Tuesday, June 22, 2010

Sunshine of Your Love Part 5: Toxicity

 Image courtesy of wikipedia
In fact, living in America today while worrying about vitamin D toxicity is like dying of thirst in the desert while worrying about drowning. --Dr. Cannell, The Vitamin D Council

Read The Whole Series:

What about toxicity?

Have you heard the stories?  They are pretty scary.  Bones dissolve, people pass painful kidney stones, kidneys fail, soft tissues turn to bone--fun stuff!

This fear is why the National Institutes of Health recommends "adequate intake" levels of only 600 IU (from food AND supplement) daily, which "represents a daily intake that is sufficient to maintain bone health and normal calcium metabolism in healthy people."  Their recommended blood level of 25(OH)D of only 15 ng/mL is "generally considered adequate for bone and overall health in healthy individuals."  Their established "tolerable upper intake level" is 2,000 IU (which is LESS than a bunch of us take each day in supplement!) saying "long-term intakes above the UL increase the risk of adverse health effects." However, short-term high dosages of up to 50,000 IU per week for eight weeks are considered safe.  In short, they are VERY concerned about toxicity.

Compare those conservative recommendations with the Vitamin D Council's for 5,000 IU daily for two to three months (if sunlight exposure is inadequate) before testing 25(OH)D levels to achieve a 50-80 ng/mL level year-round.  And the Vitamin D Council is not as concerned about toxicity--hence, the above quote.

What should we believe?  Is the government's conservatism warranted?  Well, in their favor: there isn't much evidence that high dosages (greater than 10,000 IU daily) are safe for prolonged periods of time, so you probably don't want to exceed that number by supplementation.  However, if you get some sun, you likely WILL exceed that number since your skin can make the equivalent to ingesting 10,000 IU in less than an hour (I know, I know, it all depends on age, skin color, latitude, time of day, etc.--but you get the picture).  Another however: your skin has a turn off valve once it reaches enough vitamin D (about 20,000 IU): the UV starts to degrade the vitamin D, never allowing overproduction.  Neat huh?

Unfortunately, we don't have the same turn off value internally when we ingest vitamin D, so there is a potential risk of toxicity.  BUT there is another however: there isn't much evidence that levels up 10,000 IU daily are harmful.  There is little to no basis for that 2,000 IU upper limit.  This literature review from 1999 in the American Journal of Clinical Nutrition concludes that there is very little data on moderate dose toxicity and NO data on 10k IU dosage being toxic.  Okay, so that is ten years old.  Let's look more recently.   

How about 2009?  This journal article published in the Annals of Epidemiology reports that prolonged 10k IU dosage is safe, up to a blood level of 25(OH)D of 88 ng/mL.

More specifically, the "lowest observed adverse effect level" (the upper, upper limit) currently set at 4,000 IU by medical standards is safe to use long-term, according to Vieth, author of the 1999 review and coauthor of this commentary in the Canadian Medical Association Journal from 2002.  Hypercalcemia (see next section), the symptom of toxicity, has only been shown to rear its bony head at blood concentrations of 25(OH)D in excess of 150 ng/mL, so the current upper limit of 100 ng/mL is safe, as concluded by a 2008 article in the American Journal of Clinical Nutrition.  

This gives us a few options:
  1. If you don't get adequate sun daily, you might want to think about supplementing, but keep it below 10,000 IU a day.  This is great for the winter too.  Best bet: Get Tested!
  2. If you do get some good sun, reduce your supplementation on those days or the days following exposure (vitamin D sticks around up to three weeks in your body). 
  3. If you regularly get some sun, but not enough, supplement on the conservative side and get tested to figure out how to reach your goals.  
  4. If you really think you get enough sun to meet your needs, get tested to confirm that.  Remember, it is highly unlikely even in the sunshine state!
What is hypercalcemia?

Hypercalcemia, or elevated calcium levels, is the first sign of too much vitamin D.  If you remember from our last installment, some recommendations were to test calcium along with vitamin D since the two go hand in hand (vitamin D regulates calcium levels).  There are other cofactors involved with vitamin D levels too, but calcium seems to be a runaway train once vitamin D levels get too high.  Since calcium is involved in bone growth and repair, too much spells overgrowth of bone and calcification of soft tissues (yeah, just like it sounds: they harden like bone).  Primal Wisdom's Don Matesz shares a personal experience of one of his patients with a salivary stone that went away once he reduced the patient's vitamin D supplementation and treated her with Eastern Medicine (herbs and acupuncture).

