Thursday, December 5, 2013

What Do Vit D, Vit K, and Liver Pâté Have In Common?

The skinny:
  • Vitamin D is an important vitamin-hormone important for bone mineralization, immune function, and serum calcium regulation
  • Vitamin D supplementation is less effective than simply embracing sunshine
  • research has shown that deficiency in Vitamin D may lead to a variety of diseases and that optimizing Vitamin D levels has numerous benefits
  • Vitamin K levels should be optimized concurrently with Vitamin D

Who you callin’ deficient, bozo?!

Winter is upon us.  For us northeasterners, this means a massive drop in temperature.  It’s enough to make a person want to stay inside for the next four months subsisting on canned corn and television.  If you’re familiar with Sweat and Butter’s philosophy on healthy living, this combo isn’t going to cut it.  You need exercise and nature to perform your best throughout the winter.  One of the primary concerns for northern Americans is Vitamin D deficiency.

The primary source of Vitamin D is the skin.  Vitamin D is distinct from other vitamins in that it behaves like a steroid hormone.  It begins in an inactive form called 7-dehydrocholesterol, which is quickly degraded by sunlight to cholecalciferol (D3).  D3 is converted to the prohormone calcidiol by the liver, then an enzyme found in the kidneys and most other tissues converts calcidiol to the active form of Vitamin D, calcitriol. (more here)  If you are confined to the indoors for most of your days, it’s highly likely that you’re deficient in Vitamin D, as the rate of D3 activation by the skin is key for maintaining Vitamin D levels in the blood.

(SIDE BAR: You might correctly assume from its name that 7-dehydrocholesterol is produced from cholesterol.  Logically, if you take statins, which are drugs that inhibit your liver’s capacity to produce cholesterol, you are even more likely to be deficient in the precursor for Vitamin D.)

Individuals with darker skin tone produce more melanin.  If you have lighter skin, melanocytes in your skin will produce melanin pigment upon exposure to sunlight, giving you the bronze tan for which you strive while on your beach vacation.  Melanin serves an important purpose, which is to absorb the energy carried by sunlight, minimizing the oxidative stress that leads to aging and certain types of skin cancer.  It makes sense that sun exposure prompts your skin cells to produce melanin as a means of protecting themselves from the sun!  The downside to having more melanin is that it competes with 7-dehydrocholesterol for the sun’s energy: the darker your skin, the less Vitamin D you produce.  This picture is further complicated by evidence that the production of melanin itself may actual predispose you to another type of skin cancer called melanoma.  The key is to find the right balance such that you expose your skin to moderate amounts of sunshine in order to maximize Vitamin D production while minimizing damage.
In addition to increasing your Vitamin D levels, getting outside also carries the benefit of improving your mood and productivity!

Production of Vitamin D from its inactive to active form

Roles of Vitamin D

Vitamin D serves three main purposes in the body: maintain calcium levels in the blood, direct bone mineralization, support immune function, and protect the skin.  As long as you aren’t deficient, these processes should continue as normal.  Vitamin D deficiency, on the other hand, has been linked by numerous studies to several important disease processes, including breast cancer, cardiovascular disease, diabetes, multiplesclerosis, and cognitive dysfunction.  

The "links" between low Vitamin D and the diseases mentioned above are merely correlative.  Correlations don’t prove causation in and of themselves.  Often the media present findings like these as "consuming more Vitamin D will prevent breast cancer, heart disease, MS and diabetes".  This is incorrect.  Studies such as these merely report a link between low Vitamin D and disease, but this doesn't mean that low Vitamin D causes these conditions.  However, we can drift closer to showing causation if we observe the incidence of disease when Vitamin D is added to the diet.  

Supplementing with Vitamin D has been shown to reduce multiple sclerosis symptoms and reduce the risk of fracture when supplemented in combination with calcium, but the other studies have been less than convincing.  For example, an often-cited study out of the University of Michigan is regularly used to show causation between Vitamin D supplementation and improvement of overall cardiovascular mortality.  Although this study showed a benefit from Vitamin D supplementation, it looked at its effects in mice, not humans.  On the other hand, optimizing vitamin K has been shown to improve cardiovascular disease risk.  A few other studies have shown that Vitamin D supplementation benefits immune function, particularly in protection against influenza.

Nevertheless, despite these studies being perfect, this is the way in which hypotheses become accepted fact.  Furthermore, it’s logical to assume that, if the body produces Vitamin D in response to UV light exposure on the skin, perhaps Vitamin D offers some protective benefit to skin cells.  I have observed this in my own experimentation with Vitamin D supplementation, but a study with one subject (n = me) isn't sufficient to draw any conclusions.  Vitamin D supplementation may decrease your risk of developing various diseases, but more evidence is needed to say for sure.  

Even though current evidence isn't sufficient, it's likely that upcoming studies will reveal additional benefits.  For now, I'm comfortable with recommending that you ensure that your Vitamin D levels are optimal year round.  As long as you don't go nuts with supplementation, it is likely to do more good than harm.

