What is Vitamin D & Why is it Important? Vitamin D helps to regulate the amount of calcium and phosphate in the body, which are important for keeping our teeth, bones and muscles functioning in optimum condition. But more than this, this vitamin has actually been found to play a role in both arms of our immune system [1,4,10]. We have 2 arms? As a matter of fact we do.
The first arm, known as our innate immunity, controls our immediate reaction to a pathogen - a bacteria, virus or microorganism that can cause disease. This is our alarm system that tells our body that there is something present that shouldn’t be. The second arm, called adaptive immunity, is our memory of the immune system. This system is responsible for making antibodies, which help to identify infections that we may have been exposed to previously, and helps to coordinate how our body responds.
So what does this all mean? Essentially that Vitamin D plays a role in fighting infections and keeping us from getting sick. It has also been thought to even participate in the regulation against more serious autoimmune conditions like Multiple Sclerosis. [1,4,10]
Furthermore, emerging studies and research are supporting the possible role of vitamin D against cancer, type 1 and 2 diabetes, heart disease and depression [3,4,5,6,8]
So how do we get Vitamin D?
This is a unique vitamin in that it can be made in our skins with the help of exposure to sunlight, specifically UV B light . Adequate exposure to sunlight with bare arms, legs and hands will normally provide enough vitamin D for any given human; however, here lies a caveat or two.
Those with darker skin have a natural protection from the sun and will therefor require anywhere from three to five times the amount of sunlight exposure to make the same amount of vitamin D as someone with lighter skin [2,4]. Not to mention there remains much discussion over whether or not sunblock itself hinders the vitamins absorption [4,11]. There is also no set amount of time that determines how much sun exposure is actually required to produce sufficient Vitamin D levels. So it’s not ideal. But this is not to say that you shouldn’t get outside and enjoy the sun safely whenever you can.
Vitamin D can also come from food sources, which include oily fish such as salmon, sardines, herring and mackerel, red meat, liver and egg yolks.
Does this mean you have to start eating mackerel and liver for breakfast, lunch and dinner and sit outside for hours on end? Absolutely not, and please don’t.
Get yourself a once-daily supplement. It’s the easiest way to track how much vitamin D you’re getting and ensuring you are neither above nor below the daily recommendations.
So how much vitamin D should I take? Is there such a thing as too much vitamin D?
The National Institute of Medicine’s Dietary Allowance for Vitamin D is as follows: 
400 IU for infants/children 0-1 year old
600 IU for children, teenagers and adults 1-70 years old
Remember however, it is always best to consult your family doctor or local healthcare provider for what dosing is appropriate for you.
AND YES! YOU CAN OVERDOSE ON VITAMIN D
Vitamin D like Vitamins E, A, K (I call them the DEAK Vitamins) are fat-soluble vitamins. Bare with me here. What this means is that our body actually stores the excess vitamin levels that we don’t need rather than peeing it out like we do with all the other water-soluble vitamins, like B12 and C for example.
Overdosing on Vitamin D or Vitamin D toxicity while rare is called Hypervitaminosis D. It presents most commonly as confusion, fatigue, persistent vomiting, belly pain, increased and frequent urination and dehydration . It’s important to understand that this condition results from a long-term intake of high doses of vitamin D or from eating too much polar bear liver (an incredibly rich source of Vitamin D, too rich in fact). While it is treatable, it can be dangerous and is best to avoid altogether. This is why checking in with your health care provider whenever you start taking any supplement is important!
Because it is fat soluble, it is best to take your vitamin D supplement WITH food to improve its absorption.
So that’s all I have for you.
Get outside, wear your sunblock, take your vitamin D supplement, wash your hands and don’t waste any days!
Have questions? Email email@example.com and I’ll get back to you as soon as I can!
With love from your favorite doc,
- Azrielant, S., & Shoenfeld, Y. (2017). Vitamin D and the Immune System. The Israel Medical Association journal : IMAJ, 19(8), 510–511.
- Clemens, T., Henderson, S., Adams, J., & Holick, M. (1982). Increased Skin Pigment Reduces The Capacity Of Skin To Synthesise Vitamin D3. The Lancet, 319(8263), 74-76. doi:10.1016/s0140-6736(82)90214-8
- Cuomo, A., Giordano, N., Goracci, A., & Fagiolini, A. (2017). Depression and Vitamin D Deficiency: Causality, Assessment, and Clinical Practice Implications. Neuropsychiatry, 07(05). doi:10.4172/neuropsychiatry.1000255
- Hewison, M. (2011). Vitamin D and immune function: An overview. Proceedings of the Nutrition Society, 71(1), 50-61. doi:10.1017/s0029665111001650
- Kennel, K. A., & Drake, M. T. (2013). Vitamin D in the cancer patient. Current Opinion in Supportive and Palliative Care, 7(3), 272-277. doi:10.1097/spc.0b013e3283640f74
- Kheiri, B., Abdalla, A., Osman, M., Ahmed, S., Hassan, M., & Bachuwa, G. (2018). Vitamin D deficiency and risk of cardiovascular diseases: A narrative review. Clinical Hypertension, 24(1). doi:10.1186/s40885-018-0094-4
- Marcinowska-Suchowierska, E., Kupisz-Urbańska, M., Łukaszkiewicz, J., Płudowski, P., & Jones, G. (2020). Vitamin D Toxicity: A Clinical Perspective. Prime Archives in Endocrinology. doi:10.37247/paendo.1.2020.8
- Nair, R., & Maseeh, A. (2012). Vitamin D: The "sunshine" vitamin. Journal of pharmacology & pharmacotherapeutics, 3(2), 118–126. https://doi.org/10.4103/0976-500X.95506
- Nutrient Recommendations : Dietary Reference Intakes (DRI). (n.d.). Retrieved January 08, 2021, from https://ods.od.nih.gov/HealthInformation/Dietary_Reference_Intakes.aspx
- Saul, L., Mair, I., Ivens, A., Brown, P., Samuel, K., Campbell, J. D., . . . Mellanby, R. J. (2019). 1,25-Dihydroxyvitamin D3 Restrains CD4+ T Cell Priming Ability of CD11c+ Dendritic Cells by Upregulating Expression of CD31. Frontiers in Immunology, 10. doi:10.3389/fimmu.2019.00600
- Young, A., Narbutt, J., Harrison, G., Lawrence, K., Bell, M., O'connor, C., . . . Philipsen, P. (2019). Optimal sunscreen use, during a sun holiday with a very high ultraviolet index, allows vitamin D synthesis without sunburn. British Journal of Dermatology, 181(5), 1052-1062. doi:10.1111/bjd.17888