D: Not Just the Sunshine Vitamin Anymore

The ever-so-popular “Sunshine Vitamin” (vitamin D) has been known for many years to be the bone vitamin that people sometimes lack when they don’t get enough of the sun’s UV rays. Various foods are fortified with vitamin D, doctors and nutritionists recommend vitamin D, and TV and other advertisements shout at us to take our vitamin D if we want healthy teeth, bones, hair, etc. But is that all vitamin D is good for? Or, are there any other benefits to taking vitamin D? And, what is all the hype about vitamin D3 in particular?

What is Vitamin D?

Regarding the two D vitamins (D2 and D3), vitamin D3 is the kissing cousin to vitamin D2. The only difference is that vitamin D2 (ergocalciferol) is synthesized in plants from a certain sterol, while vitamin D3 is synthesized in “us” by rays of UV light hitting a sterol found in our skin called 7-dehydrocholesterol. When this happens, this precursor sterol gets slightly rearranged to form vitamin D3 (cholecalciferol). Once formed, this sterol vitamin can do some pretty amazing biological actions within us to give us strong bones, a strong immune system, a healthy brain, etc. All in all, vitamin D has not been given quite the credit where credit is certainly due. In this article, we will focus primarily on vitamin D3.

How Does Vitamin D Work?

Vitamin D (whether D2 or D3) needs to get converted into its biologically active form 1,25-dihydroxycholecalciferol before it can do what it does. This happens in our kidneys and then gets shipped out to the rest of our tissues where it does its magic. Since all forms of vitamin D are fat-soluble, it requires transport proteins, or chaperones, to transport it from one part of the body to another. There are vitamin D receptors all over our bodies that have different affinities to different forms of vitamin D. Think of receptors as being the “doorbells” to individual cells. When the doorbell is rung by vitamin D (in this case 1,25- dihydroxycholecalciferol), a series of physiological actions take place to allow D to do what it does best. In most cases, it allows our DNA to transcribe some interesting proteins, many of which help calcium (and sometimes other minerals) to be absorbed more efficiently in our intestinal tract. So, we can almost think of vitamin D as acting like a “hormone”, in which it can almost be called one.

What Are Some of the Benefits of Vitamin D3?

Although vitamin D3 has been mainly used over the years for reducing the risk of osteoporosis, bone fractures1 and seems to increase bone density2, it also has demonstrated to be useful for a number of other conditions. For example, a reduction in certain cancers has been observed by patients being treated with D33, it has shown promise as a possible treatment for autoimmune diseases4, a reduction in the symptoms of menstrual pain5 has also been observed, as well as a few other conditions. There have been many cases in fact, that show the biologically active form of vitamin D being able to not only increase insulin production but improve its sensitivity6, this is why vitamin D may be a promising candidate for those of us who suffer from certain forms of diabetes. So, as we can see, cholecalciferol seems to be more than just the bonafide bone-builder that everyone is familiar with.

Vitamin D3 and Brain Health

Interestingly, hypovitaminosis D (low circulating serum levels of vitamin D) has been linked with poor cognitive function, particularly in older adults. When studies were done using vitamin D3 supplementation it was found that verbal memory, verbal fluency, and speed of processing were greatly impacted7 simply by taking vitamin D3. During the past few decades, vitamin D has seemed to appear on the scene as a serious candidate in nervous system development and function, and has been a therapeutic tool in a number of neurological pathologies. In fact, experimental observations support multiple mechanisms by which vitamin D can act against neurodegenerative processes8. Kind of makes us see the sunshine vitamin in a different light.

Vitamin D3 Deficiency

It’s been shown that hypovitaminosis D is very common in those of us who suffer from sickle cell anemia and can be effectively corrected with high doses of oral cholecalciferol9. Deficiencies have also been linked to bone loss and secondary hyperparathyroidism10. Infectious diseases, cardiovascular diseases, and hypertension have also been reported in cases of vitamin D3 deficiencies11. So, as we can see, supplementation with vitamin D3 can be extremely beneficial, especially with those who do not or cannot get the recommended amount of sunlight each day to prevent some of these conditions.

