programs gym photos nutrition videos

The Vitamin D Primer


A Primer on D (by Coach Jacob)

Impress your friends.

Tell them you need to spend time outdoors “in order to acquire your daily dose of calcitriol”.

Or just say you’re going outside to get some Vitamin D.



Deficient D

Various maladies are associated with vitamin D deficiency. In children, they can present with impaired growth, low levels of calcium, and rickets.1

As one grows older, a shortage of vitamin D can lead to an increased risk of cardiovascular disease as it increases the risk of “obesity, diabetes mellitus, dyslipidaemia, endothelial dysfunction and hypertension.”2

The most trustworthy collaboration of scientific authorities admit that while the evidence is contradictory, there are studies suggesting vitamin D has potential to reduce the incidence of certain kinds of cancers.3

We are still in need of good research to make the following conclusion, but there are human studies that demonstrate a relationship between low levels of vitamin D and insulin resistance4, which is a hallmark of diabetes, polycystic ovarian syndrome (PCOS), metabolic syndrome, and more.

Low vitamin D has been implicated as a factor in autoimmune diseases.5

As you can see, avoiding low D should be a high P (priority).


D in Context

Vitamin D doesn’t fit the traditional definition of a vitamin because people who wear Vibrams and don’t wear shirts in the summer get plenty of it from the sun.

That is, vitamins are basically necessary substances which we can’t synthesize ourselves. But this doesn’t mean you can go without vitamin D.


The only thing you can really go without is sunscreen.

If you need to protect yourself from EXCESSIVE sun exposure after you have gotten your daily dose, wear clothes or do like the rest of the animal kingdom does and find some shade.

If you do this regularly, your body will naturally adapt and crown you with… you guessed it! A tan!

Your body’s preemptive way of balancing the sun shine it needs with the damaging effects of the sun’s radiation.

Burning is a sign you’re doing it wrong, tanning is a sign you’re doing it right. If you don’t tan and just burn, then get your 15 minutes of sun and then cover-up.

15 Minutes?

Aging, melanin pigmentation, season, daytime, cloud cover, altitude, latitude, clothing, and sunscreen use are the key players that will affect the amount of sunlight that will do you good or do you harm.6

It is natural for vitamin D levels to fluctuate from low normal in the winter to normal or high normal in the summer.

Levels can change by as much as 25 nmol/L.

For example, in Ohmaha, the winter baseline levels of 25OHD (vitamin D) were 68 nmol/L and shimmied up to 86 in the summer, while in Toronto levels went from 35 nmol/L in the winter to 50 nmol/L in the summer.

This is normal.

One’s response to sunlight is also genetically dependent, thus there is individual variability.

In terms of pigmentation, the darkest person may need twice the amount of sunlight as the lightest in order to obtain the same safe and healthy UV dose!

Keep that in mind.

Know your roots.

Follow the New England Journal of Medicine’s advice:


Sensible sun exposure can provide an adequate amount of vitamin D3, which is stored in body fat and released during the winter, when vitamin D3 cannot be produced. Exposure of arms and legs for 5 to 30 minutes (depending on time of day, season, latitude, and skin pigmentation) between the hours of 10 a.m. and 3 p.m. twice a week is often adequate. Exposure to one minimal erythemal dose while wearing only a bathing suit is equivalent to ingestion of approximately 20,000 IU of vitamin D2. The skin has a great capacity to make vitamin D3, even in the elderly, to reduce the risk of fracture. Most tanning beds emit 2 to 6% ultraviolet B radiation and are a recommended source of vitamin D3 when used in moderation. Tanners had robust levels of 25-hydroxyvitamin D […] at the end of the winter and higher bone density as compared with nontanners (with levels of approximately 18 ng per milliliter […]. For patients with fat malabsorption, exposure to a tanning bed for 30 to 50% of the time recommended for tanning (with sunscreen on the face) is an excellent means of treating and preventing vitamin D deficiency. This reduces the risk of skin cancers associated with ultraviolet B radiation.


For those interested in just some of what vitamin D does in the body, let’s talk biochemistry.



Vitamin D assists in calcium absorption.

It can double your body’s ability to uptake calcium!8 It also enhances phosphorous absorption by up to 20% Both of these are the major components of teeth and bones.

Calcium’s role in the body extends far beyond contributing to the rigidity and integrity of the aforementioned structures, but also enables your muscles to work.

Vitamin D works it’s a lot of its magic by “inducing”, a fancy word for interacting with and causing something to happen, proteins in your small intestine called calbindin (in = enzyme, bind, cal = calcium…enzymes that bind calcium).  

These proteins essentially ferry calcium from our gut to our blood.

The Bottom Line

Regular sun exposure is paramount for optimal health and is only contraindicated in the most extreme of cases.

The amount required depends on a litany of factors, but the range required is somewhere between 10 minutes and an hour a couple times a week.

Getting this amount will ensure appropriate levels of Vitamin D more times than not. Healthy levels of vitamin D will reduce your risks of adverse health outcomes.

The health benefits acquired from sun exposure far outweigh the risks of damage with the deciding factor of which one will predominate being your closely monitoring your skin for burning and responding accordingly.

The answer isn’t “no sun”.

The answer isn’t “wear sunscreen”.

The answer is sufficient sun and logical protection thereafter.

You will have healthy D levels to show for it.



  1. Ladhani S, Srinivasan L, Buchanan C, Allgrove J. Presentation of vitamin D deficiency. Arch Dis Child. 2004;89(8):781-784. doi:10.1136/adc.2003.031385.
  2. Muscogiuri G, Annweiler C, Duval G, et al. Vitamin D and cardiovascular disease: From atherosclerosis to myocardial infarction and stroke. Int J Cardiol. 2017;230:577-584. doi:10.1016/j.ijcard.2016.12.053.
  3. Vitamin D supplementation for prevention of cancer in adults | Cochrane. /CD007469/ENDOC_vitamin-d-supplementation-for-prevention-of-cancer-in-adults_. Accessed January 31, 2017.
  4. Al-Shoumer KA, Al-Essa TM. Is there a relationship between vitamin D with insulin resistance and diabetes mellitus? World J Diabetes. 2015;6(8):1057-1064. doi:10.4239/wjd.v6.i8.1057.
  5. Agmon-Levin N, Theodor E, Segal RM, Shoenfeld Y. Vitamin D in systemic and organ-specific autoimmune diseases. Clin Rev Allergy Immunol. 2013;45(2):256-266. doi:10.1007/s12016-012-8342-y.
  6. Ross C, Taylor C, Yaktine A, Del Valle H. Dietary Reference Intakes for Calcium and Vitamin D. 2011.
  7. Holick MF. Vitamin D Deficiency. N Engl J Med. 2007;357(3):266-281. doi:10.1056/NEJMra070553.
  8. Shaker JL, Deftos L. Calcium and Phosphate Homeostasis. In: De Groot LJ, Chrousos G, Dungan K, et al., eds. Endotext. South Dartmouth (MA):, Inc.; 2000. Accessed February 2, 2017.


Related Articles:
What's The Deal With Sleep? 
Depression, Frustration, Determination
Pyramid of Fitness