So how do you know you are skirting toxic waters with vitamin D supplementation?  There is a cute pneumonic for symptoms of hypercalcemia:
  • moans (nausea, vomiting, anorexia, weight loss, constipation, abdominal pain, etc.) 
  • stones (ex. kidney stones) 
  • groans (sometimes called psychic groans for memory problems, confusion, fatigue, weakness, etc.)
  • bones (bone pain, arthritis, osteoporosis, etc.)  
For more about hypercalcemia, read this article from the American Academy of Family Physicians.

How likely is toxicity?

The Vitamin D Council downplays toxicity concerns citing lack of evidence for high dosage health concerns beyond some questionable research, plant-based D2 toxicity (which is not the same as animal-based D3), and an overdose on mislabeled high dosage pills.  They point the finger at vitamin D hypersensitivity usually due to underlying conditions like hyperparathyroidism (the primary cause of hypercalcemia), some cancers, sarcoidosis, granulomatous tuberculosis, kidney disorders, and lymphoma.  If you have any of these conditions, DO NOT supplement your vitamin D without medical supervision.

Since the sun supplies us with 10,000 IU of vitamin D after a half hour of optimal exposure, it seems to follow that we can safely take up to that amount by supplement.  Heavy supplementation coupled with sun exposure could run the risk of toxicity, but according to the Vitamin D Council, this has never been reported yet.  

This article from the Weston A. Price Foundation does some good de-bunking even of their own contributing author's conservative recommendation not to exceed 800 IU of vitamin D a day from all sources without testing and medical supervision.  Their official recommendation (1-2,000 IU a day for 40-50 ng/mL levels) ends up a little less conservative than hers, but still more conservative than that of the Vitamin D Council.  More than any set-in-stone numbers to live by, they recommend you eat whole foods to keep your vitamins A, D, and K in balance.  Vitamin D toxicity is merely a relative deficiency in vitamins A and K.  We'll delve deeper into the Weston A. Price Foundation recommendations when we discuss cod liver oil in a future installment.  Stay tuned!

Primal Wisdom adds an interesting warning specific to those off the grains.  Author Don Matesz cautions those on a gluten-free diet that vitamin D might be better absorbed without gluten mucking up the process, so calcification is a potential problem for some, like his patient with the salivary stone.  There is also a connection with magnesium (surveys have shown that most Americans are only meeting half of the RDA for magnesium, while paleo dieters might be meeting their needs).  Low magnesium intake spells bone breakdown and reduces levels of activated vitamin D.  Matesz concludes:
This would mean that people who do not get adequate magnesium would show signs of vitamin D deficiency despite adequate sun exposure or vitamin D intake.  Conversely, people who consume more magnesium-rich foods, such as my paleo-dieting patient, require less vitamin D, and may more easily suffer from vitamin D excess. 
Thus, he more conservatively recommends for paleo dieters 25(OH)D levels of 40-60 ng/mL instead of 50+ as advised by the Vitamin D Council.  Magnesium is definitely a topic for another day!  

As the Weston A. Price Foundation and Primal Wisdom show, there are also some important cofactor interactions here with vitamins A, K, and minerals like zinc, magnesium, calcium, and phosphorus, so do your homework to make your OWN choices.  For more about cofactors, check out this page from the Vitamin D Council.  Most of the websites I reference in this article have tackled the cofactor issue since vitamin D does NOT exist in a vacuum and has many other interactions that are worth taking into account and researching.  But that, my friends, is a topic for another day :)

As is multitasking your fish oil and vitamin D needs through cod liver oil.
Keep reading here:

This is NOT medical advice to take vitamin D or any other supplements.  Consult your doctor (and try to educate him/her with this information), do some research, and formulate your OWN plan.

References in addition to those cited above:
Wikipedia entries on Vitamin D and hypercalcemia


  1. Kristy, Impressive work, thanks. Don't know if you've kept up with the thought process I've worked out on my blog, but it's best summed up in the post Dr. Mike Eades made lately. Bottom line, in the various trade offs in risks we make, I would rather have the moderate sun, almost no sunscreen, and thus less melanoma risk, as opposed to the sun nazi approach with its attendant risks.

  2. Thanks for the comment, Paul! I read through your series on the latest from Dr. Eades and Mark's Daily Apple and have come to a similar conclusion. I think the sun is inherently nourishing, not harmful, but our diet (too high omega-6 content, intolerances, allergies, toxins, and the rest of the mess) exacerbates the problems it causes. It's sad that we can't all get the sun we need to meet our vitamin D needs, but when we can't, at least there are careful supplementation strategies to help.