We now see many of the wonderful characteristics of vitamin D that perhaps were unknown to us before. From the way it works in our bodies, the different forms this vitamin takes, all the way to the many biological actions it performs, it’s no wonder why we can say vitamin D is no longer just the “sunshine vitamin” anymore. 


1. Bischoff-Ferrari HA, Willett WC, Orav EJ, Oray EJ, Lips P, Meunier PJ, Lyons RA, Flicker L, Wark J, Jackson RD, Cauley JA, Meyer HE, Pfeifer M, Sanders KM, Stähelin HB, Theiler R, Dawson-Hughes B (July 2012). "A pooled analysis of vitamin D dose requirements for fracture prevention". The New England Journal of Medicine. 367 (1): 40–9.

2. Cranney A, Horsley T, O'Donnell S, Weiler H, Puil L, Ooi D, Atkinson S, Ward L, Moher D, Hanley D, Fang M, Yazdi F, Garritty C, Sampson M, Barrowman N, Tsertsvadze A, Mamaladze V (August 2007). "Effectiveness and safety of vitamin D in relation to bone health". Evidence Report/Technology Assessment (158): 1–235.

3. Bjelakovic G, Gluud LL, Nikolova D, Whitfield K, Wetterslev J, Simonetti RG, Bjelakovic M, Gluud C (January 2014). "Vitamin D supplementation for prevention of mortality in adults". The Cochrane Database of Systematic Reviews. 1 (1).

4. Prietl B, Treiber G, Mader JK, Hoeller E, Wolf M, Pilz S, Graninger WB, ObermayerPietsch BM, Pieber TR., High-dose cholecalciferol supplementation significantly increases peripheral CD4⁺ Tregs in healthy adults without negatively affecting the frequency of other immune cells. Eur J Nutr. 2014 Apr;53(3):751-9.

5. Kucukceran H, et al., The impact of circulating 25-hydroxyvitamin and oral cholecalciferol treatment on menstrual pain in dysmenorrheic patients. Gynecol Endocrinol. 2018 Jul 25:1-5. 6

6. Schwalfenberg G. Vitamin D and diabetes: improvement of glycemic control with vitamin D3 repletion. Can Fam Physician. 2008;54(6):864-6.

7. Maddock J, Geoffroy MC, Power C, Hyppönen E., 25-Hydroxyvitamin D and cognitive performance in mid-life. Br J Nutr. 2014 Mar 14;111(5):904-14.

8. Landel V, et al., Vitamin D, Cognition and Alzheimer's Disease: The Therapeutic Benefit is in the D-Tails. J Alzheimers Dis. 2016 May 11;53(2):419-44

9. Wykes C, Arasaretnam A, O'Driscoll S, Farnham L, Moniz C, Rees DC., Vitamin D deficiency and its correction in children with sickle cell anaemia. Ann Hematol. 2014 Dec;93(12):2051-6.

10. Kurt A. Kennel, MD, Matthew T. Drake, MD, PhD, and Daniel L. Hurley, MD, Vitamin D Deficiency in Adults: When to Test and How to Treat. Mayo Clin Proc. 2010 Aug; 85(8): 752–758.

11. Reichrath J., Skin cancer prevention and UV-protection: how to avoid vitamin D deficiency? Br J Dermatol. 2009 Nov;161 Suppl 3:54-60.

Chad Brey, a California State University, Northridge alumnus, has since worked as a chemist for various analytical and research facilities such as Amgen, Baxter, and Nusil Technology. Since 1997 he has worked in the dietary supplement industry for companies such as Earthwise Nutrition (formerly known as Great Earth Vitamins) and has earned a number of certificates as an IACET-certified dietary supplement specialist. Chad has written dozens of technical articles on the specifics of how certain dietary supplements work. Chad has formulated and developed small and large molecules in research and development laboratories since 2003 and continues to consult others in R&D today.
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