How to Optimize Vitamin D levels

As I’ve mentioned, sun exposure is your best bet.  A few 15-minute sessions daily should do the trick.  Obviously this is more difficult in the winter, but it’s really not too hard to get enough exposure to maximize your skin’s production of this vitamin.  In sixty seconds, I came up with the following:
  • walk or bike to and from work/church/school/the gym.
  • invest in some cold weather gear and move your workouts outdoors once or twice per week
  • build a fire and read/study/chat/surf the web fireside 
  • on the warmer days, drive with your window and sunroof open
  • take a walk during your lunch break
  • chop wood
  • roll up your sleeves while waiting for the bus
A note about windows and sunscreen: Many people ask about sun exposure through windows.  UV light is comprised of light waves of two lengths: longer UVA waves and shorter UVB waves.  UVA waves are associated with oxidative stress, aging effects, and more dangerous skin cancers, such as melanoma as they penetrate more deeply.  UVB waves are responsible for sun burns, Vitamin D production, and less dangerous skin cancers, such as squamous cell cancer.  Glass allows predominantly UVA waves to pass, meaning the sunshine on the left side of your face while driving to work is actually doing more harm than good.  More importantly, it's not influencing your Vitamin D levels because only UVB stimulate the production of Vitamin D.  Because Vitamin D has a protective effect on UVA light exposure, increasing the ratio of UVA to UVB is a double whammy since there isn't a proportional amount of Vitamin D around to counter the effects of the UVA.  Similar logic can be applied to sunscreen.  If you are hanging out at the beach for a half hour, you are getting both types of waves.  Research into the impact of sunscreen on exposure to UVA versus UVB waves is insufficient, in my opinion, but the evidence so far suggests that sunscreen use doesn’t affect Vitamin D production.  Having said that, check the label on your sunscreen to make sure that its active ingredients don’t preferentially block out only UVB.

Wait…what about tanning beds?  UVA rays penetrate more deeply, enabling them to hit the melanin-producing melanocytes.  UVB rays only hit the more superficial skin cells, causing sun burn.  The tanning industry thus harnesses predominantly UVA rays so that you walk out with the tan but without the burn.  Ain’t a good idea…

If you are still unable to optimize your Vitamin D levels through sunlight exposure, you might want to consider oral supplementation.  Living in Pittsburgh while working long hours in the hospital, I find it difficult to get outside as much as I would like.  I take a tablespoon of cod liver oil daily.  Interestingly, I haven’t burned in the sun since I began supplementing in June.  Being part Swedish, my boyish, pasty skin easily burns under normal circumstances, but optimizing my Vitamin D levels seemed to do the trick.

If you live in a part of the country that prompts people to say things like, “Oh, Pittsburgh!  I hear you have pretty crappy weather…” then you should probably consider supplementing orally with Vitamin D.  Based on my review of the literature, I recommend supplementing  with 3,000 to 5,000 IU of vitamin D3 in order to keep your serum levels hovering around 30 nanograms per milliliter.  Better yet, you could try a butter oil/cod liver oil blend, which contains both Vitamin K2 (butter) and Vitamin D (cod liver) to support the synergy between these Vitamins (keep reading for more on this synergy).

" finished my cod liver oil?!"
image: elshazam - deviantART


Because Vitamin D is fat-soluble, it will accumulate in your fat tissue when levels surpass the body’s ability to degrade it.  Storage of Vitamin D for later isn’t necessarily a bad thing, but too much can be toxic.  The upper threshold for this toxic limit is going to vary from person to person.  Because I just spent the beginning of this article describing in depth how most of our nation is Vitamin D deficient, toxicity from this vitamin isn’t something that the medical community has to deal with often.  It’s most likely to occur as the result of excess oral supplementation, so be careful.  I recommend having your Vitamin D levels checked before and a month after you begin supplementing to see just how well you respond to different dosages.

Vitamin D increases absorption of calcium from the gut as well as from the kidneys, and the majority of the symptoms reflecting toxic Vitamin D levels are secondary to hypercalcemia (e.g. muscle cramps, nausea, decreased appetite, fatigue, constipation).  These symptoms will often creep up unnoticed, but toxicity can lead to serious problems down the road such as impaired kidney function and the calcification of arteries. 

Vitamin Synergy

The negative consequences of over-supplementing with Vitamin D may be curbed by ensuring that your Vitamin K levels are optimized simultaneously.  Vitamin K comes in two forms K1 and K2.  K1 is found in leafy vegetables; K2 is found in grass-fed dairy products.  Vitamin D and Vitamin K2 work synergistically to maintain bone mineralization.  In fact, when Vitamin K2 is low, the effects of Vitamin D toxicity go through the roof.  On the other hand, Vitamin D depletes Vitamin K2 through an unknown mechanism, so these vitamins need to be maintained in careful balance.  The paucity of extensive literature supporting Vitamin D supplementation in the management of the aforementioned diseases may actually due to a relative depletion of Vitamin K2 in those studies!  The take home point is to supplement with Vitamin K2 concurrently if you're supplementing with Vitamin D.  

In their book, The Perfect Health Diet, the Jaminets recommend taking 100 micrograms daily of MK-7, a form of K2 produced by bacteria.  You should also do your best to eat Vitamin K rich foods such as grass-fed butter, fermented foods, aged cheese, liver, and leafy greens.

With a little help from the sun and wise food choices, you should have little difficulty optimizing your Vitamin D levels.  Over the long haul, your bones, immune system, brain, and arteries will thank you.  Don't let the lack of sunshine in your town get in the way of optimal health.  Take advantage of the sunshine when you get the opportunity; fall back on supplements when required.

Nathan Riley is a 2014 MD candidate at Temple University School of Medicine.  He writes about food, movement, sleep, relationships, and stress in order to bridge the gap between his patients and evolutionary theory and clinical evidence. You call follow him on Twitter @BeyondtheMD.  He can be reached at  You can also connect with him on Google+.

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