Vitamin D Toxicity

Are concerns about vitamin D toxicity valid?  This article examines this issue and provides you with information you may need to know....

dTo put this issue in perspective the comments of a doctor who has specialized in studying this vitamin may be of interest: Dr. John Cannell concluded:

"worrying about vitamin D toxicity is like dying of thirst in the desert while worrying about drowning."  from [The Truth About Vitamin D Toxicity]

The Symptoms Of Vitamin D Overdose

In fact, there are several symptoms which may be early signs of a vitamin D overdose, or simply a side effect for people who are intolerant to supplements. Those that have been identified are:

  • Bone pain
  • Constipation (especially in children or adolescents)
  • Diarrhea *
  • Drowsiness *
  • Dryness of mouth
  • Headache (continuing) *
  • Increased thirst *
  • Increase in frequency of urination, especially at night, or in amount of urine
  • Irregular heartbeat
  • Itching skin
  • Loss of appetite
  • Metallic taste
  • Muscle pain
  • Nausea or vomiting (especially in children or adolescents) *
  • Unusual tiredness or weakness *
[* Noted by Dr. Bruce Eichelberger, OMD]

If you experience these symptoms together and/or repeatedly they may result from vitamin D toxicity.  The prudent thing to do would be to suspend using Vitamin D or calcium supplements, stay out of sunlight and consult your doctor and tell him that you have been taking Vitamin D and how much.

The Upper Limit of Vitamin D Tolerance

Government agencies have established what they call the 'Tolerable Upper Limit' (TUL) dosage for vitamin d supplements, (It may also be named 'safe upper limit'). This is in their view the maximum amount which healthy people can use for long periods of time without experiencing any undesirable effects.

As of February, 2011 the US Office of Dietary Supplements states the Vitamin D TUL for all people over 9 years old is 4000 IU (100mcg) daily, however, there is no unanimous agreement that this is valid.  Many experts have amassed a large amount of research about  However there has been research into Vitamin D which leads these specialists to argue that this maximum limit should actually be the Recommended Daily Allowance (RDA) instead.

An article called "The Pharmacology of Vitamin D, Including Fortification Strategies" reports that

" ... despite 70 years of experience with the use of super-physiological amounts of vitamin D, there has never been a report of a sudden excess of vitamin D ...", that "Toxicity in normal adults requires intake of more than 1000 mcg/day (40,000 IU/day), which reflects amounts of vitamin D that are four times more than the 250 mcg/day can be acquired naturally by sunshine" and, perhaps most importantly that "If a consumer wanted to achieve [a] toxic dose, he or she would need to take forty of the 1000 unit pills (the highest dose available in North America without a prescription) every day for many months".

In another study reported in the American Journal of Clinical Nutrition, reported that review by that journal using the same methods which the Food and Nutrition Board uses to assess risk concluted:

"that the UL (safe upper limit) for vitamin D consumption by adults should be 10,000 IU per day" and this implies that adults could  comsum more than 10 times the amount which was currently recommended without any risk.

-Vieth et al, 'The urgent need to recommend an intake of vitamin D that is effective'

There is a further study of pregnant women were given 100,000 International Units (IUs) per day (ten times the TUL) for their entire pregnancy and this lead to the conclustion that  "... there is no evidence in humans that even a 100,000 IU/d dose of vitamin D for extended periods during pregnancy results in any harmful effects."

Sunshine Risks

Since we manufacture our own vitamin D from sunshine it is important to note that there have been no reports of Vitamin D toxicity from too much sunshine.

The body automatically prevents too much Vitamin D from being made through the skin.  As the skin gets darker through tanning, vitamin D production stops. Of course there are other reasons to limit your exposure to the sun, but getting too much vitamin D is not one.

If there is any likelyhood of overdosing is is most likely to come from overusing supplements far in excess of recommended limits.

Tips and Advice

  • People who work at nights, who are continually indoors, or wear clothing which limits skin exposure to sun are likely to need a supplement to get sufficient vitamin D.
  • Users of anticonvulsive drugs may need a supplement of vitamin D.

  • Dark skinned people living in far northern or southern latitudes may need supplements of vitamin D.

  • To get best use of Vitamin D vitamins A and C, together with choline, calcium and phosphorus are recommended.

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